How to Confirm Engine Valve Noise?
4 Answers
Methods to confirm engine valve noise: 1. When the engine is idling, if there is a solid and crisp sound on the camshaft side that is more pronounced than the valve tappet noise and does not disappear during the "ignition cut-off" test, you can increase the engine speed to medium speed for testing. If the noise weakens or disappears, it may be a tappet noise; 2. You can remove the valve cover, make a wire hook, and test each tappet by hooking the adjusting bolt on the tappet. When hooking a certain tappet, if the noise weakens or disappears, it can be determined that the noise is coming from that tappet. Tappet noise is a light and crisp sound, which is a rhythmic intermittent noise, and the noise source is on the camshaft side; For side-valve engines, removing the valve cover makes the noise more obvious.
Just helped the neighbor guy check his old Jetta a couple of days ago. To listen for valve noise, find a quiet place to warm up the car until the engine reaches normal operating temperature, then shut it off. Use a long screwdriver as a stethoscope—press the tip against the valve cover and put your ear to the handle. Focus on the upper part of the cylinders. If the ticking sound changes with engine speed, it’s likely a valve clearance issue. If the noise disappears when the engine warms up, it might be oil not reaching the hydraulic lifters. This method is simple and can be done yourself, but be careful not to burn yourself.
The veteran mechanic at my family's repair shop taught me this trick: after starting the engine, open the oil filler cap and listen carefully. Valve ticking produces a crisp 'tick-tick-tick' sound, somewhat like the regular rhythm of a typewriter. If it's timing chain noise, the sound is duller with a rattling quality. You can lightly press the accelerator to test - if the noise speeds up with RPM increase, it's likely a valve issue. Pay special attention to older cars. We once had a 10-year-old Corolla with intake valve clearance 0.3mm too large - replacing the shim immediately made it quiet again.
Confirm the most accurate diagnosis in three steps: First, during a cold start, stand next to the wheel and listen—the valve noise is a high-frequency metallic tapping coming from under the hood. Second, use a stethoscope or metal rod pressed against the cylinder head, with your ear on the other end, to pinpoint the exact location. Third, after the engine warms up, disconnect the ignition wires one by one to test individual cylinders—the cylinder where the noise diminishes is the faulty one. Last year, my Golf had this issue—the exhaust valve clearance on the third cylinder was too large, measuring 0.4mm with a feeler gauge, double the standard. It’s advisable to prepare a 13mm wrench and new gaskets in advance.
