Sample Review Questions:
1. Which of the following must be removed to repair an intake manifold coolant or vacuum leak?
a. Cylinder head
b. Exhaust manifold
c. Intake manifold
d. Timing cover
2. Which of the following is NOT true about head gaskets?
a. Head gaskets can leak fuel
b. Head gaskets can leak coolant
c. Head gaskets can leak combustion pressure
d. Head gaskets can leak oil
3. Which of the following is NOT true about MLS head gaskets?
a. They must be retorqued 500 miles after being installed
b. They require very smooth and flat surfaces on the head and block to seal properly
c. They typically have 3 to 5 layers of steel
d. They are usually used with torque-to-yield (TTY) head bolts
4. If an engine has a leaky rear main oil seal, the oil would be leaking:
a.Near the harmonic balancer and crankshaft pulley
b. Near the flywheel
c. At the camshaft plugs
d. At the back of the valve covers
1C, 2A, 3A, 4B
The intake manifold gasket seals the intake manifold to the cylinder
head. On many V6 and V8 engines, it also seals the intake manifold to
the engine block. The gasket prevents air/vacuum leaks at the cylinder
head intake ports, and coolant leaks at the cylinder head coolant
ports. Coolant and vacuum leaks past the intake manifold gasket are
common in high mileage engines. To replace the gasket, the intake
manifold must be removed.
2. The head gasket seals the cylinder head
to the engine block. This prevents coolant from leaking into the
cylinders from the coolant jackets inside the block. The gasket also
seals the cylinders so combustion pressure cannot leak externally or
between cylinders. It also seals the oil passages between the block and
head. A poor seal in any of these areas, or damage to the gasket can
allow coolant, compression or oil leaks to occur. Head gaskets can be
damaged by engine overheating, internal corrosion from worn out
coolant, or improper installation (not torquing the bolts properly, not
cleaning both mating surfaces, not having smooth, flat clean mating
surfaces, or using a sealer on a coated gasket that does not require
3. Multi-layer steel (MLS) head gaskets are used on
many late model engines to improve durability. They usually have 3 to 5
layers of steel, and are coated with a thin layer of rubber. No sealer
is needed. To seal properly, MLS head gaskets require a very smooth,
flat surface on the head and block. TTY head bolts are used with MLS
head gaskets to assure even loading and to reduce cylinder distortion.
TTY head bolts should not be reused. MLS head gaskets do not require
re-torquing after the initial installation. Aftermarket MLS head
gaskets are available for some engines that were originally equipped
with ordinary head gaskets. An MLS gasket may be recommended to prevent
premature gasket failure in a “problem” application.
Lip-style oil seals are used a the front and rear of the crankshaft to
seal the engine. A worn rear main oil seal can allow oil leaks near the
flywheel at the back of the engine. A bad front oil seal can leak oil
near the crank pulley. Replacing a one-piece rear main oil seal
requires separating the engine and transmission, and removing the
Crankshaft oil seals must have a smooth, polished
surface on the crank. If the surface of the crank is rough or worn, it
can damage a new seal. A simple fix for this is to slip a repair sleeve
over the end of the crank when the new seal is installed.
oil plugs in an overhead cam (OHC) engine can leak oil at the back of
the cylinder head. Oil leaks on the sides of the engine are most often
due to old, cracked or damaged valve cover gaskets.
Engine Mechanical Parts
Suspension and Steering