Silicone to seal exhausts

[Concrete-crusher]

Hi I have bought a shiny new exhaust system and when asking about sealing the joints was advised to use silicone.

This was a surprise as I work for a silicone manufacture and had not heard of its use in the motor trade for exhausts.

The garage showed me a product that was rated upto 240 deg c , now I know silicone will withstand that as my company manufacture silicone that's rated upto 300 deg c so my question is how hot do manifolds get just after the gases leave the head ?

Thanks steve
S4 ish

[delle]

As far as I know, the temperature at the manifold is 600+ deg C

Delle

[john.p.clegg]

I use silicone on a regular basis after being told the same,does a good job of slipping the pipes together and sealing....also O.K. when it comes time to dismantle...

Go for it...

John

[Grizzly]

I've seen all sorts used to assemble slide over joints in exhausts, the trick is to have a reasonable fit to start with then the paste helps the joint slip over but dries quickly so the exhaust pressure won't push it back off the first time it fires, it also has enough about it to block off gaps sufficiently until the carbon finishes the job on the inside. For me i'd only use assembly paste on Slip joints.

I was always led to believe you shouldn't seal the gaskets on Manifolds for example, if there is a leak its often because the flange is warped and from experience with Turbo cars the flatness of the two mating surfaces are the key.

[rgh0]

You can use silicone on the join to the head as it is cooled by the head itself and does not get that hot. The Y piece joins generally run to hot for even the hi temp silicone and it burns off and the join then tends to leak. The last join to the rear muffler is normally cool enough again to use silicone I have found.

cheers
Rohan

[john.p.clegg]

Off topic..

Delle
Looks like you could do with your carbs balancing

John

P.S. yes I know it's efi.

[englishmaninwales]

I use Permatex Ultra Copper High Temperature Silicone RTV on collector joints and seems to work well and keep it all gas tight, but as above starting with good fitting pipes.
Malcolm