exhaust manifold gaskets.

i recently had the heads milled and refreshed and upon taking the headers off i noticed they did not come from the factory with gaskets? upon reinstalling the heads i put felpro header gaskets and now i have a leak from the rear head? man! has this happened to anyone here? are they supposed to go back on without gaskets?

My exhaust manifolds came with OEM gaskets. When I upgraded to headers, I used the supplied gaskets that came with them. No leaks.

damn! the are leaking from the #2 exhaust i ordered a new set lets see what that fixes...tanks AA!

They are supposed to go back on with metal gasket's, preferably OEM metal ones.
Some of the aftermarket gasket are prone to blowing out very easily.
The custom exhaust shop i dealt with for some parts warned me ahead of time, before I put the headers on, about the gasket issue.
I was going to use the ones that came with the SSAC headers but when i showed them to him he guaranteed they would leak and showed me why and sold me a set that won't leak.
Basically the gasket area around the exhaust ports have to have a ring of crimped metal in that area or else exhaust pressure will just blow out the gasket in a short amount of time.
Other people on here have experienced the problem also.
Need premium gaskets or GM OEM.

man! thats good to know and bad to know all at once! aftermarket can suck. guess im going to gm to bend over happily. better put on my dancing shoes

Make sure the OEM's are all metal. I haven't seen what they look like but it was explained to me and I think I have a good mental picture.
Or you can try and find a Speed Shop that might be able to get you quality header gaskets for a 3800. That could be difficult. I don't know.
My car had no gaskets on it when I took the stock manifolds off.
I've heard through a couple of sources that that is not all that uncommon.
The heads and manifolds must have been machined to a strict tolerance for no gasket to work.

so...would u recommend just tightening it if theres a slight leak? or adding a gasket?

I would say installing a good quality gasket would be the best solution.
If there is a small leak it is probably because the manifold has developed a small amount of warpage over time. Heat cycles (hot - cold -hot - cold) continuously over a period of time will make a perfectly flat iron surface not so flat anymore.

i called the gm dealer and they have no part# for a riv. the parts guy sed metal to metal is how it is! i find that hard to believe. but im not going to argue. its too hot. vato zone has fel-pro maybe ill get lucky with the 2nd set. the first was kicking around the shop awhile before i got around to doing the heads. ill keep searching for a better replacement though....

ZZP has both Fel-Pro and OEM GM exhaust manifold gaskets. If you look at their picture of the OEM ones you can see that they have the the metal ring bonded around all exhaust ports.
They may not be listed by GM for the Riv, but they are listed for other 3800's and they fit.
Those are the one's I would get.

thanks for that r.w. i called the dealer and they have 1.gasket going for $16.66 . man thats pricey. its a stainless steel 1 for a 98 bonnie with crimped rings. beaut! but they only have 1 side? man..dat sux. but i only have the 1 side leaking soo..

Buy the one and have them order the other or wait and order from ZZP.

i am going to order a set it seems from zzp. i think that that will solve the leak. thanks rw!

Did you get a price from monsterpartsonline.com?

Don't know the OEM P/N to use to look it up.

I"m pretty sure series I has different manifolds than the series II so the gaskets will most likely be different. I'm pretty sure the ones at zzp are for series II/III.

they are different...the spacing is more awkward

(OO O)
series 1

and
(O O O)
series 2

yeah different. still looking in this case. i doubled up on the fel-pro crap and that didnt solve the leak. apparently the manifold is warped? how in hell didthat happen? i have not a clue?

I didn't notice you had a Series 1 engine, sorry.
The ZZP parts are for series 2 and 3 only. Hope you didn't already order a set.
From a previous post:
If there is a small leak it is probably because the manifold has developed a small amount of warpage over time. Heat cycles (hot - cold -hot - cold) continuously over a period of time will make a perfectly flat cast iron machined surface not so flat anymore.

oooo rick! i thought u paid attention to detail!!
look what section its posted in lol

You can try a new gasket with some very high temp rtv, the orange/red stuff.
That should help eliminate the leak.
Doubling up on gaskets will not work as you have found out.
Need to see if that metal gasket your dealer has is for the series 1 engine.
If it is grab it.

no sweat r.w. checked it out first and no dice. ill try the goop. otherwise ill have to find a machine shop that will plane the manifold . a new one costs $300 and change!

Make sure you let the RTV cure before starting the engine!!!

just curious...how did u test to see ur exhaust manifold was leaking?

robotennis61 wrote:

no sweat r.w. checked it out first and no dice. ill try the goop. otherwise ill have to find a machine shop that will plane the manifold . a new one costs $300 and change!

Any reasonably equipped automotive machine shop will have a surface grinder to do that job.
It is the same equipment used to resurface say a flywheel or cylinder head, etc.
Shouldn't cost too much.
But i think you can solve your problem with a gasket and sealant and save some time, money and aggravation.