350 Exhaust gasket problem

Hey all,

I have a 79' HD Chevy 3/4 ton truck with a 350. I recently installed a dual exhaust system, but kept the stock manifolds. Anyway, my problem is that after about 500 miles the doughnut gasket at the manifold/downpipe connection is blown out (both sides).

So in the newsgroups opinion, what most likly did I screw up? Too tight? Not tight enough?

John

Reply to
John Wilentz
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Were they a fiber or steel gasket? The newer vehicles do better with the steel gaskets due to elevated engine temperatures.

Brian

Reply to
el Diablo

Were they connected with the bolts AND springs? Is your exhaust hung in at least three places by flexible rubber mounts?

Doc

Reply to
"Doc"

The 79 uses the three studs with the flange:

No springs. Do the pipes have a nipple for the donuts to fit on, or are the donuts just free riding between the pipe and manifolds?

If that's the case, you'll have to get a piece of pipe small enough to slide in the pipe at the 39 degree Chevy flare on the pipe, then the donuts won't be grinding away between the manifold and pipe.

I hope this helps?

Refinish King

Reply to
Refinish King

Hmm,

I used the fiber gaskets. I think what came out was one fiber and one steel. This item may bear futher investigation.....

John

Reply to
John Wilentz

Springs?

and

Yes.

John

Reply to
John Wilentz

hmmm This too merits investigation. Although as I recall the old pipes I took off didn't have any kind of inner lip for the gasket either. Of course, that doesnt mean one wouldn't help! Perhaps a combination of this and the sintered metal doughnut gasket will make for a truly bulletproof connection.

Oh well, at least nothing has had the chance to corrode yet really so it should be nice and easy to take back apart......heh...crap.

John

Reply to
John Wilentz

Never seen those before eh? They go on the stud before the nut.

Doc

Reply to
"Doc"

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