I was hoping one of the engine gurus here could help me diagnose this funny sound that recently started on my V8. It's a TPI SBC with aluminum heads.

The trick is going to be trying to describe this sound in writing. It is coming from the right side of the engine, which is the rear side installed in my car, of course. It's either in the head or that exhaust manifold. Bear with me here. At low RPMs it's kind of a quick put-put-put-put sound but not a knock or a tap, really. At higher RPMs or under load it really kicks in with a fairly loud "raspberry" sound that seems to resonate through the exhaust, sounding kind of like a long mechanical fart, if you'll pardon my crudeness. It doesn't seem to be power draining or missing. I was thinking exhaust leak but if it is, I can't see where it's coming from. Plus, I'm not really sure what an exhaust leak sounds like.

If anyone needs more info, I will be happy to give you all I can. I'm going to go pull that valve cover in a few minutes, after it cools down a bit, to make sure I don't have a broken valve spring or something (not that I would know what that sounds like either).

Thanks for any help you guys can offer.

Sounds like a leak between your exhaust manifold/header and the cylinder head. Just my .02

Arn

PS, get some 1/4" surgical tubing and stick one end in your ear. Run the other end around the seams of your header and you will likely hear it.

[This message has been edited by Arns85GT (edited 11-12-2005).]

Do you still have the A.I.R. Tubes connected to the exhaust manifolds or do you have headers? If you still have the A.I.R. Tubes for the emissions, they usually connect to a valve before travelling down to the convertor (on a regular car)

If you still have the tubes connected and still have the valve, it sounds like the noise you get when the valve goes bad.

Like you said, Kind of hard form a worded description but when these A.I.R. tubes leak, either at the valve or at the 4 connections at each head. they can makes some pretty funny "raspy" noises. Just another area to check. (Of course, if you are no longer using the tubes on your engine, this would not apply.

Arns may have nailed it. I decided to remove the manifold, which is a ram-horn by the way so no A.I.R. stuff, and before I had the bolts all the way out, a hunk of gasket from around the center two ports fell on my face. It does appear to have been leaking from that area. That center area of the gasket was VERY brittle.

I went to the parts store to get a replacement, but they were not in stock so it will be in the morning before I get to put it back together and see if that does the trick. I'll update as soon as I get it back together in the morning. Thanks guys.

Yes, first thing I thought of was a bad exhaust manifold gasket

Most exhaust manifold leakes sound like a "Ticking" noise

maybe spent a few extra $$ and get the good copper gaskets there not cheep but you shouldnt ever have to dink with them again