RTV on exhaust manifold gaskets?

"NaturallyAspirated" (NaturallyAspirated) 01/02/2015 at 13:42 • Filed to: Exhaust leaks

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I've been having a terrible time getting the exhaust manifold on my Subaru to stop leaking from where it bolts up to the heads. I think the manifold got tweaked a little at some point, and since it's a big one-piece deal, one side or the other doesn't seal up perfectly against the heads. The OE Subaru gaskets are a lot thicker than Fel-Pro et al, but they still leak a little.

I was watching an older episode of Mighty Car Mods, and at 6:00 you can see a tech putting what looks like Permatex Ultra Grey onto an exhaust gasket. I'd never thought of putting RTV on the exhaust manifold gaskets before, and I'm thinking of trying it this weekend. The only downside I can think of is that it'll be a real pain to get the exhaust manifold off the next time I need to.

Any thoughts, Oppo?

Funktheduck > NaturallyAspirated 01/02/2015 at 13:47

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I see no problem. The sealant should fill in the gap where the gasket is leaking. That or you could try to grind it flat again.

RamblinRover Luxury-Yacht > NaturallyAspirated 01/02/2015 at 14:12

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This is Wurth Silicone Special 250. 250 in this case meaning it's good for 250C/482F. Exhaust temps are not uncommonly hundreds of degrees higher than that, with >1000F being pretty common. Is he a fucking moron? Yes. Yes, he is.

sketchcat > RamblinRover Luxury-Yacht 01/02/2015 at 15:44

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yep.

"..lets squirt some goo in here that will maintain a couple thousandths gap between the two parts and eventually burn away."