ASE A1 Engine RepairCylinder Head and Valve TrainMedium
A technician is diagnosing an engine with a persistent ticking noise that is most pronounced during cold starts and tends to quiet down as the engine warms up. A stethoscope indicates the noise is coming from the top of the cylinder head. The engine uses hydraulic lifters. Which of the following is the MOST likely cause?
- AExcessive valve lash adjustment
- BA worn camshaft lobe
- CA bent pushrod
- DInsufficient oil pressure to the lifters
Show answer & explanationAnswer & explanation
Correct answer: D. Insufficient oil pressure to the lifters
Insufficient oil pressure, especially when cold, can prevent hydraulic lifters from fully pumping up, leading to excessive clearance and a ticking noise. As the oil warms and thins, or pressure improves, the lifters may pump up, and the noise subsides.
Why the other options are wrong
- A. Excessive valve lash is for solid lifters; hydraulic lifters self-adjust, and a ticking noise usually means they are not pumping up correctly.
- B. A worn camshaft lobe would cause a continuous ticking or misfire that typically would not quiet down significantly with engine temperature.
- C. A bent pushrod would likely cause a more severe and constant mechanical noise or misfire, not one that quiets down with engine warming.
Hydraulic Lifter Ticking
A common cause of ticking noise in engines with hydraulic lifters is insufficient oil pressure or a faulty lifter preventing proper 'pump up' and valve lash adjustment.
- Often worse on cold start
- May quiet down as engine warms
- Caused by lack of oil pressure or faulty lifter
Memory trick: Cold tick, warm silence, oil pressure's the dance.