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Level 1 Automotive Engines
Automotive Engines Review, Level 1 Pre-Employment
498
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Undergraduate 1
01/16/2013

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Term
Bearing Clearance
Definition
The space between the bearing & the crankshaft that allows for expansion of parts while still allowing slipping.
Term
End Play
Definition
Measurable Aft or End free movement of an item. In the engine this would be in regards to the crankshaft.
Term
Long Block
Definition
An engine block assembly that includes the heads and valve assembly.
Term
Overhead Cam Engine (OHC)
Definition
An engine where the camshaft is located on the top of the head.
Term
Dual Overhead Cam Engine (DOHC)
Definition
Overhead Cam engine with one rail for intake and one rail for exhaust per head. On a V6, or V8 engine both rails would have 2 camshafts.
Term
Piston Slap
Definition
When a piston has too much clearance between the piston & the cylinder walls causing the piston to 'slap' against the cylinder.
Term
Poppet Valve
Definition
The type of valve used for the intake and exhaust valves on a four-stroke internal combustion engine.
Term
Pushrod Engine
Definition
An engine where the camshaft is located within the engine block and there are two valves per cylinder.
Term
Runners
Definition
Metal tubing of the intake & exhaust manifold that transfers air to the engine block cylinders and exhaust out of.
Term
Short Block
Definition
An engine block assembly that does not include the heads & valve train assembly.
Term
Standard Temperature and Pressure (STP)
Definition
25 degrees at sea level. What we use to measure air volume.
Term
How much is air volume affected by altitude?
Definition
3.5% with each 1000ft change.
Term
Stoichiometric
Definition
The ideal mixture of air to fuel in a 4-stroke engine. Equal to 15:1.
Term
Upper End
Definition
The upper part of the engine which includes the cylinder heads and valve train.
Term
Valve Train
Definition
Refers to the parts of the engine that are responsible for opening and closing the valves. Camshaft, lifters, pushrods, rocker arms, valves & springs.
Term
How many times does each valve open during 720 degrees of crankshaft rotation?
Definition
Once
Term
Which valve is usually NOT magnetic?
Definition
Exhaust
Term
What is another name for the Harmonic Balancer and what does it do?
Definition
Vibration Damper. Absorbs some of the vibrations in the crankshaft that could cause it to break.
Term
Name the 4 strokes of a 4-Stroke Engine.
Definition
Intake, Compression, Power, Exhaust
Term
Piston Stroke
Definition
The movement of a piston from TDC to BDC or vice versa. 180 degrees of Crankshaft rotation.
Term
What causes engine vacuum?
Definition
The movement of the pistons in the cylinder during the intake stroke.
Term
Atmospheric Pressure @ Sea Level
Definition
14.7 psi
Term
When does spark occur in the 4-stroke cycle?
Definition
Just before TDC on the compression stroke when compression causes the air/fuel to be very flammable.
Term
What causes the crankshaft to rotate in it's journals?
Definition
The movement of the piston during the power stroke.
Term
Which valve is larger, intake or exhaust, and why.
Definition
Intake. The exhaust valve is under high pressure and opens to relieve pressure in the cylinder, where the intake valve is under lower pressure and the air/fuel mixture takes up more room.
Term
What are the polished bearing surfaces of the crankshaft called?
Definition
Journals
Term
How do you tell what the main journals are on the crankshaft?
Definition
They are in line with the centre of the shaft.
Term
What attaches to the flange at the rear of the crankshaft?
Definition
The flexplate or flywheel.
Term
What is the name of the bearing that limits crankshaft end play?
Definition
Thrust Main bearing.
Term
What is the name of the front of the crankshaft that the crankshaft gear/sprocket and the damper or pulley is installed on?
Definition
Snout
Term
Name the 3 piston rings and their purposes.
Definition
The top 2 are compression rings and these are used to prevent blowby during the power stroke. The 3rd ring is the Oil Control Ring and it scrapes excess oil from the cylinder walls.
Term
What is another name for the piston pin and what do we call the area around the pin?
Definition
Wrist Pin, & the Piston Boss.
Term
What pushes the piston rings against the walls of the cylinder?
Definition
combustion pressure & to a lesser degree spring pressure
Term
What is piston ring end gap and what is it's purpose?
Definition
The space between the ends of the piston ring when installed on the cylinder. To allow for expansion during heat as well as create spring pressure.
Term
Bimetal Engines
Definition
An engine where two metals are used, usually aluminum and iron
Term
Companion Cylinders
Definition
or running mates will be cylinders that are both at TDC or BDC at the same time.
Term
Compression Ratio
Definition
Comparison of the volume of the cylinder and combustion chamber at TDC & BDC.
Term
Cross-Flow Head
Definition
A cylinder head where the intake & exhaust valves are across from eachother.
Term
Cylinder Bank
Definition
A row of Cylinders, ie. left and right bank in V-8
Term
Diesel-Cycle
Definition
a four-stroke cycle that uses compression ignition instead of spark ignition.
Term
Electrical Grid
Definition
The network of wiring, generating, and movement systems that transmit electricity.
Term
Electrolysis
Definition
Using electricity to break down water into hydrogen & oxygen.
Term
Firing Order
Definition
The order in which the cylinders ignite.
Term
I-head
Definition
cylinder head design where the valves are directly over the cylinder
Term
L-head
Definition
Cylinder head design where the valves are to the side of the cylinder. The head itself is flat.
Term
Oxides of Nitrogen (NOx)
Definition
Refers to all forms of Nitrogen Oxide that are created by the engine.
Term
Regenerative Breaking
Definition
a system used in hybrids that uses an electric motor/generator to slow down the vehicle and recharge the battery during braking.
Term
Stratified Charge
Definition
The spark is ignited in a smaller chamber which has a richer air-fuel mixture than the main cylinder. The flames from this charge are what ignite the main cylinder instead of the spark itself.
Term
Two-Stroke Engine
Definition
An engine that only has a compression and power stroke.
Term
Wankle Rotary Engine
Definition
An engine design without pistons or cylinders. Instead a triangular shaped rotor moves within an elongated engine cavity. Each side of the triangle is a different stroke in the cycle. No valves are needed.
Term
What are 3 ways cylinders can be arranged in block?
Definition
V, In-line, or Opposed
Term
What is the name of the area between the heads on a v-type block?
Definition
valleys
Term
In the following firing order what are the companion cylinders?
1-8-4-3-6-5-7-2
Definition
1-8-4-3
6-5-7-2
Term
What kind of engine has a combustion chamber that is flat?
Definition
Diesel Engine
Term
When referring to left and right banks of a V-style engine, which end are we looking from?
Definition
Flywheel
Term
Name the 3 spots that combustion can occur in terms of fuel 'points'.
Definition
flashpoint, firepoint, spontaneous combustion
Term
Which is more volatile, gasoline or diesel fuel?
Definition
gasoline
Term
Engine Displacement
Definition
An indicator of power output and fuel consumption of an engine.
∏ x radius squared x stroke length x # of cylinders
Term
Horse Power
Definition
Rate at which torque is produced. The measurement of work over time.
(Torque x RPM) / 5252
Term
Name the two types of cooling systems used in engines.
Definition
Air Cooling & Liquid Cooling
Term
What are the cavities in a liquid cooled engine called?
Definition
Water Jackets
Term
Name 9 Ways engines are classified
Definition
1. Displacement
2. Strokes per cycle
3. cylinder arrangement
4. # of cylinders
5. fuel type
6. cooling systems
7. valve arrangement
8. camshaft location
9. air induction
Term
Name the most common combustion chamber designs (3)
Definition
Hemi, Wedge, and Pent-Roof
Term
Which of the 3 combustion chamber designs is a 'non-turbulent' design?
Definition
Hemi
Term
What is the difference between a pent-roof combustion chamber and a hemi?
Definition
pent-roof has four-valves per cylinder where hemi has only two
Term
What are common gasoline engine compression ratios? Diesel?
Definition
gasoline: 8:1 - 10:1
diesel: 14:1 - 20:1 or higher
Term
BTU
Definition
British Thermal Units, measurement for heat.
Term
Crank Throw
Definition
One half of the total piston stroke
Term
Displacement
Definition
In an engine, cylinder displacement is the volume that the piston displaces in the cylinder as it moves from TDC to BDC
Term
Dynamometer
Definition
A device used to measure an engine's output
Term
Work
Definition
Measurement of Force x Distance.
Science Units: Joules (newton meters)
Engines: Foot-lb
Imperial Units: Watt
Term
Force
Definition
a push, pull, lift.
Science Units: Newtons
Engines: Lbs
Term
IMEP
Definition
Indicated Mean Effective Pressure
Term
Inertia
Definition
When moving needing to keep moving, or when at rest needing to stay at rest. (Newton's 1st law)
Term
Mechanical Efficiency
Definition
Refers to loss of friction in a vehicle, measured in Horsepower
Term
Momentum
Definition
product of a body's mass and speed
Term
Oversquare
Definition
Cylinder Bore that is larger than its stroke
Term
Power
Definition
how fast work is done
Term
Prony Brake
Definition
A type of simple dynamometer that uses friction.
Term
Pumping Loss
Definition
A measurement of the work needed to move air into and out of the engine.
Term
Road Horsepower
Definition
The horsepower available at the tires
Term
Swept Volume
Definition
A way to determine displacement.
∏r2 x stroke
Term
Thermal Efficiency
Definition
How effective an engine is at converting fuel heat energy into work.
Term
Undersquare
Definition
Cylinder Bore that is smaller than its stroke
Term
Approximately how much change in horsepower does each point of change in compression ratio result in?
Definition
4-6%
Term
What is a typical gasoline engine compression pressure?
Definition
125-175 psi
Term
Torque
Definition
turning or twisting force
Term
Volumetric Efficiency
Definition
The measurement comparing volume of airflow actually entering the engine with the maximum that theoretically could enter it.
Term
What is an average cylinder bore & engine stroke?
Definition
3.5 - 4"
Term
Displacement
Definition
The volume that the piston displaces in the cylinder as it moves from BDC to TDC.
Term
Effective Compression Ratio
Definition
The compression ratio taking into account when the intake valve closes in the compression stroke. Closing the valve later lowers the effective compression ratio.
Term
Gross Horsepower
Definition
the power available with only the water pump and alternator using power
Term
Net Horsepower
Definition
the maximum power available from the engine when all the accessories are turned on.
Term
Brake Horsepower
Definition
the usable horsepower at the crankshaft
Term
Scavenging
Definition
During high speed driving, the movement of the exhaust gasses leaving the cylinder creates a vacuum that assists with pulling the fuel/air mixture through the intake valve.
Term
Which has more heat energy, Diesel or Gasoline?
Definition
Diesel
Term
When is peak cylinder pressure reached.
Definition
10 - 20 degrees past TDC during the power stroke.
Term
Bearing Crush
Definition
Means the bearing extends up past the top of the parting line of the bore by .0005"-.0015". Crush promotes heat transfer & prevents bearing spin.
Term
Bearing Spread
Definition
The bearing face is slightly larger across the face than the housing. Keeps the bearing in place during assembly.
Term
Cam Ground Piston
Definition
Refers to the oval shape the piston skirt has when cold. It is oval across the piston boss as this is the area of greatest expansion when the piston heats up.
Term
Cylinder bore taper wear
Definition
when the piston rings wear out the top half of the cylinder bore where they ride.
Term
Lower End
Definition
the lower side of the engine assembly, includes crankshaft, piston, and piston rod.
Term
Torsional Vibration
Definition
Vibrations that occur from oscillating and twisting motion. The vibration damper is used to minimize these on the crankshaft.
Term
Name two wears cylinder bores wear.
Definition
Taper and out-of-round
Term
When a cylinder wall is damaged, what is the part that is installed to correct it?
Definition
Cylinder Sleeve
Term
Which way will the crankshaft rotate when viewed from the flywheel end?
Definition
counter clockwise
Term
Name 3 types of piston ring facings.
Definition
Chrome, Moly, Cast
Term
What part usually drives the oil pump driveshaft on a cam-in-block engine?
Definition
a gear on the camshaft/distributor
Term
Bare Head
Definition
a cylinder head with none of the rest of it's installed parts. Ie. valves, retainers & locks, seals, springs and rocker arms.
Term
Valve Guide
Definition
Integral or replaceable insert that guides the valve as it opens and closes.
Term
Ring Ridge
Definition
a ridge at the top of the cylinder caused by the movement up and down of the rings on the cylinder.
Term
Name the 2 types of replaceable cylinder sleeves.
Definition
Wet or Dry Sleeves
Term
Main Bearing Bores
Definition
Not interchangeable
Line Bored
Term
Crankshaft
Definition
converts the reciprocating up and down motion of the pistons into rotary motion. Located in the crankcase at the bottom of the engine.
Term
Main Bearing Journals
Definition
support the crankshaft in the crankcase
Term
Rod Journals
Definition
Crankpins, offset from the centerline of the crankshaft, the connecting rods attach to these. Have oil passages to supply pressurized oil to the connecting rods.
Term
What causes End Thrust on the crankshaft?
Definition
Pressure in the torque converter or the release spring pressure of the clutch.
Term
3 Important properties of a bearing
Definition
Embeddability
Conformability
Fatigue Strength
Term
Crankshaft Bearings are (two-piece, one-piece)
Definition
two-piece
Term
How are bearing inserts position in the bearing bore?
Definition
By locating lugs and oil grooves
Term
Standard bearing sizes
Definition
.010", .020", .030"
Term
Cam Bearings are (two-piece, one-piece) & are not needed on:
Definition
one-piece (seamed or full round)
OHC aluminum heads
Term
Unlike most of the engine components which are cast-iron or aluminum connecting rods are usually made of:
Definition
forged or cast steel
Term
The shape of the connecting rod is referred to as:
Definition
I-beam
Term
The piston pin will be offset to the:
Definition
Major Thrust Surface
Term
Major Thrust Surface
Definition
The side of the piston the receives the most pressure during the power stroke.
Term
Minor Thrust Surface
Definition
The side of the piston that receives the most pressure during the compression stroke.
Term
Piston Head Shapes
Definition
Flat Head, Cup Head, Hump Head, Dome Head
Term
Hypereutectic
Definition
A process that has Silicon added to Aluminum within a piston. This process allows them to be made lighter. They also expand less.
Term
Which expands more, cast iron or aluminum?
Definition
Aluminum (about twice as much)
Term
What are the two piston skirt styles?
Definition
Trunk and slipper skirt
Term
Which piston skirt type experiences more piston slap?
Definition
Slipper Skirt (short skirt = more slap)
Term
Compression Height
Definition
the distance from the center of the pin bore to the flat are at the top of the piston
Term
How are piston pins lubricated?
Definition
Splash lubrication
Term
The two types of piston pins to rod connection are?
Definition
pressed fit or full floating
full floating pins require bushings and c-clips or lock rings to keep them in place
Term
List 4 types of piston ring designs.
Definition
Plain, Taper Face, Barrel Face, Napier
Term
Moly Piston Rings
Definition
Cast Iron rings with a groove cut in the face where Molybdenum is inserted. These rings are very resistant to scuffing.
Term
Piston rings are made of:
Definition
Steel, or cast iron with a Moly or Chrome coating
Term
Ductile Iron Rings
Definition
stronger than regular iron and can withstand higher temperatures. Will not snap when twisted like regular cast iron rings.
Term
An engine that uses a single drop of oil with every power stroke would use
Definition
1 quart every 2 miles
Term
Balance Shafts
Definition
silent shafts, counterweighted balance shafts that are driven by the crankshaft in the opposite direction at twice the crankshaft speed.
Term
Name 3 types of oil pumps
Definition
External Gear, rotor or Gerotor, and internal gear (crescent) pumps.
Term
In terms of displacement, automotive oil pumps are:
Definition
Positive displacement pumps, the same amount of oil is pumped out with each rotation.
Term
An oil pump relieves excess pressure with the
Definition
pressure relief valve
Term
What controls the maximum oil pressure of the engine?
Definition
The tension of the relief valve spring
Term
List the function of the oil pump screen bypass valve.
Definition
To allow oil to flow into the engine in the event the filter becomes plugged, or during cold start conditions where the oil is too thick to flow easily.
Term
Too much bearing clearance can cause:
Definition
Low oil pressure at idle and knock.
Term
Satisfactory oil pressure at idle in an engine is:
Definition
25psi
Term
Crosshatch
Definition
a pattern in the piston cylinder that aids with lubrication
Term
Cylinder Glaze
Definition
when the pistons wear away the crosshatch pattern
Term
Line Honing or Line Boring
Definition
A process for aligning main bore. All main caps are installed and bored out at once.
Term
Lugging
Definition
A condition that occurs when the load on an engine is greater than the rpm's needed to properly pull the load.
Term
What type of threads do oil and heater fitting connections have?
Definition
Tapered pipe threads
Term
When a main bearing bore has changed colours what should a tech look for?
Definition
Cracks in the bore or a burned bearing bore
Term
Before measuring a block that is mounted by its end on a universal engine stand, what should be done?
Definition
place it on a flat even surface and install a torque plate
Term
What is typical piston-to-cylinder wall clearance?
Definition
0.001"-0.002"
Term
When the main bearing that is farthest from the oil pump shows excessive wear, what is indicated?
Definition
a dry start condition
Term
Dry Start
Definition
the engine is revved before oil has had a chance to reach the bearings
Term
What is the name of the plastic material that is used for measuring bearing clearance?
Definition
plastigauge
Term
Besides metal from worn bearings or a failed camshaft, what are two types of foreign material that can find their way into the oil pump?
Definition
nylon material from nylon timing sprockets, or deteriorated valve guide seals
Term
Clean oil galleries with a
Definition
Rifle Brush and hot soapy water
Term
After cleaning the block you should immediately
Definition
lubricate all machined areas to prevent rusting
Term
If an engine has been consuming coolant where should you check after cleaning the block?
Definition
look for cracks in the cylinder bores
Term
To prevent high pressure from blowing a core plug from it's hole.
Definition
Cross-stake the outside of the core holes after installation
Term
What is a good angle for crosshatching?
Definition
20-60 degrees
Term
0.25mm is equal to what in inches?
Definition
0.010"
Term
What do you do to a cylinder after it has been bored?
Definition
Hone it
Term
To check a crankshaft for cracks
Definition
Remove the sprocket and hang the crankshaft from a wire. Then lightly tap the crankshaft counterweights with a hammer.
Term
If a crankshaft is broken you should always check the.
Definition
Vibration Damper for damage
Term
A crank bearing that is showing much more wear than the others indicates.
Definition
A bent crank.
Term
The main cause of short bearing life is.
Definition
Dirt
Term
Excessive belt tension may cause excessive wear on the:
Definition
upper front main bearing
Term
Externally mounted oil pumps require
Definition
a gasket
Term
Bob Weights
Definition
Used when balancing a camshaft to simulate the weight of the pistons.
Term
Connecting Rod Resizing
Definition
Done when a rod bearing has burned or if the big end has stretched.
Term
Dynamic and Couple imbalance
Definition
two types of shaft imbalance that need to be corrected
Term
End Gap
Definition
the space between the ends of the piston rings, or between two things
Term
Force, Static, or Kinetic Imbalance
Definition
Vibrational imbalances in a shaft
Term
Four-Corner Scuffing
Definition
scuffing that occurs on both piston skirts next to the piston pin
Term
Primary Vibration
Definition
a vibration that occurs in the engine caused by piston motion
Term
Rocking couple
Definition
a type of vibration that causes an engine to rock end to end. Caused by cylinders that fire 180 degrees apart.
Term
Scuffing
Definition
when the piston and cylinder wall weld together at TDC temporarily. Every revolution of the piston will cause them to weld and break apart scuffing the cylinder wall.
Term
Stress Raiser
Definition
refers to the raising of stress on metal when it is damaged, weakening it.
Term
When the compression ring grooves are cleaned, what type of deposit is removed?
Definition
Carbon
Term
What causes scuffing?
Definition
Excessive heat
Term
In which oversizes are pistons & rings available?
Definition
0.020", 0.030", 0.040", 0.060"
Term
What minimum size should the ring end gap be per inch of cylinder bore?
Definition
.003-.004"
Term
If the bore size is increased by 0.010" how much does the ring gap increase by?
Definition
0.030"
Term
Where is the extra weight added when an engine is externally balanced?
Definition
Vibration Damper, or torque converter flex plate
Term
Backlash
Definition
the clearance between two parts, such as gears
Term
Base Circle
Definition
the main part of the cam without the lobe
Term
Duration
Definition
the number of degrees of crankshaft rotation that the valve is off of it's seat
Term
End Thrust Camshaft
Definition
results from the opposing force resisting the oil moving through the oil galleries. This causes the camshaft to push towards the rear of the engine.
Term
Whenever an engine is disassembled these are replaced.
Definition
Piston Rings
Term
Compression Rings are removed using a:
Definition
Ring Expander
Term
This part of the piston is the only part that can be cleaned on a wire wheel.
Definition
The top
Term
Pistons designed for use with low-tension rings have ______ ring grooves.
Definition
Shallower
Term
Which ring groove wears the most?
Definition
The top one
Term
Modern Aluminum pistons cause this to break instead of wear on the ring groove.
Definition
Piston Rings
Term
Normal ring groove clearance
Definition
0.002"-0.004"
Term
Replacement pistons weigh the same, less or more than the originals?
Definition
the same, they musn't offset the balance of the crankshaft by being heavier or lighter
Term
When piston ring wear is due to dirty air getting in.
Definition
The top ring will show more wear and vertical abrasive lines will be visible.
Term
Pressed fit piston pins are installed using ______ and removed with a ______.
Definition
Heat, Press
Term
Wear on opposite sides of the rod bearing indicates.
Definition
A bent piston rod.
Term
Crankshaft counterweights that are to heavy can be lightened by:
Definition
drilling to remove excess metal.
Term
To add weight to a piston.
Definition
It is added on the wrist pin.
Term
Where should you check first if a customer complains of engine vibration?
Definition
Check the engine mounts.
Term
Freewheeling Engine
Definition
an engine that is designed to ensure the valves and pistons do not collide if a timing chain breaks.
Term
Integral Valve Seat
Definition
A valve seat that is part of the head, only on Cast-iron heads.
Term
Interference Engine
Definition
an engine that is designed so that if a timing chain breaks the piston and valves will collide causing damage.
Term
Positive Stop
Definition
A rocker arm stud design that uses hydraulic lifters or lash adjusters and does not require valve adjustment.
Term
Valve lift
Definition
The distance a valve is opened
Term
Valve Overlap
Definition
The degree of crankshaft rotation where both the intake and the exhaust valves are open.
Term
Zero-Lash
Definition
Meaning there is no space between the lifter and cam lobe. Usually hydraulic lifters.
Term
What two materials are cylinder heads made of?
Definition
Aluminum and Cast Iron
Term
What are the two types of valve guides?
Definition
Integral and replaceable insert.
Term
If a car decelerating on a hill has exhaust smoke, what are two possible causes?
Definition
Leaking valve guides causing burning oil from bellmouth wear and the atomizer effect. Worn Piston Rings could also be a cause.
Term
The term for the reason that a vacuum can happen at the bottom of the exhaust valve guide.
Definition
Atomizer Effect
Term
What are 3 types of valve guide seals?
Definition
umbrella, positive, o-ring
Term
What is the name of the process that hardens integral valve seats?
Definition
Induction Hardened
Term
What can happen to a valve that has a margin that is too thin?
Definition
It can overheat and burn the valve
Term
Why would a spring have inner & outer coils?
Definition
two springs are used when stronger spring tension is required
Term
What are 3 things that the camshaft can drive besides opening the valves?
Definition
Distributor, oil pump, fuel pump
Term
What causes the camshaft to thrust towards the rear of the engine?
Definition
The opposing force from the oil trying to move through the galleries.
Term
An engine without a turbocharger or supercharger is called:
Definition
Naturally Aspirated
Term
What is the name of the type of lifter that must be held from turning?
Definition
Roller Lifter
Term
List 3 ways that a camshaft can be driven.
Definition
Gear, Belt, Chain
Term
The name for a part that is returned to replace a rebuilt or remachined part is:
Definition
a Core Replacement
Term
A leaking intake seal can cause:
Definition
Carbon buildup on the valve stem.
Term
Atomizer Effect
Definition
When the movement of the exhaust gases past the worn exhaust valve guide pulls oil into the exhaust.
Term
Which valve seal does most engines today utilize?
Definition
Positive seal
Term
Most valve seats are ground to:
Definition
45 degrees
Term
High quality valve seat inserts are made of:
Definition
Nickel or Cobalt (Stellite)
Term
Most Valve Faces are ground to:
Definition
45 degrees
Term
The intake valve is usually _________ than the exhaust valve.
Definition
35-40% larger
Term
What cools the Intake valve, the exhaust Valve?
Definition
cool air coming in from the intake, the valve seat
Term
A misfire that is evident at idle but not at higher engine speeds is caused by.
Definition
A burned valve.
Term
How do you tell if an exhaust valve is burned on an engine running at idle?
Definition
Put a piece of paper over the exhaust pipe, if it is leaking during an intake stroke the paper will be sucked against the pipe.
Term
What holds the valve and spring together?
Definition
valve locks or keepers
Term
What is a common rocker arm ratio?
Definition
1.4:1 to 1.75:1
Term
What controls the opening and closing of the valves?
Definition
The cam
Term
What determines the number of cam lobes on a cam shaft?
Definition
the number of valves needing to be opened
Term
Engines breathing ability
Definition
Volumetric Efficiency
Term
Why do opposed engines have half the cam lobes of a V or In-line?
Definition
the lobes of one cylinder are shared with it's companion cylinder
Term
The oil pump in some cam-in block engines is driven by the:
Definition
Bottom of the distributor
Term
What determines how well an engine breaths at a specific rpm?
Definition
the camshaft
Term
cam grind
Definition
the shape of the cam lobe
Term
Supercharged or Turbocharged engines are called:
Definition
Artificially Aspirated
Term
When a valve lift reaches this diameter of the port opening it is said to have no benefit if opened further.
Definition
25%
Term
This shape of the lifter, and this shape of the cam lobe worked together to cause a flat tapper lifter to spin.
Definition
Convex, Tapered
Term
Roller Camshaft is made from:
Definition
Steel
Term
Explain how a hydraulic lifter works
Definition
The body of the lifter is in constant contact with the cam lobe, as the lobe spins the body of the lifter begins to move up and the pushrod pushes against the lifters plunger. This movement will cause the check ball to seat and trap the fluid within the lifter. When this occurs the lifter moves as one and the valve begins to open.
Term
Two types of timing chain designs.
Definition
Silent and roller chain.
Term
Does a timing belt stretch like a timing chain?
Definition
No it does not
Term
When does the intake valve open?
Definition
Before TDC at the start of the intake stroke.
Term
When does the exhaust valve open?
Definition
Long before the end of the power stroke
Term
What gives high performance engines their distinctive "lope" sound at idle?
Definition
Valve overlap.
Term
Advanced cam timing:
Definition
Improves low and mid-range torque
Term
Retarded cam timing:
Definition
Improves high-rpm power
Term
VVT
Definition
Variable Valve Timing
Term
Active Fuel Management/Displacement on Demand
Definition
means of increasing fuel economy by disabling pistons
Term
Dye Penetrant
Definition
A way to detect cracks on a cylinder head, usually aluminum heads. Red Dye is applied then wiped off and a developer is sprayed to highlight the cracks.
Term
Interference Angle
Definition
Refers to the angle difference between the valve seat and valve face that is sometimes used to allow for newly reground seats and valves to wear to eachother. Usually a 1 degree difference.
Term
Knurling
Definition
a way to repair cast iron guides. The inside f the guide is made smaller than s reamed out to fit the valve stem.
Term
Mushroomed valve tip
Definition
the valve tip condition that results when there is too much valve clearance and the valve tip pounds against the lifter
Term
Pinning or Stitching
Definition
repairing cracks in iron heads using tapered, threaded plugs
Term
Thinwall
Definition
an insert used to repair valve guides
Term
Valve Clearance
Definition
Lash, refers to the space between the cam lobe and the cam follower.
Term
Valve Spring Installed Height
Definition
how much space the valve spring takes up when installed
Term
Valve Stem Height
Definition
a measurement that reflects how much a valve and valve seat have been ground
Term
After removing the valve spring, what measurement is made before removing the valve?
Definition
Valve stem height
Term
If 0.20" is removed from a cylinder head, approximately how much will valve timing change?
Definition
1 degree of retarded valve timing
Term
If a crack in a cast-iron cylinder head is to be repaired with tapered plugs, what is done to both ends of the crack?
Definition
They are drilled to prevent the cracks from spreading
Term
Three things hat a valve spring is checked for are:
Definition
tension, squareness and height
Term
To correct the installed spring height, a ______ is installed under a valve spring.
Definition
A Shim
Term
A ______ test can be done after a valve grind to ensure that the seats do not leak.
Definition
Solvent Test
Term
When these are to be reused on an engine with flat tappets, they must be kept in order.
Definition
Lifters
Term
When a cylinder head is removed to have the valves and seats refinished this is called.
Definition
A valve job
Term
When varnish buildup makes valve retainers stick to the valve locks.
Definition
strike each spring retainer with a brass hammer prior to using the spring compressor
Term
Aluminum heads always have this beneath the valve springs.
Definition
Steel Shim
Term
Before removing a mushroomed valve from the guide:
Definition
dress the tip with a file or whetstone
Term
OHC engines should not be cleaned with this type of blaster.
Definition
Bead blaster, the beads will get stuck in the oil galleries
Term
Heads should not be warped more than:
Definition
0.002" in any 6" length
Term
If the camshaft does no turn easily and the machine shop only resurfaces the bottom side of the head:
Definition
A broken camshaft can result
Term
Can warped aluminum heads be straightened?
Definition
Yes
Term
Magnaflux
Definition
a way to check for cracks in cast-iron cylinder heads
Term
What happens when water has been entering the combustion chamber from a leaking head gasket?
Definition
There will be no carbon on the surfaces of the combustion chaber
Term
Pressure testing of a Cylinder Head
Definition
Used to check for cracks. All openings are plugged and the head is filled with water or air. If air used soapy water is sprayed over the head or it is submerged in water to check for bubbles.
Term
When a valve seat has worn and is much larger than usual, look for:
Definition
a worn valve guide
Term
What is the seat width of intake and exhaust valves?
Definition
1/16"
3/32"
Term
What must be refinished before attempting to refinish valve seats?
Definition
Valve Guides
Term
Solvent Test
Definition
The head is set upside down in the solvent tank with the valves installed without springs. Solvent is put into the combustion chambers and leaks are watched for.
Term
Before installing seals be sure to:
Definition
Lubricate them
Term
With cam-in-block engines, as pushrods, rocker arms, and other valve train parts wear; Lash....
Definition
increases.
Term
As the valve and valve seat wear; Lash....
Definition
decreases
Term
If a flat-tappet cam is replaced, be sure to replace these as well as new ones will rapidly wear out a new cam.
Definition
Lifters
Term
Noisey Hydraulic lifters can be caused by
Definition
oil pressure issues, dirt lodged in the check valve causing wear
Term
Before installing a new timing belt on the sprockets or a new timing chain
Definition
position #1 piston at TDC and make sure the timing marks are lined up
Term
After a timing belt is installed you should do this and recheck the timing marks.
Definition
Rotate the crankshaft 2 revolutions
Term
Aerobic Sealer
Definition
a chemical sealer that needs air to cure (such as RTV)
Term
Anaerobic Sealer
Definition
a chemical sealer or liquid gasket that can cure without air
Term
Dynamic Seal
Definition
Generally made of butyl rubber or eveoprene, used to seal moving parts.
Term
Microinch
Definition
one millionth of an inch
Term
Non-retorque gasket
Definition
a modern gasket that compresses less than a conventional gasket so the head does not require retorquing
Term
Pre-load
Definition
refers to the clamping load on a fastener
Term
rubberized cork
Definition
a very common type of valve cover gasket material
Term
Torque-to-yield
Definition
when a bolt is torqued to within 2% of it's yield point.
Provides more consistent clamping force.
Developed for use on aluminum heads.
Term
Torque Turn
Definition
refers to a method used by manufacturers where a bolt is tightened then turned an extra 35-180 degrees with a torque angle gauge.
Term
Approximately how much of the torque applied to a fastener is used to overcome friction?
Definition
90%
Term
What is the metric torque equivalent of a foot-pound?
Definition
Newton-meter
Term
How much clamping load on a head gasket is used to seal combustion?
Definition
75%
Term
Does the lip of an oil seal face toward or away from the oil in the crankcase?
Definition
toward the oil
Term
When installing half of a rear main lip seal in a block, the parting line is positioned?
Definition
Offset with the parting line of the main cap
Term
What colour is the anaerobic locking adhesive used to assemble parts that are not intended to be disassembled again?
Definition
Red
Term
What does RTV stand for
Definition
Room Temperature Vulcanization
Term
RTV silicone sealant that is used with oxygen sensor systems.
Definition
Low-Volatile RTV that does not use acetic acid to cure
Term
Firewall
Definition
refers to the bulkhead part of the vehicle
Term
Ring Ridge
Definition
common in older engines, a ridge that forms at the top of the cylinder where the rings to do not travel
Term
Rod Bolt Protector
Definition
used to keep rod bolts from damaging the crankshaft journal on removal.
Term
What could cause a transmission bushing, wheel bearing, or emergency brake cable to burn or fail?
Definition
a missing or broken ground strap
Term
What is the name of the type of automotive refrigerant that depletes the earth's ozone layer?
Definition
R-12 or Freon
Term
Name two belt-driven accessories that can be wired out of the way without disconnecting their hoses.
Definition
Air Conditioning Compressor and Power Steering Pump
Term
Are engine mounts interchangeable?
Definition
No
Term
Engine stand mounting bolts should be at least ____ times the bolt diameter.
Definition
1.5
Term
What tool can be used to remove a vibration damper that will not need the crankshaft to be held from turning?
Definition
Impact Wrench, or a vibration damper pulley
Term
What are 3 types of torque wrenches?
Definition
Beam, Dial, Click
Term
A foot-lb torque wrench is not accurate below:
Definition
15 ft-lb
Term
A gasket set that contains everything needed for an engine rebuild.
Definition
A full set (FS) gasket set
Term
The type of head gasket that should not be used with gasket sealers.
Definition
Teflon-coated
Term
When too much metal has been removed from a head's surface, this can be used to compensate.
Definition
Shim
Term
What is the purpose of the small holes in a cylinder head gasket?
Definition
to control the flow of oil and coolant in the engine
Term
If the bolt holes of the oil pan are bent do this.
Definition
Straighten with a hammer
Term
The most common valve cover gasket materials:
Definition
rubberized cork, synthetic rubber, and silicone
Term
These two valve cover gaskets are used without sealers.
Definition
Silicone and Neoprene
Term
Gaskets that require a sealer.
Definition
Retorquable head gaskets and paper gaskets.
Term
These rules should be followed when reinstalling an exhaust manifold.
Definition
Steel side of the gasket faces toward the manifold.
Torque from inside to outside.
If one hole on the manifold is smaller than the others, this bolt goes in first.
Term
When an exhaust manifold bolt breaks what should be checked?
Definition
The exhaust valve in the port closest to the leak, it is most likely burned.
Term
3 functions of a gasket sealer
Definition
help gaskets seal
hold gaskets in place
substitute for a gasket
Term
RTV silicone should never be used to seal around this as it breaks down the silicone.
Definition
Fuel
Term
Too much silicone sealer can cause:
Definition
the oil pump pickup screen to be plugged when parts of it break up and fall into the oil
Term
Seals used at the front and rear of the crankshaft, or the front of an overhead camshaft.
Definition
Dynamic Seals, or Chevron Seals
Term
Two types of crankshaft rear seals
Definition
Neoprene lip seal and the Rope Seal
Term
What is the first thing that should be done when preparing to remove an engine?
Definition
Disconnect the battery
Term
PCM
Definition
Powertrain Control Module
Term
These connecting rods should NOT be marked using number stamps, or punches.
Definition
Powdered Metal Connecting Rods
Term
Do this before hot tanking a block
Definition
remove the core plugs
Term
Crank sprockets are positioned by this on the front of the crankshaft
Definition
woodruff or bar key
Term
Custom Engine Rebuild
Definition
a rebuild where the engine is to be used in the same vehicle it was removed from
Term
Engine kit
Definition
an engine part kit that contains all or most of the parts necessary to completely rebuild an engine
Term
Spin Test
Definition
a test done by engine rebuilders where the crankshaft is rotated @ 600rpm while lubrication system has full oil pressure
Term
Use this to clean bolt holes in the block before reassembly
Definition
A Tap
Term
Pry the crank forward and rearward before torqueing the thrust bearing cap to align the halves of this.
Definition
Thrust Main Bearing
Term
Check crankshaft end play with a:
Definition
dial indicator or feeler gauge
Term
Install these on rod bolts to protect the crank against accidental nicks during piston installation.
Definition
Rod bolt protectors or rubber hosing
Term
The crankshaft should be rotated how many times after installing each piston, and why.
Definition
1 turn, to make sure nothing is too tight
Term
When installing an OHC make sure the camshaft and piston are correctly ______ so they do not hit eachother.
Definition
Timed
Term
If the block does not have aligning pins what can be used to align the timing cover?
Definition
The vibration damper
Term
When installing a mechanical fuel pump, this item should be in the down or away position so that the pump arm is not activated.
Definition
eccentric
Term
Apply this before painting to areas where you don't want paint to stick.
Definition
Grease
Term
Tightening down an OHC camshaft sprocket with an impact wrench can result in a broken....
Definition
snout
Term
End Play Tolerance is usually ... to ... for a crankshaft with a 2" to 2 3/4" main bearing diameter.
Definition
0.004" to 0.006"
Term
Anti-Drainback Valve
Definition
a valve in horizontally mounted oil filters that prevents the oil from draining out of the filter when the engine is off.
Term
API
Definition
American Petroleum Institute, licenses & certifies Oils
Term
Boundary Lubrication
Definition
when the oil film becomes too thin & starts to break down under load
Term
By-pass oil filter
Definition
used in heavy duty applications. Only filter about 10% of oil at a time. Traps very fine particles.
Term
Crankcase
Definition
Area at the bottom of the engine enclosed by the oil pan
Term
Dry Start
Definition
When and engine is started when cold and it takes a few seconds for oil to reach the crankshaft. Or the engine is revved before the oil has time to reach the crankshaft.
Term
Full-Flow Oil Filter
Definition
used in todays passenger cars, All oil in the pump is supposed to flow through the filter.
Term
Multiple Viscosity
Definition
Engine oil that has two viscosity ratings.
One measured at 0F (cold) and one at 212F (hot)
Term
Polymer
Definition
included in oil additives, a polymer expands when heated allowing the oil to maintain viscosity
Term
Viscosity
Definition
the thickness of the oil and it's ability to flow
Term
Viscosity Index
Definition
the ability of oil to resist changes in viscosity when heated
Term
Under normal conditions when is the only time that oil film does not separate engine parts?
Definition
During Dry Start
Term
Give two possible problems that can result if the oil level in the crankcase is too high?
Definition
Oil can be thrown up into the bottom of the piston and overload the oil ring as well as cause aeration in the oil. Excessive exhaust flow & oil consumption.
Term
How is an engine dipstick different from a transmission dipstick?
Definition
The AT dipstick has direction on it & the add lines have different values (oil is 1 quart, AT is 1 pint)
Term
SAE
Definition
Society of Automotive Engineers
Term
What causes oil Oxidation?
Definition
Temps above 250F
Term
What is the name of the oil filter part that allows the oil to get to the engine bearings even if the filter is plugged?
Definition
By-pass valve
Term
If sludge forms in a modern engine, what additive is probably depleted?
Definition
Oil detergents and dispersants
Term
When figuring the amount of oil to add to the crankcase, add the amount specified plus some extra to compensate for what?
Definition
Filling of the oil filter
Term
Engine Oil
Definition
Lubricates, cleans, cools, and prevents rust
Term
ILSAC
Definition
International Lubricant Standardization and Approval Committee
Term
Oil Additives
Definition
Pour-Point depressants
Corrosion and rust inhibitors
Antifoam additives
Friction Modifiers
Oxidation inhibitors
Antiwear Additives
Term
Additives added to oil to keep small particle contaminants suspended in the oil.
Definition
Detergents and Dispersants
Term
Sludge
Definition
a mixture of moisture, oil and contaminants from combustion
Term
Excessive Oil temperatures can be caused by:
Definition
Lean air-fuel mixtures
Retarded ignition timing
using the air conditioner
an AT equipped vehicle pulling a trailer
Term
The ideal cooling temperature for oil is
Definition
195F
Term
Does Oil wear out?
Definition
no, just becomes contaminated and the additives deplete over time
Term
Bimetal coil spring:
Definition
a thermostatic coil in a fan clutch consisting of two metals wound together
Term
Cavitation
Definition
indents in the metal caused by bubbles in the coolant
Term
Cross-flow radiator
Definition
one of two types of radiators, this one is most used. Coolant flows horizontally.
Term
Detonation
Definition
self-ignition due to excessive pressure in the cylinder
Term
Down-Flow radiator
Definition
a radiator where coolant flows vertically
Term
Fan Clutch
Definition
Allows freewheeling of the fan @ cold temperatures & running at hot
Term
Heat exchanger
Definition
or transmission oil cooler, used to cool the tranny oil
Term
Heater core
Definition
a small heat exchanger in the passenger compartment that provides heat for the cabin
Term
Open loop
Definition
when a computer controlled engine is cold and not receiving feedback from the O2 sensor
Term
Preignition
Definition
when the air-fuel mixture ignites before the spark occurs
Term
Sending Unit
Definition
engine coolant temp sensor, sends the temp of the coolant to the computer/temp gauge
Term
Thermostat Bypass
Definition
a bypass passage that the coolant uses to keep circulating in the block when the temp is low
Term
Automotive coolant is made of ______ and water
Definition
Glycol, or ethelene glycol
Term
Cylinder blocks are made of
Definition
cast-iron or aluminum
Term
When electrical current develops between two dissimilar types of metal in the cooling system this is called:
Definition
Electrolysis, or chemical electrolysis
Term
Name of the coolant additive that protects aluminum:
Definition
Sodium Silicate
Term
What is the normal operating temperature of an engine?
Definition
180F - 212F
Term
For each pound of pressure on the coolant approximately how much will it's boiling point increase?
Definition
3 F
Term
What is the name of the small valve in the center of the radiator pressure cap?
Definition
Vacuum Valve
Term
This in the thermostat expands to cause it to open.
Definition
Wax compound
Term
What type of pump is the coolant pump
Definition
Centrifugal Impeller-type
Term
List the two types of glycol based coolant.
Definition
Ethelene Glycol, Propylene Glycol
Term
What has the best heat carrying capacity and why do we not use it in our engines for cooling.
Definition
Water, because it rusts components
Term
Why is the cooling system pressurized?
Definition
Pressurizing increases the boiling point of the coolant and increases the efficiency of the water pump.
Term
What do most rad caps pressurize the system by?
Definition
13 to 17 psi
Term
Before opening a radiator cap be sure to squeeze this. Why?
Definition
Top Rad hose, to make sure it collapses, if it does not then the system is still hot and it will boil if the rad cap is removed.
Term
Constant pressure caps have this to make sure the system can build pressure as the coolant starts to expand.
Definition
a spring-loaded vacuum valve
Term
What determines the maximum pressure of the cooling system?
Definition
The radiator cap
Term
What is the typical operating temperature of thermostats?
Definition
188 - 195 F
Term
Block Check Test
Definition
or combustion leak test is used to check for a leaking head gasket. Done with the engine running. Detects CO (exhaust) gas in the radiator.
Term
Coolant Hydrometer
Definition
a way to test coolant strength, compares the weight of the coolant to water
Term
Hydrolocked engine
Definition
when an internal leak fills a cylinder and the engine is turned off. If the cylinder is at BDC and the valves are closed the crankshaft will not be able to turn and will be Hydrolocked.
Term
Rodded out
Definition
a method of repairing copper/brass radiators
Term
Thermoplastic Seizure
Definition
when a leaking head gasket or cracked cylinder allows coolant into the crankcase. The oil/coolant mixture plugs oil rings and running seals. The sticky substance can prevent crankshaft turning.
Term
When the bottom of a radiator core feels considerably colder to the touch than it's top.
Definition
It may be plugged
Term
What type of radiator is usually replaced rather than repaired?
Definition
Aluminum
Term
When measuring the voltage of coolant what is the limit before the system needs to be flushed?
Definition
0.4V or higher
Term
What is the name of the test that compares the density of water and coolant?
Definition
Coolant density tester
Term
What removes rust and scale? What neutralizes this?
Definition
Acid, Base
Term
Alkaline is a
Definition
base
Term
Ethylene glycol coolant is dangerous to animals because it is
Definition
Poisonous
Term
Why is there a small home in some thermostats?
Definition
These are check valves to allow air to escape during filling as well as more accurate temperature control
Term
What is the name of the test that uses colored liquid to find exhaust gas in the cooling system?
Definition
Block Check Test
Term
If the water pump bearing or the fan clutch fails what sort of damage can result?
Definition
radiator damage
Term
If a heat exchanger leaks...
Definition
transmission fluid will go into the rad when the engine is running and coolant will flow into the transmission when the engine is off.
Term
Refractometer testing
Definition
measures coolant concentration and gives an indication of the freeze rating of the coolant in degrees
Term
Cooling system pressure test
Definition
performed with the engine off, can be done on a hot or cold engine, used to check for leaks. Pressurize the system to the pressure on the top of the rad cap. After 5 min the pressure on the gauge should be the same, if it has dropped there is a leak.
Term
Guide pins
Definition
used to align parts, similar to dowels
Term
Overhaul
Definition
an engine repair involving piston, piston ring and crank bearing replacement
Term
Pressure primer
Definition
a way to prime the lubrication system when removing the distributor is not possible.
Term
Steering linkage taper
Definition
a piece that connects the steering gear to the wheel.
Term
tempilstik
Definition
pencil shaped sticks that melt at different temperatures
Term
WOT
Definition
Wide Open Throttle, when the accelerator is to the floor and minimum vacuum is produced
Term
This tool can be used to drive the oil pump when priming the lubrication system.
Definition
A tool made from a distributor shaft with the gear removed
Term
During lubrication system priming, the tool is turned in this direction.
Definition
The same direction that the distributor operates.
Term
When a pushrod engine is first started, ever, it should be run at 1,500 - 2,000 rpm for....
Definition
20min
Term
The point where valve clearance is eliminated
Definition
Zero-lash
Term
When fuel boils in a fuel line
Definition
Vapor Lock
Term
If you need to replace a head gasket, what work is also probably necessary?
Definition
Head surfacing
Term
Which wood is less likely to break than standard lumber?
Definition
Plywood
Term
Black light
Definition
used with fluorescent liquid to check for leaks
Term
Cross-fluid contamination
Definition
when water leaks into the crank-case and mixes with the oil
Term
Engine knock
Definition
a knocking sound from the engine
Term
Flat Cam
Definition
refers to excessive wear on a cam lobe
Term
Oil Wash
Definition
when too much fuel is in the cylinder and it begins to wash away the oil
Term
Pressure relief valve
Definition
in the oil pump. This valve allows oil to return to the oil pan when too much pressure is output from the pump.
Term
Seized engine
Definition
when the starter motor does not crank the engine and the engine cannot be started by hand or turned over manually.
Term
Carbon has build up on the neck area of a valve, or a spark plug has a carbon deposit on only one side.
Definition
A valve guide is leaking
Term
What is one problem that can appear from Worn Rod Bearings, or High Speed Driving.
Definition
Oil Consumption
Term
A noise goes away when he spark for one cylinder is cancelled, what could the noise be?
Definition
A worn connecting rod or main bearing
Term
A noise becomes louder when one cylinder is cancelled, what could the noise be?
Definition
Piston Noise
Term
What is a common cause of a cracked piston?
Definition
Broken timing chain or incorrect timing causing the valves and piston to collide
Term
When a cylinder is worn excessively oval, what should be looked for?
Definition
Worn or collapsed piston skirts or excessive piston clearance
Term
When an engine is run for a long period with an excessively lean air-fuel mixture, what type of engine damage can result?
Definition
Burned internal parts and detonation
Term
When a piston has no carbon around the edges of the top what condition is suggested?
Definition
Excessive oil consumption past the rings
Term
When the top of a piston is clean of carbon what condition is suggested?
Definition
coolant is leaking into the cylinder
Term
When the top of a piston is covered in carbon deposits that are building up on the head, what condition is suggested?
Definition
Oil is leaking through the intake valve guide
Term
Engine Compression test
Definition
or leakage test, used to test compression of the cylinders.
Pressure gauge is installed in place of the spark plug, the ignition system is disabled and the throttle is blocked at WOT. Then the engine is cranked to let the cylinder go through 4 compression strokes.
Will help tell the condition of compression rings.
Term
Cylinders with low compression will cause
Definition
have a rough idle but the symptoms will disappear at higher rpm
Term
Wet Engine Compression Test
Definition
Used to pinpoint whether the compression rings are the cause of the low compression in a cylinder. A tablespoon of oil is squirted into a low cylinder. If the compression reading raises to near normal indicates a piston ring issue.
Term
Cranking Vacuum Test
Definition
Used to check for internal air leaks or incorrect valve timing.
Throttle plate is closed all the way and the ventilation system plugged. The PCV hose is blocked and ignition disabled. Then the engine is cranked, the needle on the gauge should stay steady.
Term
Causes a hissing sound from the tailpipe when under load.
Definition
A restricted exhaust
Term
Dry black suit in the exhaust pipe indicates
Definition
an overly rich air-fuel mixture
Term
Cylinder Leakage Test
Definition
Used to pinpoint combustion chamber leakage. Compressed air is introduced into the cylinder via the spark plughole and leaks are listened for in different places.
Oil Filler, Air Cleaner & Exhaust
Leakage test may also produce bubbles in the radiator or leakage in adjacent cylinders which indicate cracks or head gasket issues.
Term
Leakage Test Advantages over compression test
Definition
Can be done on an engine that is removed from a vehicle
A performance camshaft will not affect the results.
Term
Cylinder power balance test
Definition
RPM Drop test
Used to compare performance of cylinders
Computer control is in open loop and idle control is disabled. When disabling a spark to a cylinder it should cause an RPM drop. RPM drop between cylinders should be less than 5%.
Term
Smoke Testing
Definition
Used to locate vacuum, oil, cooling and exhaust leaks.
Vacuum - engine off and throttle closed
Exhaust - takes 2 minutes to fill the exhaust
Coolant and Oil - drain system, Pinch PCV hose
Term
An engine will not start. If there is a hot spark, the next tests are for:
Definition
fuel and compression
Term
A roar is heard through the intake manifold during testing
Definition
the exhaust system is restricted
Term
What appears on the outside of an exhaust pipe at the point of an internal restriction?
Definition
a discoloration
Term
Vacuum readings will drop approximately:
Definition
1" for each 1000 ft above sea level
Term
An engine should produce a minimum of ____ inches of vacuum while cranking but most will produce far more.
Definition
3
Term
When engine idle rises during a cylinder power balance test, what could be the cause?
Definition
a grounded out spark cylinder, EGR valve is open
Term
During a compression test remove all of these so the starter can crank easily.
Definition
Spark Plugs
Term
What is the minimum number of compression strokes an engine should crank during a compression test?
Definition
four
Term
Engine Mounts should be _____ _____ until all mounts are installed.
Definition
left loose
Term
Black soot on the exhaust pipe indicates:
Definition
an overly rich air-fuel mixture
Term
When there is oil on the engine side of the flywheel or torque converter what is indicated?
Definition
a rear main bearing seal leak
Term
Oil on the transmission side of the torque converter indicates
Definition
a front transmission seal leak
Term
This type of noise in reference to a fan can cause a noise that sounds serious and is hard to pinpoint.
Definition
fan clutch on the coolant pump
Term
Heavy knock after the engine warms up, most pronounced about 1500-2500rpm. Loosening an accessory belt often reduces the intensity of the knock.
Definition
Front Main Bearing Knock.
Term
Clunk when the vehicle leaves a stop sign, more noticeable if the vehicle has a manual transmission.
Definition
Thrust Bearing Knock
Term
When a spark plug is disabled during a cylinder balance test this knock will diminish or disappear, may be accompanied by low oil pressure at idle.
Definition
Rod Knock, from too much rod bearing clearance
Term
A deep knocking sound from the bottom of the engine.
Definition
A bent oil pan
Term
Ticking sound that resembles a valve train noise but comes from the crankcase.
Definition
Rod Side Clearance.
Term
Most common of engine noises
Definition
Valve train noises which make a loud ticking sound
Term
Popping noise through the air inlet
Definition
sticking intake valve
Term
Smooth idle, but runs rough under acceleration and a popping noise is heard.
Definition
Worn or flat Cam lobe
Term
Rattle or knock that becomes louder when decelerating.
Definition
Timing component issue
Term
Internal Leaks
Definition
Leaks enclosed within the engine
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