About two months after replacing the vacuum pump, a sharp "ticking" sound started that seemed to come from the front of the engine, and that varied directly with the engine speed. Checking the power steering pump reservoir revealed it was about half full. I added fluid but the ticking was still there.
The next thing I did was to adjust the valves. While turning the engine by hand for this procedure, I noticed a sharp-but-hollow sounding "pop" coming up from deep inside the engine at the timing chain. The sound occurred at what seemed to be every complete revolution of the engine. It may have been every half-revolution, but in any case, the "popping" was occurring at consistent points in the rotation of the engine. I know the vacuum pump opens up into the crankcase...
Any ideas what this noise is and what it means? Thanks in advance!
Wayne
Annandale VA