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Bolts cat to heat exchanger


New member
6 Sep 2011
Anyone had trouble trying to get these undone? 12mm socket won't fit completely over it- only sits half way over bolt head- I've cleaned the heads with a dremel- but still won't let the socket sit flush-


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They were 13mm on mine. If you can't get good purchase on them with sockets or spanners I'd use a dremel or nut splitter on the nuts and the bolts can easily be persuaded out.

I replaced mine with stainless nuts and bolts (with some copper grease) and have never had a problem taking them apart since.

I had mine replaced before I exported my car from Q8. The car was 15 years old then and they had to be cut off. I stupidly told my Indy to buy from Porsche, silly price but thought they would be better :wack: they were just steel bolts :oops: Stainless steel seems a good route to go. However, mine were greased up with copper slip and having had the boxes and CAT off a couple of times since have never had a problem with removal.

ATB :)
As above, don't fight them, just cut them off and order A4 stainless from Accu or some other supplier. HT grease as well, you'll appreciate doing it, especially if you do your own servicing etc
Thanks for the reply's- I think they have rusted down from a 13mm to a 12mm apart from the last few mm next to joint- I'm going to get a nut splitter- someone said the nuts are captive but can be levered out of joint?.
Can't believe how rusty the fasteners are- and the heat shields around the cat - well biodegradable- must have sprinkled rusty dust for years lol
Only one captive nut if memory serves me right. :thumb:

ATB :)


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Is that really a welded captive nut- or the same as the other two that can be prised out?
I'm going to cut the bolt heads off and knock the bolt through

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