310S Engine Systems and Repair

Question 1

What is the primary purpose of the crankshaft in an internal combustion engine?

Accepted Answer

To convert reciprocating motion into rotational motion

Answer

The crankshaft converts the reciprocating (up-and-down) motion of the pistons into rotational motion that can be transmitted to the drivetrain.

Question 2

A compression test on a four-cylinder engine shows cylinders 1, 2, and 4 at 150 psi, but cylinder 3 reads 90 psi. What should the technician do next?

Accepted Answer

Perform a wet compression test on cylinder 3

Answer

A wet compression test adds oil to the cylinder. If compression rises significantly, the rings are worn. If it stays low, the issue is likely valves or a head gasket leak.

Question 3

What is the correct method for measuring crankshaft journal wear?

Accepted Answer

Outside micrometer at multiple points on the journal

Answer

An outside micrometer is used to measure crankshaft journals at multiple points to check for out-of-round and taper conditions, which indicate wear.

Question 4

What does excessive blue smoke from the exhaust at startup indicate?

Accepted Answer

Worn valve stem seals allowing oil to seep into the cylinders

Answer

Blue smoke at startup typically indicates worn valve stem seals. Oil pools on top of the valves when the engine is off and burns on the next startup.

Question 5

What is the function of the harmonic balancer on a crankshaft?

Accepted Answer

To dampen torsional vibrations in the crankshaft

Answer

The harmonic balancer (vibration damper) absorbs and reduces torsional vibrations generated by the power pulses of the engine, preventing crankshaft fatigue and failure.

Red Seal Auto Tech 310S Practice Test

Red Seal Auto Tech 310S Practice Test

310S Engine Systems and Repair