AUTOMOTIVE ENGINE DIAGNOSIS
AND REPAIR EXAM QUESTIONS AND
THEIR CORRECT ANSWERS
What does the top end of the engine consist of?
Cylinder head assembly
intake and exhaust manifolds
What does the bottom end of the engine consist of?
engine block
pistons and crankshaft
oil pump
What does the front end of the engine consist of?
valve timing belt
pulleys
water pump
What is the bore of the cylinder?
It's the diameter of the cylinder
What is the stroke of the cylinder?
It's the distance the piston travels from TDC to BDC
What is piston displacement?
The volume of gas moved by the piston from TDC to BDC
What is engine displacement?
# of pistons X # of cylinders
What is the formula for piston displacement?
Area of bore X the stroke
ex: (3.14)(Radius)^2 X Stroke
,How do you calculate compression ratio?
Total cylinder volume (measured at BDC) to the clearance
volume (measured at TDC)
ex:
Volume at BDC is 40 in, Volume at TDC is 5 in.
ratio is 40:5 or 8:1
Some main bearings have flanges to control forward
and reward force on the crankshaft. What are these
called?
these are called thrust bearings
Why do you need bearing clearence?
Because the crankshaft is supported by pressurized oil
and oil is pumped into the clearances between the journal
and bearing
What is a typical bearing clearance?
0.001"-0.003"
identify componets on the flip side of cue card
Are pistons perfectly circle?
No, they are move oval (cam ground).
The piston expands in cylinder as it heats up
What is the purpose for piston pin offset?
To reduce piston slap
What is the problem if you get a piston slap sound just
after an engine rebuild?
The piston may have been installed backwards, offset is
on incorrect side therefore causing piston slap
What are pistons rings made of?
Cast irons
chrome
moly
, What are the 3 rings for on a piston between the lands
for?
Top ring = Compression ring
Middle ring = 2nd compression ring that also scraps off
excess oil
Bottom ring = oil ring
What is a piston pin?
its a pin in the piston that holds the connecting rod
What are two types of piston pins?
Floating Pin
Press fit pin
Can you switch the connecting rod bearing caps
around when installing?
No because each bearing cap is unique to each other
cannot be switched around or used on another connecting
bearing
How are the connecting rod bearings lubricated?
Through the drilling passages in the crankshaft
What is the hottest part of the engine?
The cylinder heads because of the combustion and valves
getting hot
What operates the valves?
directly from camshaft
pushrods and rocker arms
How are valves closed?
With coil springs
how is the camshaft driven?
AND REPAIR EXAM QUESTIONS AND
THEIR CORRECT ANSWERS
What does the top end of the engine consist of?
Cylinder head assembly
intake and exhaust manifolds
What does the bottom end of the engine consist of?
engine block
pistons and crankshaft
oil pump
What does the front end of the engine consist of?
valve timing belt
pulleys
water pump
What is the bore of the cylinder?
It's the diameter of the cylinder
What is the stroke of the cylinder?
It's the distance the piston travels from TDC to BDC
What is piston displacement?
The volume of gas moved by the piston from TDC to BDC
What is engine displacement?
# of pistons X # of cylinders
What is the formula for piston displacement?
Area of bore X the stroke
ex: (3.14)(Radius)^2 X Stroke
,How do you calculate compression ratio?
Total cylinder volume (measured at BDC) to the clearance
volume (measured at TDC)
ex:
Volume at BDC is 40 in, Volume at TDC is 5 in.
ratio is 40:5 or 8:1
Some main bearings have flanges to control forward
and reward force on the crankshaft. What are these
called?
these are called thrust bearings
Why do you need bearing clearence?
Because the crankshaft is supported by pressurized oil
and oil is pumped into the clearances between the journal
and bearing
What is a typical bearing clearance?
0.001"-0.003"
identify componets on the flip side of cue card
Are pistons perfectly circle?
No, they are move oval (cam ground).
The piston expands in cylinder as it heats up
What is the purpose for piston pin offset?
To reduce piston slap
What is the problem if you get a piston slap sound just
after an engine rebuild?
The piston may have been installed backwards, offset is
on incorrect side therefore causing piston slap
What are pistons rings made of?
Cast irons
chrome
moly
, What are the 3 rings for on a piston between the lands
for?
Top ring = Compression ring
Middle ring = 2nd compression ring that also scraps off
excess oil
Bottom ring = oil ring
What is a piston pin?
its a pin in the piston that holds the connecting rod
What are two types of piston pins?
Floating Pin
Press fit pin
Can you switch the connecting rod bearing caps
around when installing?
No because each bearing cap is unique to each other
cannot be switched around or used on another connecting
bearing
How are the connecting rod bearings lubricated?
Through the drilling passages in the crankshaft
What is the hottest part of the engine?
The cylinder heads because of the combustion and valves
getting hot
What operates the valves?
directly from camshaft
pushrods and rocker arms
How are valves closed?
With coil springs
how is the camshaft driven?
