To paste or not to paste....

[blues3]

Decided to whip the exhaust manifolds off to tape them up. Whilst I wouldn't apply paste to the head gaskets, as the joints here appear to be very good, would it be prudent to apply paste to the mainfold to downpipe and downpipe to exhaust system?
The exhaust system joint had to be persuaded to part company with the original downpipes but have been 'resonably' straightened.
Would the fire paste make sure of a good seal?

[mk1fan]

I just renewed the gaskets on the passenger side. Front two sealled fine the back one didn't. Looking at it the manifold's mating face isn't 'square' so undid the bolts and smeared in some assembly paste (I had high temp gasket maker as a second option) before nipping the bolys back up. Let the car idle for a good while to cure the paste before reving it. Seems to have worked for the last 50-miles. S-Club Tour may be too much for it though

[phillpot]

blues3 said:

would it be prudent to apply paste to the mainfold to downpipe and downpipe to exhaust system?
The exhaust system joint had to be persuaded to part company with the original downpipes but have been 'resonably' straightened.
Would the fire paste make sure of a good seal?

No guarantee you'll get a good seal but a light smear can do no harm on mild steel exhaust, stainless may be too smooth and paste will fall off, could try very high temperature silicone sealant. (imho)

I put mine together with copious amounts of "Coppaslip" , helps things slide together and hopefully slide apart when required.

[The Beaver King]

I paste mine.

Tends to seal it right up until my first meeting with a speed bump

[GadgeS3C]

phillpot said:

No guarantee you'll get a good seal but a light smear can do no harm on mild steel exhaust, stainless may be too smooth and paste will fall off, could try very high temperature silicone sealant. (imho)

I put mine together with copious amounts of "Coppaslip" , helps things slide together and hopefully slide apart when required.

I use the coppaslip approach as well.

But when I used a local exhaust place once for a last minute bit of fettling, they smeared the joints with bathroom type silicone - was dubious but it's still there a year on.

Wouldn't recommend it for manifold to head sealing though!

Edit - should have said that was on the 3000M.

[glenrobbo]

The Beaver King said:

I paste mine.

Tends to seal it right up until my first meeting with a speed bump

+1 .... a smear of exhaust assembly paste at the joints ( sparingly of course ) & " Neverseez" on the bolt threads. Works for me.
Just replaced the manifold gaskets after 2 years of graunching on Stockport speedbumps & potholes. They are reputed to be the finest in the land.

Three of the very best speedbumps in the area have been named the Mohne, the Eder, and the Sorpe.
But I think they are too tall for a Lancaster to fly over them. Even my son's Transit Connect scraped its' exhaust trying to traverse these monsters.
And he wasn't even carrying a heavy 'Upkeep' bomb.

Edited by glenrobbo on Monday 2nd June 22:52