Engine Repair and Performance Flashcards

On an interference engine, what is the likely result of a broken timing belt while running?

Answer: Valves may contact pistons, causing bent valves

In interference engines, valves and pistons occupy the same space at different times, so lost timing causes contact.

When installing a new timing belt, the technician should first:

Answer: Align the crankshaft and camshaft timing marks

Timing marks must be aligned to keep valve and piston timing correct.

A hydraulic lifter ticks only for a few seconds after a cold start. Which is the most likely cause?

Answer: Lifter leak-down or oil drain-back

Lifters that leak down while parked tick briefly until oil pressure refills them.

Valve spring installed height is checked to ensure:

Answer: Correct spring pressure when the valve is closed

Installed height determines seated spring tension; shims correct excess height.

An interference angle in a valve job is typically achieved by grinding the valve face:

Answer: About 1 degree less than the seat angle

A 1-degree difference (e.g., 44° face on a 45° seat) gives a narrow, positive seal line.

Low oil pressure at hot idle with normal pressure at higher rpm most likely indicates:

Answer: Excessive bearing clearance

Worn bearings leak more oil, lowering pressure most noticeably at hot idle.

Before condemning an oil pressure warning light, the technician should first:

Answer: Verify actual oil pressure with a mechanical gauge

A mechanical gauge confirms whether the issue is real pressure loss or a faulty sender.