Exam 6: Cylinder Heads and Valve Train Mechanisms

Technician A says that whether combustion gases are leaking into the engine can be detected by measuring whether fuel hydrocarbons are present in the coolant. Technician B says that excessive gas pressure in the cooling system can indicate a head gasket leak. Who is correct?

Solid, short pushrods enable the use of higher injection pressures and reduced:

Care must be taken to inspect bolts for damage before reuse because all of the following, EXCEPT one, can lead to stress risers and breakage. Which one does not apply?

When adjusting the valve clearances on the engine, technician A says the valves are closed when the valve lifter or follower is on the inner base circle of the camshaft lobe. Technician B says that valves are always adjusted when closed while the lifter or follower is on the camshaft lobe outer base circle. Who is correct?

While discussing variable valve timing in diesel engines, technician A says that only dual overhead camshafts (DOHCs) use variable valve timing. Technician B says variable valve timing is not commonly used in diesel engines. Who is correct?

Very long periods of extended idle can lead to excessive formation of _____ on the back of the valve.

Technician A says that before reusing any head bolt, it should be inspected for nicks and pitting. Technician B says the service manual should be consulted before reusing because some bolts can only be used once. Who is correct?

Two technicians are discussing pushrod service. Technician A says that if the weld at the ball socket end fractures, oil can enter and accumulate inside the pushrod. Technician B says the easiest way to check for oil entering the pushrod is to listen to the sound made when dropped. Who is right?

What head design places the exhaust ports on the inboard side of the engine?

Which of the following reasons best explains why diesel engine cylinder heads use more head bolts per cylinder?

Technician A says to promote improved combustion at low speed and low engine loads, more turbulence is needed to better mix the intake air and fuel. Technician B says that the shape of the intake port is shaped so as to impart a twisting or spinning motion to the air as it enters the cylinder to increase turbulence. Who is right?

Traditional copper and brass used in head gaskets were replaced by metal and asbestos gaskets during the:

Technician A says that worn guides and missing valve stem seals lead to high oil consumption and blue smoke during acceleration. Technician B says that oil in the guides can carbonize, accelerating stem wear, and lead to more particulate emissions. Who is right?

Lighter weight designs now have greater durability and lower maintenance requirements while improving:

In dual overhead cam engines, one of the two camshafts may actuate an intake and an exhaust valve in each half of the cylinder. What is this type of camshaft called?

Valve overlap occurs during _____________.

During a valve adjustment, cylinder 6, the companion of cylinder 1, should have two tight rocker levers at TDC for number 1 cylinder because both the valves should be open as the engine moves through the _______ position.

Aluminum's primary advantage is its:

The condition where valves stay open, not returning to their seat, is known as:

Valve timing (opening and closing in relation to crank position) are controlled by the: