Exhaust / cat

[scott]

I have had my cat welded today as the flange had almost completely split all the way around, (where it connects to the exhaust), it was starting to sound like a tank!
The clamp is also bent, quite rusty and one of the studs is stripped, the lad who welded it for me managed to get it back on good but he recommended i buy a new clamp, which i was going to anyway.
It still sound like it has a very slight leak but it is 95% better than it was .

Just one question, is there supposed to be some sort of gasket between the cat and exhaust, NOT the manifold side, the exhaust side. Its just the lad who did it for me said there is normally some sort of gasket so when the clamp is tightened up it seals the join between the two sections.

 

[ste1985]

hi m8. ive had a cat problem not long back. mine does not have any kind of gasket between the exhaust and cat, the cat should just sit inside the exhaust an the clap should pull the two in together. hope this helps.

 

[scott]

hi m8. ive had a cat problem not long back. mine does not have any kind of gasket between the exhaust and cat, the cat should just sit inside the exhaust an the clap should pull the two in together. hope this helps.

Thats what i thought but when the exhaust and cat are in position there is a slight gap, 1 or 2mm, like you said the clamp pulls them together, hopefully when i get the new clamp on it will sort it.
Seems a bit shit that the cat split anyway, it was replaced under warranty by the previous owner, probably due to the stealers fitting a crap clamp back on, putting the clamp on twisted or overtightened.

 

[scott]

Just fitted the new clamp and it now sounds better than it did when i bought the car, no leak at all.
It did take me two attempts though as the first time i didnt realise the cat and exhaust were hanging down slightly so the clamp went to twisted. Loosened it off and pushed both cat and exhaust up slightly and tightened back up, spot on.

 

[PPTom]

No gasket as standard, but I always use high temp silicone in this joint to help with a seal. Its a very common place for an exhaust leak. The bracket deforms to fit when its done up, so a new one should be fitted every time one is taken off. I usually use the jack on the cat, simply to take its weight and hold it in position, while I'm concentrating on getting the joint nicely lined up, I think its one of those jobs where you could use another set of hands, one to hold everything in place, and another to do up the clamp.
A tip to check for leaks is to get underneath the car, engine running, while a mate puts his hands over both tail pipes, stopping the gasses from escaping. if the joint is still leaking you should hear a hiss. Another one is to look at the joint after the engine has been running from cold for 30sec - 1 min, if there is any gaps then you will get a drop of water on the joint that has seeped out from inside the exhaust (condensation)

 

[scott]

Just a quick update..
I recently purchased new exhaust hangers as the old ones looked a bit rough. On replacing them i found the exaust now sits approx 2inch higher at the cat end. When i compared the old center section hanger rubber against the new one i found the old one was streched about 1inch, and that was without the weight of the exhaust on it so its hardly supprising the cat had split as the exaust was hanging down loads.

Probably worth replacing weather you exhaust is blowing or not .