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RTV Sealant
Ferrino - 26/1/07 at 02:13 PM

I need to apply some high-temp RTV sealant to the 4-2 join on my stainless exhaust manifold, as I get a slight leak which I'd like to sort out. I've tried it before and it has blown out within miles as I wasn't very thorough when cleaning off the carbon deposits on the pipes and may have not let it cure for long enough. I now want to do it properly!

I was told to bring the surfaces back to a shiny finish with something like Scotchbrite, so will do this. But how about the curing process - is it too cold for it to cure properly with the current weather (ie. nothing close to room-temp in the garage)? Or could I just stick a heater in there for a while.

Thanks, I know this sounds a bit petty but it's something I want to get right as it's a bit of a pain to disassemble the manifold every time I try to seal it up.

macnab - 26/1/07 at 02:30 PM

I use gun gum, fab stuff just don't use alot as it expands

bbwales - 26/1/07 at 02:35 PM

Hi,
I have found fire gum to work very well. We used to use it on the Jag engines in the CVR(T) range of tanks on their exhausts

Bob

jimgiblett - 26/1/07 at 03:26 PM

I wouldnt bother with RTV as the pigments tend to be chalk based and dont like heat much. Use a good quality "Clear" silicone sealant eg. Unibond.

- Jim

Ferrino - 26/1/07 at 04:02 PM

Thanks guys - definitely won't be using that fire/gun-gum stuff as it was nearly impossible to disassemble my old manifold with that! I have already bought some high-temp RTV (rated to 350 degrees C) so will give that a go for now.

BTW, where can I buy Scotchbrite?!?

RazMan - 26/1/07 at 04:46 PM

quote:
Originally posted by Ferrino
BTW, where can I buy Scotchbrite?!?


The kitchen section in the supermarket - it is the green scratchy stuff used for scouring pots

Confused but excited. - 26/1/07 at 05:33 PM

You could always warm you pipes up with a hair dryer.

rusty nuts - 26/1/07 at 07:32 PM

Might be better to make sure the manifold gasket surface is flat . Had the same problem with mine and after the third attempt to seal it I took the manifold off and cut the mounting plate so that each pipe was seperated .Have had no problems with leaks since

britishtrident - 27/1/07 at 04:40 PM

quote:
Originally posted by Ferrino
Thanks guys - definitely won't be using that fire/gun-gum stuff as it was nearly impossible to disassemble my old manifold with that! I have already bought some high-temp RTV (rated to 350 degrees C) so will give that a go for now.

BTW, where can I buy Scotchbrite?!?


RTV sealers just aren't suitable for the area

Firegum standard motor trade practice for sealing exhaust joints it dosen't cause any problems dismantling.

Gum-gum is even less of problem but is intended for big holes..

Ferrino - 27/1/07 at 05:31 PM

That's odd because one of the intended applications of the RTV product I have is for the sealing of exhaust manifolds and has been highly recommended - will let you know how I get on! I definitely used GunGum on my last manifold and it was just a pig to get off!

RazMan - 27/1/07 at 06:06 PM

I was told that RTV is used a lot by the racer boys - it allows easy disassembly but still seals well enough to be effective.

[Edited on 27-1-07 by RazMan]