Exhaust Manifold Leak Again - The 1947 - Present Chevrolet & GMC Truck Message Board Network

ramz · 10-09-2011, 03:06 PM

I just replaced the gasket about 2 months ago now it seems to be leaking again. Any ideas why they would go out again? Too hot? warped manifold?

notyo_cheez · 10-09-2011, 03:23 PM

Weak motor mounts? A flexing power/drive train due to bad mounts may even crack exhaust manifolds. Worth a look...

79k30dually · 10-09-2011, 05:40 PM

Make sure manifolds are flat, surfaced. Buy GM stainless exhaust gaskets, use new bolts, no leaks, Ron

lilpoindexter · 10-09-2011, 06:27 PM

Some dude recommended Nord-Lock washers at work for some other application...I used them in my goofy integrated head straight six when the gasket blew out...I don't have that many miles on it, but so far so good. I think if the bolts start to loosen, then more heat gets into that part of the joint, cooks the gasket, then the joint gets bigger, more heat passes by, until the gasket is cooked and blown out. The keys are flat mating surfaces, and keep a tight clamp between sealing surfaces.

raceman6135 · 10-11-2011, 07:28 PM

Are you talking about the gasket between the exhaust manifold and the head, or between the exhaust manifold and the exhaust pipe?

I quit trying to get a gasket to live between the manifold and the head. As long as the surfaces are clean and flat, the cast iron manifold will expand at a very similar rate to the cast iron head and it will not leak.

If you're talking about between the exhaust manifold and the exhaust pipe, you have to make sure that the mating surfaces are clean and straight, and that the proper gasket is being used. Some have a collar and some don't. And of course there are different diameters.

On my 1986, I've kept the vacuum operated valve in the exhaust to assist with quick warm-ups, so between the cast iron exhaust manifold and the cast iron butterfly valve assembly, there is no gasket and I've had no problems in 15 years.

ramz · 10-11-2011, 09:33 PM

I'm talking about between the exhaust manifold and the head. I used the paper/aluminum gasket. I'm going get the me all aluminum gasket this time.

Hubscrub · 10-11-2011, 09:49 PM

i've never used a gasket between the head and a stock manifold without problems. Matter of fact only leaks there i've had is on ones the PO used the gaskets.

raceman6135 · 10-12-2011, 06:53 PM

Quote:

Originally Posted by Hubscrub

i've never used a gasket between the head and a stock manifold without problems. Matter of fact only leaks there i've had is on ones the PO used the gaskets.

QFT.

Don't run a gasket between cast iron heads and exhaust manifolds.

ramz · 10-15-2011, 11:28 PM

Well it wasnt the exhaust manifold it was the doughnut on the exhaust.

10-09-2011, 03:06 PM	#1
ramz Registered User Join Date: Jul 2011 Location: Dallas, TX Posts: 205	Exhaust Manifold Leak Again I just replaced the gasket about 2 months ago now it seems to be leaking again. Any ideas why they would go out again? Too hot? warped manifold?

10-09-2011, 03:23 PM	#2
notyo_cheez Registered User Join Date: Apr 2011 Location: corpus christi, tx - america's fattest city Posts: 253	Re: Exhaust Manifold Leak Again Weak motor mounts? A flexing power/drive train due to bad mounts may even crack exhaust manifolds. Worth a look...

10-09-2011, 05:40 PM	#3
79k30dually Registered User Join Date: Aug 2011 Location: Newark Ohio Posts: 122	Re: Exhaust Manifold Leak Again Make sure manifolds are flat, surfaced. Buy GM stainless exhaust gaskets, use new bolts, no leaks, Ron

10-09-2011, 06:27 PM	#4
lilpoindexter Registered User Join Date: Sep 2010 Location: los angeles Posts: 1,134	Re: Exhaust Manifold Leak Again Some dude recommended Nord-Lock washers at work for some other application...I used them in my goofy integrated head straight six when the gasket blew out...I don't have that many miles on it, but so far so good. I think if the bolts start to loosen, then more heat gets into that part of the joint, cooks the gasket, then the joint gets bigger, more heat passes by, until the gasket is cooked and blown out. The keys are flat mating surfaces, and keep a tight clamp between sealing surfaces.

10-11-2011, 07:28 PM	#5
raceman6135 Dino burner Join Date: Nov 2002 Location: Calgary, Alberta, Canada Posts: 602	Re: Exhaust Manifold Leak Again Are you talking about the gasket between the exhaust manifold and the head, or between the exhaust manifold and the exhaust pipe? I quit trying to get a gasket to live between the manifold and the head. As long as the surfaces are clean and flat, the cast iron manifold will expand at a very similar rate to the cast iron head and it will not leak. If you're talking about between the exhaust manifold and the exhaust pipe, you have to make sure that the mating surfaces are clean and straight, and that the proper gasket is being used. Some have a collar and some don't. And of course there are different diameters. On my 1986, I've kept the vacuum operated valve in the exhaust to assist with quick warm-ups, so between the cast iron exhaust manifold and the cast iron butterfly valve assembly, there is no gasket and I've had no problems in 15 years.

10-11-2011, 09:33 PM	#6
ramz Registered User Join Date: Jul 2011 Location: Dallas, TX Posts: 205	Re: Exhaust Manifold Leak Again I'm talking about between the exhaust manifold and the head. I used the paper/aluminum gasket. I'm going get the me all aluminum gasket this time.

10-11-2011, 09:49 PM	#7
Hubscrub Cruzin Join Date: Dec 2009 Location: on the road Posts: 2,835	Re: Exhaust Manifold Leak Again i've never used a gasket between the head and a stock manifold without problems. Matter of fact only leaks there i've had is on ones the PO used the gaskets. __________________ Lime Wife's 67https://www.google.com/url?sa=t&rct=...wZEMODaS2d94u8 Back to the Fifties 59 https://www.google.com/url?sa=t&rct=...NAeStpydfrcj_U Proverbs 3:5,6 "Thanks to the Interstate Highway System, it is now possible to travel across the country from coast to coast without seeing anything."Charles Kuralt In memory of our first baby daughter, daddy and mommy love you. Danica Grace 6/26/14

10-15-2011, 11:28 PM	#9
ramz Registered User Join Date: Jul 2011 Location: Dallas, TX Posts: 205	Re: Exhaust Manifold Leak Again Well it wasnt the exhaust manifold it was the doughnut on the exhaust.



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