Could someone explain what an engine knock should feel like? At idle speed? I'm heading out now, but when I get back later, I'll explain more. '85 32 valve FWIW.

 

Just like it sounds. Knock, knock, knock. Like a hammer wrapped in a thin rag and rythmically struck against dense metal.

 

Wow...very well described you should be a sound man for the movies.

 

If it's your car you can feel it very clearly in your stomach.

 

Mine started doing the same thing. I hope it is a stuck lifter and will try Wynn's hydraulic lifter oil or reislone. Not a good feeling.

Glenn

 

Glenn -

Which car? I hope the Wynn's eliminates the problem.

 

It's easy to tell a lifter knock to a rod knocking by it's location (..at least on a 32v). The sound from the lifter is from the top of the engine.

Get a big screwdriver and use it as a stethoscope.

 

I DOUBT you have detonation at idle, and if you do then something is seriously out of wack, the reason I say this is that you can run alot more advance at idle without detonation. At idle the risk of detonation (or preign) is very very minimal

 

And your wallet, if it is a bottom end knock.

 

There are several knocks....pinging predetonation is poor gas under acceleration sounds like "marbles rattling around" a less than metal on metal . Rod bearing knock is the hammer on metal in the crank case BUT BIG but it changes tone as you rev the engine and decelerate it. The third pounding is when the engine eats something like a washer or a bolt that is a solid constant pounding on the top end with little change when loading unloading the engine it simply is there all the time ! And Yes I have heard all these in a 928

 

Maybe adding the sound of the tappets if they are damaged or starving oil: it sounds like a really loud ticking or "knocking" sound. Unlike the real knocking of the engine which happens under load, this is loud when idling, and matches the engine rpm.

 

Right the lifters just kinda rattle click click on start up then often get quiet ....the old very brown 1980 if it sits for a week or two does this . One of the GTS cars we had here tended to do that too.