ASE G1 Auto Maintenance and Light RepairManual Drive Train and AxlesMedium
A client complains that their vehicle with a manual transmission feels sluggish and the engine RPMs rise significantly without a corresponding increase in vehicle speed, especially when accelerating uphill. The clutch pedal free play is within specification. Which of the following is the MOST likely cause?
- AAn incorrectly adjusted clutch master cylinder pushrod
- BA seized pilot bearing
- CA worn or oil-contaminated clutch disc
- DA broken clutch release fork
Show answer & explanationAnswer & explanation
Correct answer: C. A worn or oil-contaminated clutch disc
The symptoms of engine RPMs rising without vehicle speed increase, especially under load, are classic signs of a slipping clutch. A worn or oil-contaminated clutch disc reduces the friction needed to transmit power effectively.
Why the other options are wrong
- A. An incorrectly adjusted clutch master cylinder pushrod could cause either insufficient disengagement (hard shifting) or constant slight engagement (premature wear), but typically not the degree of slippage described if free play is correct.
- B. A seized pilot bearing would cause noise or difficulty shifting, not clutch slip.
- D. A broken clutch release fork would prevent clutch disengagement, making it difficult or impossible to shift gears, not cause slippage.
Clutch Slippage
A condition where the clutch disc fails to fully engage with the flywheel and pressure plate, causing power loss and engine RPMs to rise without vehicle speed increase.
- Caused by worn friction material, oil contamination, or weak pressure plate.
- Symptoms include high engine RPMs without acceleration, burning smell.
- Often worse under heavy load (uphills, acceleration).
Memory trick: Slip 'n' slide means no grip inside.