Engine Tapping Noise

Tapping noise from the engine is often caused by a stuck hydraulic lifter. A bad lifter is not necessarily a huge problem and if you are driving an older vehicle you may wish to just ignore the noise if the engine is otherwise perfoming well. Increasing the frequency of your oil changes may help to clear up the issue but if the noise persists you will need to replace the lifter to eliminate the sound.

The above noted, if your tapping sound is accompanied with engine vibrations or backfires, you may be facing a problem more serious than a stuck lifter.

1. Tapping and Vibrating
If the tapping in your auto's engine is accompanied by a persistent vibration or noticeable tremors under load, you may have damaged the rocker-arms or valve push rods. To check the problem you will need to remove the valve covers and visually inspect the arms, rods, and valve stems. Oftentimes the repair is nothing more than replacing the broken rod or arm and bolt.

2. Tapping and Backfire
Though much less likely, if your auto happens to also be backfiring while tapping, you may have a damaged camshaft. This will not be something you should attempt to diagnose yourself, and it will be a fairly costly and laborious repair. If you suspect a bad camshaft, take your auto to a reputable mechanic or dealer and get the cam tested. Before leaving your vehicle, get a full estimate (in writing) and for the repair itself, and for the testing and reassembly should you decide to decline the repair.

If you do go ahead and replace the camshaft, you should also replace all of the lifters as well. Further, this is an opportune time to replace your timing chain or belt.

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