exhaust sealant

[n james]

can anyone advise on a sealant to go between the primaries and the cat, iget a lot of back firing

at steady revs for db testing which just pushes me over the limit, also mot coming up, and i know from experience that the air sucked in can mess up the lambda readings.any help appreciated.

[Peter T]

I found this a problem on mine and tried numerous sealants which all seemed to fail as teh gaps were too big.

In the end i used an exhaust expander to get a perfect fit of the primaries into the collector and no sealant was needed. Cured the problem no end.

[Nifty]

I was told that RTV sealant would do the job .. providing the gap isn't a cavern obviously.

 

Keep off the straight and narrow 😬

[shn7]

Nick,

 

I've used Wynn's Instant Gasket (or Gasket Maker). Rated to 300C for short periods and seems to last well in my car. As said above though it will depend upon the gaps to be filled.

 

Steve.

Sussex (West) AR

Not forgetting Percy the Polar Bear

[Stationary M25 Traveller]

Lots of posts on this a few months ago - a quick search will tell all. I used a light smear of bog-standard clear silicone sealant, which did the job a treat.

 

7 related photos

[6speedmanual]

ENVIROGRAF fireproof silicone sealant. (clear)

 

Withstands and remains flexible at 1200 deg C

 

I have successfully used this to stop a blow from a cracked exhaust manifold (not on a 7) by simply spreading a bead of the sealant over the crack and smearing it into the crack. I never thought it would work, but it did!

 

On the 7 exhaust collector, the sealant can be applied after assembly. Smear the sealant into any gaps between the primaries and the collector. Wipe off excess.

 

The only problem here is the inner parts of the pipes within 4 tubes of the collector are rather inaccessible so neat job is tricky. An ice lolly stick can help.

 

The pops/bangs in the exhaust do seem to be exascerbated by having air leaks at the collector, however I doubt enough air would flow backwards up the exhaust to upset lambda readings.

 

 

6SpeedManual

*tongue*There's no such thing as too much BHP per Ton 😬

[n james]

thanks all,

i think i might try this envirogras,ive never heard of it, where can i get it from?

[Sheds Moderator]

If the gaps are too big then cut up a beer can and use it as shimming material in the joint.

[millsn]

I would avoid sealant. That day you try to remove the collector you will rue that you used it. Are you sure that your mixture is ok?

[shn7]

millsn,

 

The sealant I've used is fine when dismantling. Just slides off easily but had remained sealed.

 

Steve.

Sussex (West) AR

Not forgetting Percy the Polar Bear

[n james]

yes the mixture is good, its just been mapped by ministers, thanks