MarcR94v6

From between 1100 rpms and 2000 rpms I can hear this clanking sound when cold and warm/operating temp, sound like rockers but I'm unable to determine which side it's coming from. It seems like it goes away above 2k, but I'm not sure if I just can't hear it over exhaust. I just bought this car in northern california and drove it down to San Diego, where it began running too hot the longer I drove it and I decided to have it towed home. Even though it never went in the red, I'm hoping the heat didn't damage anything. Turned out to be a bad waterpump which was fixed under aftermarket warranty at a GM dealer. I also had them change the oil and when I picked it up I noticed the noise at low rpms that very same night.

I don't drive the car hard and there was no high rpm event that I can point to as the cause. oil pressure is good everywhere warm and cold.

Here are some videos:

On the first one you can hear it really good 49 seconds into it.

[autostream]http://autostream.com/camaroz28/?page_type=firebirdplayerthumbnail&framepage=2721& transactionid=1350261849-72130154253&posted_by=MarcR94v6_www.camaroz28.com& youtube_video_id=1tqSVyNaano[/autostream]



Does this sound bad to you guys?

MarcR94v6

2nd vid

[autostream]http://autostream.com/camaroz28/?page_type=firebirdplayerthumbnail&framepage=2722& transactionid=1350262022-72130154253&posted_by=MarcR94v6_www.camaroz28.com& youtube_video_id=_djJKMQfFTA[/autostream]

rv93

i think its piston slap. i have the same thing, but it goes away once the engine is warm.

MarcR94v6

This doesn't go away when warm. I took it to a pretty good shop I think I can trust, both techs have 30 years experience and they don't think it's abnormal. He actually says it's warm piston noise. It makes me feel a little better but sometimes the noise freaks me out. I guess I can always get a 2nd opinion but it'll be hard to tell if they just wanna tear the engine down to make some money, this place could have done it easy as it has a short warranty, but they didn't.

WhiteHawk

You could pull the valve covers and check to see if all your rockers are tight or if there are any other issues. The older LS1's had problems with the needle bearings coming out of the rocker arm, but I had thought that was mostly on 98's. You just have to pull the coilpacks and then the valve covers pop right off.

-Geoff

rod442

Not common, but my 2000 had a bad lobe on the stock cam. porous casting, broke the edge right off. Took me untill we pulled the motor for a forged shortblock, to find it.

I had already replaced the rockers, pulled the heads, and installed new lifters and didn't see what would have been making the noise. So we figured it might be in the bottom end, and ran with it. It never did "blow up".

After CAREFULLY inspecting the oem lifters, we found the one that had slightly knurled the edge on the roller. It almost needed magnification to see it. So, basically I didn't drive it long enough when it starting making noise. Should have driven it untill it was obvious.

Which is the moral of my post. If it performs ok, run it untill you know something wrong. AFTER doing the basic checks. pull the tappet covers and take a look at stuff (ie rockers). maybe even check for a bent pushrods, and look at the springs when its apart.

If you dont find anything, run it. It will either stay the same, or become obvious.

MarcR94v6

Thanks for the replies. I removed the driver's side already and found nothing. Very slight side to side movement of the rocker body, zero up and down movement. I'm assuming if a lifter was collapsing I would be able to push the rocker arm body down on the pushrod side? I tried to spin the pushrods like I could in my old LT1, but it's too tight in the LS1, though I could tell there was no slop in the pushrods on that side.

rod442

Manual or automatic? no slop in the pushrods doesn't mean none are bent. have to pull them (all) and roll them on a smooth (glass, etc) surface to check if any are bent. This is less likely in an automatic car, but I'd check it anyway; since its so easy to do.

Oh, and for a tip on the pass side coil pack bracket (or both); notch the last bolt hole so all you have to do is loosen the bolt and slide it forward to get it out of the car. Cuts down on the headache, on that side.

Otherwise chalk it up as lifter noise, or piston slap, or some other noise that will either never get worse - and run fine; or will make itself "known" eventually. Then worry about it.

MarcR94v6

It's an automatic, I forgot to put that in my sig, updated now.

WhiteHawk

I just leave that back one out!

-Geoff

ACE1252

Take a mechanics stethoscope to it and try to determine which cylinder it is coming from....very well could be a lifter starting to have trouble.