Valve Mechanism Noises

Valve Mechanism Noises Points : valve mechanism noises, engine noise analysis, problems in internal combustion engines, ic, engine, auto diesel Noisy valve, action has a characteristic clicking noise occurring at regular intervals. Inasmuch as the valves are operating at half crankshaft speed, the frequency of valve action noise is generally lower than that of other engine noises. To determine whether the noise is due to excessive valve clearance, insert a feeler gauge between the valve stem and the rocker arm or tappet. If the noise stops, the clearance is probably excessive and the adjusting screw should be readjusted. Never reduce the clearance to below factory specifications or the valve will bum.

Sticky valves can be detected by driving the car hard until the engine is well heated. Then quickly allow the engine to idle. A sticky valve will cause a pronounced valve noise, which will lessen gradually and sometimes finally disappear as the engine returns to normal operating temperature. The noise is accompanied by a rhythmic jerk due to the missing cylinder. As the noise disappears, so does the jerk, and the engine finally smoothes out as the valve seats. To locate a noisy hydraulic valve lifter, place a finger on each valve spring cap in succession. A distinct shock will be felt when the valve returns to its seat if the lifter is not functioning properly. If readjustment of the valve mechanism does not eliminate the noise, check the following:
1. Stick valves
2. Excessive clearance of tappet in block
3. Lower end of lifter scored or broken
4. Tappet screw pitted or worn uneven
5. Weak or broken valve spring
6. Inverted valve spring
7. Warped valve head
8. Valve seat not concentric with guide
9. Excessive stem-to-guide clearance
10. End of valve stem not faced squarely
11. Weak rocker arm spacer springs