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Traced down that elusive exhaust leak!

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Patrick67BJ8

Patrick67BJ8

Obi Wan
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Ever since I put my car back on the road in 2012, I have been had a small but noticeable exhaust leak from the down pipes to exhaust. I replaced the triangular shaped exhaust manifold gaskets, twice, and redid the mufflers to down pipes three times. Engine issues made it necessary to remove the Head for a valve job and cleaning up the engine bay I spotted the leak area. I finally was able to pinpoint the cause, I think, to the thread lengths on the rear exhaust manifold. All of the studs were replaced by a machine shop and the non-threaded area was different on one of the studs. So, all of the new gaskets and proper tightening was in vain.
 

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Good eyes. I'd never have caught that. But seems weird that the threaded lengths are different on the same part. Looks like the one in the rear is different too.
 
NutmegCT said:
Good eyes. I'd never have caught that. But seems weird that the threaded lengths are different on the same part. Looks like the one in the rear is different too.
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I am going to replace them or use a die to add more threads to correct them. Maybe use a washer for a spacer and call it done.

The triangular exhaust manifold gasket had the signs of two exhaust leaks that lead me to the studs.
 
Newer gaskets aren't particularly effective either (no asbestos?). I've never had much luck with the spec'd brass nuts; I put high-temp anti-freeze on the threads and double-nut them, and smear high-temp silicone on the gaskets. If you can, it's a good idea to flat-file the mounting surfaces.

On one long road trip I would start the day under the car with a ratchet, a couple long wobble extensions and a deep socket. That got old in a hurry.
 
Nice find. Very observant. Would High Temp Copper RTV heat to better seal the area? It's likely similar in function as exhaust pipe goop. Alternatively, would doubling up the gasket work here?
 
Good to hear you found it. We may deal with the mysterious exhaust leak in this 2012 AH project. We'll just install the shocks and suspension from 4Wheelonline onto the Wrangler before we can take her in.
 
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