ASE Practice Test (A1: Engine Repair) 2

Question 1

A technician is measuring piston ring end gap and finds it is less than the manufacturer's specification. What is the correct action?

Accepted Answer

File the ring ends carefully to achieve the correct gap

Answer

When piston ring end gap is too small, the ring ends can butt together during engine operation causing the ring to break or score the cylinder wall. The technician should use a ring file to carefully enlarge the gap to within specification.

Question 2

When pressure testing a cooling system, a technician finds the pressure drops slowly over 15 minutes with no visible external leaks. What is the most likely cause?

Accepted Answer

Internal head gasket leak

Answer

A slow pressure loss with no visible external leaks strongly indicates an internal leak, most commonly a blown head gasket allowing coolant to enter the combustion chamber or oil passages. External leaks would be visible on the ground or engine components.

Question 3

A diesel engine has excessive crankcase pressure (blow-by). Which component failure is MOST likely responsible?

Accepted Answer

Worn piston rings and cylinder walls

Answer

Excessive crankcase pressure (blow-by) occurs when combustion gases bypass the piston rings and enter the crankcase. Worn piston rings and cylinder walls allow this gas passage, increasing crankcase pressure significantly.

Question 4

During engine assembly, a technician checks main bearing clearance using Plastigage and finds it measures 0.001 inch. The specification is 0.0010–0.0025 inch. What should the technician do?

Accepted Answer

The clearance is acceptable; proceed with assembly

Answer

A clearance of 0.001 inch falls exactly at the minimum of the specification range of 0.0010–0.0025 inch, making it acceptable. The technician should proceed with assembly using proper torque and lubrication procedures.

Question 5

A technician is replacing valve stem seals on an overhead cam engine without removing the cylinder head. What tool is needed to prevent the valves from dropping into the cylinder?

Accepted Answer

A valve spring compressor and an air hose through the spark plug hole

Answer

When replacing valve stem seals in-vehicle, compressed air is introduced through the spark plug hole to hold the valves against their seats while the valve springs are removed. A valve spring compressor is also required to compress the springs and remove the keepers.