Exhaust Bolts Problem

I've been trying to replace the three bolts that hold the flange from the headers to the CAT. The first bolt came out without too much problem with a bit of help with a Hammer and punch. Then it got more difficult the second bolt was just a rusted blob so no chance of undoing it so ground off both ends. I then tried to drill through the remains of the bolt with a HSS drill bit and some from a Dewalt kit but I just couldn't get through it. So any suggestions on how to remove these bolts as I've 5 more of them to get through?

Heat and a good whack.

Buy new HSS drill bits and use any old oil or WD40 to lube the end of the bit as you drill in order to prevent them from going blunt. It's not critical to get it exactly centered, but it's preferable. In the picture you have one that is partly drilled with a smaller drill bit - that's fine, keep going, and once you're through, revert to a decent plumbing blowtorch and a punch and a hammer to get the remains out. I've done this job myself, and it was a continuous cycle of what I described above. Lube your bits literally every 10 seconds of drillling. :thumbs:

Also, adding any sort of lubricant keeps the bolt from getting too hot and hardening.

Remove the cats from the car - looks like they're still attached here? Then centre punch, low speed and medium pressure + lube as suggested here.

The drilling is going to be the biggest pain, I managed to avoid it with heat/bigger punch/bigger hammer. When I say hammer I mean mallet, the biggest I could find but still swing with one hand as I was getting nowhere with just a regular hammer. It came apart quickly in the end.

Heat is what you need and lots of it .. at work we use oxy acetylene and even then they wont shift without a decent hammer / punch .. The bigger the hammer and punch the better . 997 are far easier but that's cause they are made out of chocolate !

Hi I did exactly this job this week on a 130k mile Boxster. Bolts with no remaining head or nut one side, looked like they had never been there. Other side just very very rusty. IMHO forget drilling. On mine I was paranoid about hammering too hard on the remains of the bolts because I did not want to damage the manifold bolts which are also corroded to fk. I know what its like to lay on my back and drill out broken manifold studs because I did it on my 993. Never again. So one side with a junior hacksaw I sawed away at the join where the exhaust gasket is. It doesnt take much metal off the flange and it doesn't matter anyways because the seal is in the middle. You can quite quickly reach the bolt, but its much tougher from there on in. Once you have two bolts sawn through then just rotate the still tight exhaust and the top bolt will start to loosen. Then it will pull out. The other side I heated until cherry red and punched the two lower remains of the bolts out towards the back of the car. Then rotate the exhaust back and forth until the top stud loosens and pulls out. Anything still stuck in the holes once the exhaust is free can be dealt with by heat and or a joint splitter. Best of luck, its pretty hard work. Berni

Thanks the sawing bolt in half idea sounds good might give that a try. As to the drilling the world seems split into two...those lucky few who say went through like butter and then the rest of us sweating and swearing lot. Anyone have any recommendations for heat sources that aren't too expensive? Unfortunately I fall completely outside any Government help so no chance of any money for a good while yet.

After going through a succession of crappy cheap torches costing about £25 from B&q I bought a Bernzomatic from Screwfix. It's been absolutely brilliant, works in any orientation and after three years of odd jobs and plumbing it still is about 1/3 full.

Rothenberger Super Fire 2 Torch & Mapp gas

I've never used a torch like this.....how hard is it to keep the heat in the right place and not go melting anything delicate under the car?

Hi I don't think there is anything too close to the exhaust flange, just be sensible! You could always use some strategically placed tinfoil if you are worried. All the best Berni