I can't figure this one out... it only happens at idle or low rpms, with little to no load on the engine, such as when coming to a stop or just idling. It has only occurred twice before since I got the engine together, but it did happen tonight and it just sounds nasty.

The sound.... think like a fork or a bottle cap stuck in a garbage disposal. This awful metallic 'clanging' type noise that sounds like it's coming from inside the engine. It isn't rythmic like a rod knocking or anything.
At first I thought it was some bad detonation, but my understanding is that usually occurs under load if it's going to happen, not at idle. If was detonating I would think it would get worse when you put some load on the engine, but it disappears when you give it a little throttle.
Another thought was maybe the oil pickup came loose and was rattling around occassionally in the oil pan. My oil pressure is fine though.

Today I pulled the valve covers and re-lashed the valves. didn't see anything out of the ordinary. Oil looks fine, no metal in it.

any ideas?

If you have an automatic trans, it may be a cracked flex plate. They can crack around the screws that attach it to the crankshaft and they do make a lot of nasty noises.

Like Jwagner said, I had one crack in my suburban I thought the rod bearing went, it would only do it at low Rpm or idle, and go away when the motor reved a little. I also had a converter go bad in the camaro, sounded bad at low rpm I unbolted the converter checked the flexplate for cracks, fired the motor up and there was no noise, figured it was the converter and it was. Jim

If you have an automatic trans, it may be a cracked flex plate. They can crack around the screws that attach it to the crankshaft and they do make a lot of nasty noises.

I hadn't thought of that, but I do have an automatic, and I re-used the flexplate that was with the shortblock when I bought it (supposed to only have 4000 miles on it). If that's the case, I don't look forward to that repair!! At least it is fairly inexpensive though. The converter is brand new.

What does it sound like if rockers are hitting the valve covers? I would expect more of just a 'tap' and not a ringing metallic type sound like I'm hearing, but I don't know.

Could just be loose converter bolts. Thats what happened to me about 6mo ago. Just tightend them back up and no problems.

David

Could just be loose converter bolts. Thats what happened to me about 6mo ago. Just tightend them back up and no problems.

David

I would be thrilled if that's all it is! I'll check tonight if I get time.

After a quick inspection, I have a couple of converter bolts that are about ready to fall out! I guess that would explain the noise. I'm glad it did'nt just come completely loose!

thanks for the suggestion guys, I wouldn't have thought to look there otherwise.

Are you using a cam button?? When my cam went flat, the button was hitting the timing cover.. If you have a long water pump, you can actually just put your finger in the center of the cover & feel if it's hitting..

Mine kind of sounded like a cow bell, for lack of better discription..

Scott

Are you using a cam button?? When my cam went flat, the button was hitting the timing cover.. If you have a long water pump, you can actually just put your finger in the center of the cover & feel if it's hitting..

Mine kind of sounded like a cow bell, for lack of better discription..

Scott

No cam button, it's a solid flat tappet...

Glad you were able to track the noise down. :)

David

Doh, I didn't see the post where you said that you found the problem :clonk: :clonk:

Allright Brian!
Can't ask for a cheaper fix than this!