Plagued With Exhaust gasket leaks [message #270952] |
Sun, 01 February 2015 12:31 |
Neil
Messages: 271 Registered: July 2007 Location: Los Angeles and Magalia, ...
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Is there any particular reason why the driver's side of the motor is more prone to developing an exhaust leak in the center of the manifold?
I do have Thorley headers. With a new gasket everything is fine for anywhere from 300 to 2,000 miles, then I get a leak. This time it is dead center of the flange.
The passenger side does not seem to have this problem. Could it be a warped flange? But then why would it snug up and work for a while?
Thanks for your thoughts.
Neil
76 Eleganza now sold
Los Angeles
[Updated on: Sun, 01 February 2015 12:31] Report message to a moderator
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Re: Plagued With Exhaust gasket leaks [message #270953 is a reply to message #270952] |
Sun, 01 February 2015 12:47 |
jtblank
Messages: 237 Registered: June 2007 Location: Tulare, CA
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Use rim flex gaskets, you'll never have problems again. Your flange may not be true so when you have it off you could have it surfaced. I had same thing, leaks develop over time but since using rim flex never again, it's been at least 6 years since I changed. You can get them from one of the Jim's or from Rim Flex direct but price is about the same, so I buy from GMC vendors.
You can read about them at http://catalog.remflex.com/
Hope this helps!
John Blankenship
'76 Palm Beach
Tulare, CA
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Re: Plagued With Exhaust gasket leaks [message #270985 is a reply to message #270952] |
Sun, 01 February 2015 18:47 |
jhbridges
Messages: 8412 Registered: May 2011 Location: Braselton ga
Karma: -74
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My hotrod toad (88 Ranger, strung out 302 CID engine) suddenly developed an appetite for exhaust gaskets. The side with the cut apart flanges lasted marginally longer than the solid side, but not much. Some poking about showed that an exhaust change I made required shortening the exhaust pipe between the headers and the mufflers by a couple of inches, changing the 'twist' factor under acceleration. Additionally, the left motor mount loosened, allowing the engine to move about a bit more. The combination let the header flanges move - or at least try to - due to the lever action of the headers and pipes and the way they're mounted on hangers at the rear of the pipes and in front of the mufflers.
Bottom line - make sure your engine mounts are tight and the engine isn't moving about more than it should. It won't take much, the exhaust system on these coaches is fairly rigid towards the rear.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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Re: Plagued With Exhaust gasket leaks [message #270986 is a reply to message #270952] |
Sun, 01 February 2015 18:51 |
Chris Tyler
Messages: 458 Registered: September 2013 Location: Odessa FL
Karma: 7
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I have been a big believer in copper gaskets with permatex spray copper sealer amd locking bolts.
These Remflex gaskets are worth a look.I have a small leak myself on the driver side with Thorley headers
Sanderson headers have a bead, they recomend permatex high temp silicone only. Im about to put a set on my lincoln 460.
Curious...has anyone used the Sanderson SS shorties on the GMC?
76 Glenbrook
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Re: Plagued With Exhaust gasket leaks [message #271082 is a reply to message #270952] |
Mon, 02 February 2015 20:09 |
Bob de Kruyff
Messages: 4260 Registered: January 2004 Location: Chandler, AZ
Karma: 1
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Neil wrote on Sun, 01 February 2015 11:31Is there any particular reason why the driver's side of the motor is more prone to developing an exhaust leak in the center of the manifold?
I do have Thorley headers. With a new gasket everything is fine for anywhere from 300 to 2,000 miles, then I get a leak. This time it is dead center of the flange.
The passenger side does not seem to have this problem. Could it be a warped flange? But then why would it snug up and work for a while?
Thanks for your thoughts.
Are you still running two mufflers? If so, are they matched and not rusted and plugged so that both have equal back pressure?
Bob de Kruyff
78 Eleganza
Chandler, AZ
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