Exhaust to manifold joint leaks

[AdamWilkes]

Is there a secret for sealing the exhaust-to-manifold joint ?
I just cannot find a way to keep the seal, well, sealed. To this end I have recently fitted a new exhaust pipe section, and have tried two different exhaust pastes to help seal the joint. I'm unsure whether the clamp is distorted (I tried taking up any clamp stretch by packing out the clamping flange-area with a 3mm wire ring as well, to no avail), or whether the two mating surfaces need a special sealing paste or washer, or if my manifold is scrap, or, or...
The manifold mating surface look good and smooth(ish), the (new) pipe seems tight and immovable against the manifold. When first sealed with paste all seems well, but a few miles down the road the chuffing sound starts - I guess the paste has been doing all the work and then it gets blown out (previously left to dry overnight).
Any experience of this ?

 

[Paul Narramore]

Adam
A similar thing would happen to my 2CVs as with age the cheap and cheerful exhaust clamps couldn't do their job for long. The solution was to buy special cast bronze exhaust clamps (from ECAS) which really worked.

 

[André4Renaults]

Likewise with my Citroen. I bought an expensive exhaust system and fitted it myself, since when I've had no problems at all. It's a case of the price you pay vs. the quality you get.

 

[AdamWilkes]

I have found no manifold-exhaust pipe clamps on Der Franzose, Melun Retro Passion, via a Google search or on Ebay, even if that's the problem
The leaking problem arose soon after re-mounting the manifold (machining of the head-mating surface) and using the original exhaust, I wondered if the original exhaust was past it... the replacement piece has been no different. The various exhaust sections have been disassembled and all joints re-made to settle comfortably.

I suspect that the 2CV pipe would be even tinier that the R4 pipe, so that clamp may not be usable for the R4.

Would a 'normal' two-piece squeeze-together-with-a-V-channel type of clamp work there (I think that the stud casting sticky-out-bits may foul the all-round hugging shape of the clamp) ? I have an angle-grinder....

Do any other R4 manifolds ditch the use of studs to clamp to the exhaust?

 

[reidalpine]

Adam-make sure the pipe is "free-floating" not bindig in any direction before clamping together
when locking it up use slight taps with a hammer to make sure it's not binding in any direction.
Using exhaust-paste has no effect as there will always be Some movement in the joint anyway
These clamps comes in various quality so go for the heftiest one you can find. -Reid.

 

[harbourseal]

I use holts Fire gum.
It is like tooth paste when you apply it to the joint on the manifold
After firing up the engine it hardens and makes a good seal.
I use the studded connection that is standard to the 1108cc Cleon engines.
The free floating connection that Reid mentioned is together with the fire gum works for me.

 

[AdamWilkes]

Thanks chaps, lots of good advice! I've no idea where to look for a better exhaust clamp (if needed), though may modify the existing one to strengthen it first. I know that it has stretched to an oval hole.
I do have a welder as well !

I shall break out the tapping hammer for the next re-fitting!

Just to add to the mix, the little darlin' failed to start yesterday (coughing and stopping), and I have yet to find why.... feels like fuel jet block to me, but as has been said (Malcolm ?), 80% of all fuel problems are electrical. Yet to be proven!

 

[AdamWilkes]

Update: just proven myself wrong/right - my (above) fuel problem was a failed condenser. So, electrical after all

Moral: thinking about things by writing/typing them down is useful !