Exhaust leak---help...

[Cody]

93 4.0 ZJ.

It has aftermarket headers on it. No cracks visible. Replaced the exhaust manifold gasket, and the donut gasket that connects the headers to the exhaust manifold. Still leaks.

WTF? Ideas?

Cody

 

[Brett]

Gibson header, FYI

 

[Brett]

This!

 

[I Lean]

Where's the leak from? Where the header meets the head?

Since there's a new gasket on there, pull the header back off and look for leaks--you should be able to see carbon if there are gases escaping somewhere.

I've fixed a chronic header leak on an AMC 304, the problem ended up being that the small raised areas on the header designed to "bite" into the gasket were too small, and didn't actually squish the gasket against the head. (they pressed into the port instead) It was solved by welding additional material onto the header, then grinding it down even with the factory raised lip--basically making that wider.

So, where's yours leaking from?

 

[Ken]

Just did this on mine. If you aren't finding any leaks check your fuel pressure next.

 

[Caleb]

Just did this on mine. If you aren't finding any leaks check your fuel pressure next.

it's usually pretty easy to tell if it's an exhaust leak, and the fuel pressure wont have anything to do with the sound of an exhaust leak...

 

[Cody]

Ya, I'm not sure how fuel pressure issues can sound like an exhaust leak...

 

[Brett]

Where's the leak from? Where the header meets the head?

Since there's a new gasket on there, pull the header back off and look for leaks--you should be able to see carbon if there are gases escaping somewhere.

I've fixed a chronic header leak on an AMC 304, the problem ended up being that the small raised areas on the header designed to "bite" into the gasket were too small, and didn't actually squish the gasket against the head. (they pressed into the port instead) It was solved by welding additional material onto the header, then grinding it down even with the factory raised lip--basically making that wider.

So, where's yours leaking from?

You know how long it took me to pull everything off to just get to the header?

It "sounds" like it's just a single port leaking. I did file the head smooth so that the gasket would mount flush. There weren't really any high spots on it that I noticed. Honestly, it sounds as though it might be cracked, since it's just a single puff puff puff. As far as I knew, when I got this header for Jon two years ago, the Gibsons were not prone to cracking. Oh well. Might have to just yank it out and check it over, since I didn't look it over when I replaced the exhaust gasket.

 

[78mitsu]

I've tested headers for leaks before kind of like you test a tire for leaks, put tape across the head flange get it tight and clean it good first then put it in water then apply a small pressure to it (it'll take a rag and an air compressor turned most of the way down. it'll bubble. you can also take a mapp torch and pass it along the welds, it should glow if it's cracked.

 

[jeepin4x4james]

Did you use the Copper spray on gasket sealer? That fixed it on my buddies 95 YJ.....He had aftermarket header as well

 

[Brett]

Did you use the Copper spray on gasket sealer? That fixed it on my buddies 95 YJ.....He had aftermarket header as well

No, I didn't use that. I didn't even think about that....might have to pull it apart and see what happens.