Hard time sealing exhaust manifold to exhaust pipe

[Zack]

Hey all,
I'm having a really hard time getting the exhaust down pipe to seal to the exhaust manifold when I clamp them together. I've tried clamping in a bunch of different ways, but nothing is working and I always end up with a sizeable leak.

Are there any tips for getting a leak -free seal here? Is there supposed to be a gasket of some sort because there is nothing on mine except the manifold and the pipe.

[PSL184]

The seal depands on how good and clean the radius is on the manifold. You may have to give it a good clean and file first and then use fire gum when you assemble it all together....

[emmerson]

Support the silencer with a jack, and VERY GENTLY jack it up until the pipe is a good fit on the flange, then smear Firegum on the two halves of the clamp, fit them onto the flange, part tighten the bolts, then turn the clamps to make sure they're seated right, then tighten the bolts.
Easy-peasy.

[PSL184]

Simples !!!

[bmcecosse]

And in another thread somewhere around here are pics of a simple support bracket to take some of the strain off the clamp. It's fair to say - the pipe and manifold must be undamaged - and the clamp must not be stretched out of shape! The jack method works well - make sure the rest of the exhaust system is well supported- but flexible enough so it can move with the engine. Also worth checking engine mounts are ok - and the steady bar is in place and hasn't broken away from the bulkhead!

[Zack]

Also worth checking engine mounts are ok - and the steady bar is in place and hasn't broken away from the bulkhead!

Check and check. Everything seems to be in good condition, except the exhaust pipe where it clamps to the manifold is a bit out of shape and nasty. I took some time to clean the joint well and bend the exhaust pipe back into shape as best I could - It's far from perfect, but better than it was.

Everything went back together easily with a liberal (very liberal) application of firepaste on the joint. Hopefully it will be leak-free when I give it a try tomorrow.

I was previously assembling the joint dry, so hopefully the firepaste is the piece that was missing from the puzzle.

[Peetee]

On the last car I had I just couldn't get a good joint until I removed the manifold. the mating face and shoulder (the other face that the clamp attatches to) had an uneven layer of deposit that had discoloured in a similar way to the manifold and 'fooled' me into thinking it was part of the casting.

[leyther8008]

I only got a good seal using an original 'cast' clamp I found those wriggly tin ones to be a waste of time, one of the mini specialists on fleabay sells them but they are a bit dear like £10 but I reckon I saved that on fire gum over a year.

[paulhumphries]

I had similar problem with my A35. In the end I changed the manifold and used a cast clamp - only to find the engine would hardly run !
Turned out to be partially blocked exhaust was causing excessive backpressure and hence the constant leaks. The replacment manifold, although sealed, then simply smothered the engine.

Paul H.

[simmitc]

A trick published in Technical Tips is to use a piece of coppr wire wrapped round just underneath the flange on the pipe, and then do the clamp up as usual. Works every time.

[bmcecosse]

Not heard that one before - but not needed it either!

[Zack]

The firepaste did the trick!

Hopefully it will last for more than just a couple months.

Thanks for all the advice!

[rayofleamington]

Works every time.

not quite every time

[Cam]

Hopefully it will be ok now but in the past if the 'bell' is distorted then I have had to remove the exhaust and re-form it by placing it over an upturned spare manifold held in the vice and hammering the 'bell' into shape to correctly match the manifold. Hopefull you won't have to do this and all will be well now.