When I took my exhaust manifolds off there was no gasket between the head and manifold at all. I thought there would have to be, but there isn't. What's the deal?

 

Have you scraped the head and the manifold? Sometimes its really hard to tell if there is one there or not.

And yes, it is supposed to have gaskets.

 

my car did not have gaskets between the head and the manifold either. It really suprised me.

 

Thats weird mine never had them either. I thought they might have hit the ground but i couldnt find anything. Mine has 46K miles and i know its never been apart. I guess gm was saving money.

 

I don't know why you guys didn't, but I sure did. They were different though. Each gasket just covers each port. Not just one long gasket.

 

mine didnt, all stock never hardly touched at all, had stock muffler, cats, etc...

manifolds dont need tham as far as i knew / heard from searching on here.

 

yep I didnt have any either.

 

mine didnt have them either

 

After taking the old 145K mile L98 out of my GTA, I was also suprised by the lack of exhaust manifold gaskets... Seemed untouched, must be factory (which would explain why the heat shields have all those stupid little tabs that keep the bolts from loosening! grrrr!)..

 

hmmm, I feel better now. I was really suprised to see the lack of gaskets, but I guess if the 2 surfaces are perfect you don't need any. I'm using them with my headers though.

 

Thats strange! Don't you need a gaskets to make sure it seals? Won't there be any exhaust leakage? My car is carbed...maybee that is the reason? Are all of your fuel injected?

 

I took my GTA to a muffler shop to sort out some exhaust leaks, and the guy told me that someone had put gaskets on the exhaust and that was causing the leaks.

He said the factory does not install gaskets on the exhaust manifolds, and every Chev SB car or truck with leaky manifolds, someone has always installed exh. gaskets, which shrink after time, and leak.

I didn't know either, but I thouht I'd just pass it along.

Troy
So Cal

 

Stock they don't have them, but I've always been told to install a set for reinstallation. No problems on any of the cars I've done (With manifolds at least, headers always seem to burn out after a while...)

 

Home come that is the case?

I have always been told that a good rule of thumb is that where there is metal to metal contact you have to use a gasket because no matter how good the milling job you can not exactly match the surface.

Is this wrong?

Or are the manifolds designed in some strange way that you don't need them?

 

I dunno That's what I thought too. Anyone know the answer?

 

You don't always need a gasket.. If the machine work is good enough, you won't have any leaks... One example would be the front pump in your 700R4's.. The pump halves mate together without a gasket (and it works good)...

 

I think the key here is the metals have to be the same type and thickness, in this case cast iron. If they are machined well, the thermal expansion should be equal between the parts. I don't know this for sure, but I'm betting aluminum head engines with cast iron manifolds will need gaskets.

Troy
So Cal

 

TA is correct. Headers will warp and flex as they go through their heat cycle. HEavy cast iron manifolds will not. Therefore they do not need gaskets because of simila mating materials and good machining.

 

i skimmed the thread, didnt see it mentioned.


stock iron head/iron manifold cars got no exhaust gaskets.

easiest way to tell is the factory put these annoying sheetmetal tabs on the bolts to keep them from loosening... if you have thoes tabs, theres a VERY good chance its factory.

 

Hummm....maybee that is what I had and I had mistaken them for gaskets...Did they have them over each port and they hang on the bolts?

 

Just adding to the topic that shifty is correct, no need for gaskets, and if you have some on there it's because somebody before you put them on. All of the sbc's with the stock logs that I have seen have never had gaskets, so it's not just a third gen thing.