I have this job to look forward to tomorrow. The bolt part is built into the cat, so i cant just grind it off and the nuts have been heat treated so many times that they might aswell be made of cheese. Any hints and tips for making my life easier?

get some “plus gas” or “3 in 1 high penetrant” spray …. i dont mean GT85 or WD40 …..

get that on it today

no way you can grind the nut off the flange and use another nut to secure it in future ? – normally i see these they are flanged with a nut tack welded or built into the face of the flange.

failing that – what are you replacing ? the front pipe ? or the rear pipe ?

or the lot ? if its the lot id just cut it infront of the cat and behind the cat with tthe grinder and work on the bench to get it free – much easier than upside down on the street on a high kerb 😉

Everything other than the cat. Dont want to remove the cat as that would bring with it a whole other world of hurt.

I’ll have the car on axle stands, or ramps if I can get hold of some.

Is there room to get a nut splitter onto the nuts? As you say, they will be soft, so should split easily and not damage the bolt.

I had this problem once. Had to grind off then get a garage to oxy torch and press out the remainder of the stud.

Right – I’ve got the car up on ramps now and I can see better. I am not convinced that the nuts are meant to turn – they look more like they are attached to the front pipe flange. But, there is no bolt head on the other end of the threads if any of that makes sense.

Any ideas?

wire brush

cold chisel

mell

cold chisel

[video]http://www.youtube.com/watch?feature=player_detailpage&v=VrXSZzqvDfM[/video]

your joke is lost – im on a satelite connection in the middle of the turkmen oilfields.

Cold Chisel – 80s Aussie rock band

OP, makes no sense, if it is a threaded fastener, something must turn to assemble system.
If they are captive nuts then the bolt will turn. If it’s a stud on cat, then nut will turn.
Nut splitter seems best suggestion.
I hate old exhaust systems I would biet the bullet and get garage, with windy gun/gas axe, to put new system on.

Gave up on trying to get the nuts off. Just replaced the middle and back boxes which still took a lot of cutting, griding and swearing.

Will just hope that my bodged repair is adequate for MOT. If not, I’ll take the cat off and take it to bits on off the car.