General Engine Diagnosis Flashcards
6 cards from real ASE4 practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 General Engine Diagnosis flashcards as text
An engine has a wet compression test reading significantly higher than the dry test. This indicates:
Answer: Worn or damaged piston rings
Adding oil temporarily seals worn rings, causing a wet reading much higher than the dry reading.
A vacuum gauge needle fluctuates between 14 and 19 in-Hg at idle. This suggests:
Answer: An intermittent misfire or sticking valve
A fluctuating vacuum needle at idle indicates an intermittent problem such as a sticking valve or random misfire.
During a cylinder balance test, disabling cylinder #5 drops RPM by 50 while all others drop by 200. This indicates:
Answer: #5 is weak and contributing less power
A smaller RPM drop on one cylinder compared to others means that cylinder is contributing less power than the rest.
A technician hears a rhythmic tapping noise that increases with engine speed. Oil pressure is normal. The MOST likely cause is:
Answer: Excessive valve clearance
Excessive valve clearance creates a rhythmic tapping that speeds up with engine RPM and is unaffected by oil pressure.
A customer reports an engine knock that worsens under load but disappears at idle. This MOST likely indicates:
Answer: Rod bearing knock
Rod bearing knock intensifies under load because increased combustion pressure amplifies the bearing clearance impact.
When testing cranking vacuum, the gauge reads 0 in-Hg on all cylinders. The MOST likely cause is:
Answer: A jumped timing chain or belt
Zero cranking vacuum across all cylinders indicates the valve timing is completely off, typically due to a jumped timing chain or belt.