ASE A1 Engine RepairEngine Block AssemblyMedium
A technician is performing a crankshaft end play measurement. The service manual specifies an end play range of 0.002 to 0.007 inches (0.05 to 0.18 mm). The technician measures the end play as 0.015 inches (0.38 mm). Which component is MOST likely responsible for this excessive end play?
- AConnecting rod bearings.
- BCrankshaft counterweights.
- CMain bearing journals.
- DThrust bearings.
Show answer & explanationAnswer & explanation
Correct answer: D. Thrust bearings.
Excessive crankshaft end play is primarily controlled by the thrust bearings, which absorb axial loads. If the thrust bearings are worn or damaged, the crankshaft will have too much axial movement (end play).
Why the other options are wrong
- A. Connecting rod bearings affect the fit between the rod and crankshaft, not crankshaft end play.
- B. Crankshaft counterweights balance the crankshaft but do not control end play.
- C. Main bearing journals affect radial clearance, not axial end play.
Crankshaft End Play
Crankshaft end play is the controlled axial (front-to-back) movement of the crankshaft, primarily limited by the thrust bearings.
- Measured with a dial indicator.
- Excessive end play indicates worn thrust bearings.
- Too little end play can cause binding and overheating.
Memory trick: End play's too high? Thrust bearings say goodbye!