Engine Noise Diagnosis

NOISE DIAGNOSIS

Momentary Noise When Engine Is Started

Condition normal. Oil drains from lifters which are holding valves open when engine is not running.

Intermittent Noise At Idle, Disappears As Engine Speed Is Increased

1. Dirt in lifter.
2. Pitted check ball.

Noise At Slow Idle Or w/Hot Oil; Quiet w/Cold Oil Or Increased Engine Speed

Excessive lifter leak down. Lifter should be replaced.

Noise At Idle, Becomes Louder As Engine Speed Increased To 1500 RPM

1. Excessive valve stem to guide clearance.
2. Off square valve spring.
3. Scuffed or worn valve tip/rocker arm pad.
4. Excessive valve seat or face runout.
5. Damper spring clicking on rotator.

Valves Noisy At All Speeds

1. Rotate crankshaft until piston of affected cylinder is at TDC of firing stroke.
2. Hold rocker arm against valve spring and check for valve lash by moving pushrod up and down.
3. If no lash is present, check for dirt in lifter or pitted check ball.
4. If valve lash is present, inspect pushrod and rocker arm for excessive wear and replace as needed.
5. If valve lash is present, and pushrod and rocker arm are satisfactory, lifter should be replaced.

Quiet At Low Speeds, Noisy At High Speeds

1. Incorrect oil level, oil foaming.
2. Clogged oil pump screen, bent pan or oil pump pickup.
3. Incorrect oil pressure.