Engine knock after rebuild.....need advice Options

[LCOX]

This on going problem started after I rebuilt my 1.8 engine last year. Since then I haven't driven the car and I've put it on the back burner and finally ready to face it again.

Rebuilt the 1.8 with all new bearings and new rings. There is a definite engine knock at idle and throughout the rpm range. This is not a ticking noise like a valve out of adjustment but a bottom end knock.

I did check valve adjustment and everything I could think of. When I pull the #3 spark plug wire the knock almost completely goes away but not completely but definetly better

A couple members said it was probably a rod knock so with the engine in the car I pulled the head and #3 piston and cylinder and tried another rod but the knock is still there.

So I guess take the engine apart and look for a mistake I made on the bottom end rebuild right? Anything else I can try? Thanks in advance. L

[worn]

This on going problem started after I rebuilt my 1.8 engine last year. Since then I haven't driven the car and I've put it on the back burner and finally ready to face it again.

Rebuilt the 1.8 with all new bearings and new rings. There is a definite engine knock at idle and throughout the rpm range. This is not a ticking noise like a valve out of adjustment but a bottom end knock.

I did check valve adjustment and everything I could think of. When I pull the #3 spark plug wire the knock almost completely goes away but not completely but definetly better

A couple members said it was probably a rod knock so with the engine in the car I pulled the head and #3 piston and cylinder and tried another rod but the knock is still there.

So I guess take the engine apart and look for a mistake I made on the bottom end rebuild right? Anything else I can try? Thanks in advance. L

I think it is interesting that the thing changes when you pull the #3 plug. That means I assume that the others do not affect the knock? That tells you that the compression gasses in #3 deform something that goes clunk in the day. The most obvious is #3 rod at the crank. Replacing the rod was heroic, but if you were not able to mic the crank at the time I think inconclusive since if it was undersized at the journal it would still be with a new rod. Were you able to see anything of interest after you got the piston out?


I can't see how not dropping the engine is going to get you anywhere. Seems like having the case on a stand is going to be easier than crawling over and under.

Two winters ago I did sort of the same thing. I did all my own measuring and even decked the heads myself. It was gamble all the way, doing the math and compression ratios with home-made jigs. No line boring because I couldn't detect a need with feeler gauges and a straight edge. All along I knew it might have to come back out. I hope it is in 50-100k miles though. As one poster pointed out though it could be a lot less. Best of luck.

One think you might use is one of those cheap stethoscopes. I was amazed using it when we lit the engine off - you can hear all the different parts doing their jobs and you can separate them out depending on where you touch the rod to. For anyone who hasn't tried it it, it is pretty wild. Have a go at it and see what you hear - at idle; for a short time.