Exhaust Leak "Tick" from Manifold/Header

[21again]

I've got an exhaust leak/tick coming from the header connected to #4 & 6 cylinder. Is there a gasket between the header pipes and the block? It looks like there isn't one, I can't see one listed in the manual either. All the header bolts are tight. (Gee that was fun checking them -- pita) '81 / L81 Bone Stock

 

[Vader]

There are foil/compressed ceramic fiber laminated gaskets in those locations.

Another thing to consider is the A.I.R. tubes in that same area. The stainless material used for the manifolds is a 400-series, containing some iron, so they WILL rust eventually. And who knows what alloy was used for welding the air injection tubes in place originally?

I found four out of the eight leaking (rusted off) and had to weld the tubes shut to prevent leakage. No more annoying "tick".

 

[21again]

Vader...

...thanks. I'll check again to be sure it's not coming from the A.I.R. pipes. Did you just completely remove the A.I.R. pump then?

 

[Vader]

The injection pump was removed by Bubba (the previous owner). I only closed the tubes that were leaking. The A.I.R. checks are still in place and the system can be reinstalled if necessary. Air would be pumped to the remaining open tubes and make it into the manifold either way. If I were to reinstall teh injection pump, I'd probably get an electric pump from a later LT1 and run it briefly in open-loop mode only, just like the LT1s.

 

[Tom Bryant]

Several years ago the AIR check valves rusted out on the bottom. Probably from sitting too much. Anyway they were't going to come off of the manifolds without heat so I got the pleasure of removing those tubing manifolds(headers) from the car. I can't remember if the original gaskets were the same as the replacements from GM but it blew me away when I saw the replacements. Chevrolet and others had included those same foil over compressed fiber gaskets in every overhaul gasket set I ever bought clear back into the early '60s. Even the ones for '55 and '56 265 inch engines. Of course I never used them on iron manifolds so I had a bunch of them in my misc. gasket box. I had thought of trying to use those old gaskets I had in stock but though better of it and ordered what the book called for. I don't know what I expected to see but that took me by surprise when they were the same thing.

One thing for sure is that they don't leak like regular header gaskets will over time.

Tom