Cat to header bolts

Right, tomorrows project is my rusty nuts! , I have nice new Design911 quick release tail clamps, so will be dremeling the old clamps off for a polish which should be straightforward. Looking at my muffler to cat sleeves, those nuts & bolts are pretty rusty too so thought I'd replace those before it gives me a problem. The worst bit is the cat to header triangular plate bolts...there are no nuts! They've rusted away to molten blobs on some and just rusty bolts on others, to be honest I'm not sure how it's holding together but there's no blowing or leaks at all. It looks like they're fixed bolts from the cats as there is no hex head on the cat side, so to sort this it's either new cats, which seems crazy whilst they're fine, dremel off & drill out the bolts or else leave the hell alone until they blow!! If I drill them out I run the risk of creating a leak :? Any advice Don't even want to think about manifold bolts but they don't look that horrific at the moment!

Dremeling the tail pipe clamps off wasn't as easy as I was expecting! Must have got through 20 cutting wheels, very solid and with the nuts and bolts just a corroded mess & lack of space it was very tricky & very dirty! New clamps on are much better, designtek from design911. Pipes now all clean and polished cats derusted and high temp sprayed silver, all looking much smarter.

Hi I have been there on a 993 so I know how you feel. I would take a look at the header to engine nuts. If they get too far gone they can be a total mare to replace. Berni

Having recently taken a cat off.... Cat to silencer clamps, get a heavy angle grinder and take off where the nut meets the clamp. New nut and bolt sets are available at halfords for a pound odd. For the car to header triangular, tried for hours with a dremel, but poor access, then i tried just a junior hacksaw on the blobs with a new blade and was through in less than 5 mins per bolt... cut saw flush with the header side. do it from below easy. |Then wiggle the cat or put a wedge in the gap and it will start to come away, the bolts will stay in the cat and you can just knock them out when off the car. It looks so much better with new bolts.

That's great advice, thanks. Do you have to take the cats off to get the bolts out of the triangle plate? Will a whack with a drift knock them through? As they're not blowing, am I best to leave them until they do?[/b]

due to access you are very unlikely to knock the bolts out, as the cat just wiggles off, take it off to replace the bolts as they are likely to be rusted into the car side of the flange,

These 3 nuts per flange do rust away to nothing as described and if you give the throttle pedal a bit too much `gas`,on start up especially, the pressure can blow the gasket and set off the engine management warning light which obviously costs £££ to turn off. the stud is fixed in the manifold and the nuts clamp the `cat` flange to it.

Hi If you are going to replace the header nuts you might consider using copper coated steel ones. I am not sure about the 996, but on the 993 they are hard to get at so I replaced the standard 13mm ones with the special copper coated 12mm's. All the best....Berni