Exhaust replacement

I'm an idiot. The B had an MOT advisory for a slight exhaust leak at the back box. It was right on the seam and whilst it might have been repairable I figured that if it had broken through there then there would soon be similar holes appearing elsewhere.

Time for a new exhaust - this one had lasted about 10 years which doesn't seem terrible for a mild steel one. So I ordered a new one from the club (prices had jumped somewhat in the intervening years) and whereas last time I installed it with just the factory coating, this time I thought I'd try protecting it a bit more.

I looked at various Very High Temperature (VHT) paints and settled on a clear coat which I hoped might preserve the bare steel finish. We'll see how this lasts, I might end up grabbing a couple of cans of a solid colour if the rust starts to appear.

So then off with the exhaust. As I had used traditional U-clamps and exhaust paste last time there was no way this 3-piece exhaust was coming apart. Once off the car I cut it up into manageable lengths for disposal and to have a bit more of a look at how bad it was internally. I should have just had it welded, I'm an idiot. The cuts through the pipes revealed bright steel just below the outer rust and looking through the various sections showed none of the glasspack had failed - all the pipes and internals were clear.

Ok, so no going back anyway now this one was off and the new one was prepped.

Of course when taking off the old exhaust I'd ended up with two of the exhaust manifold studs shearing off. Last time this happened I found a local engineering shop and had them drill out and retap for new studs. This time I'd just seen a video where John Twist had drilled and retapped a manifold himself by using the old exhaust's clamp plates as a guide. So I ordered a helicoil set and set to drilling out the studs.

It looked ok and the helicoils worked well, but when it came to test fit the exhaust it was a bit of a tight fit. When bolted up it was clear there was a slight leak at one of the donuts. I'm an idiot and should have just gone to the engineering shop where they could have ensured the studs were drilled out perfectly straight. Clearly mine had a marginal angle to it.

Now I could have gone and found the proper engineers but I had a feeling I would get tutted at and I wasn't feeling up to that, so I sourced another exhaust manifold and fitted that. That will allow me to track down an engineering shop to fix my mistake as I have a feeling it might be a bit more complex now than just redrilling.

Back to the exhaust proper. All this have been side-stepped by having an exhaust which could have been pulled apart in sections allowing me to just replace the back box. So I wanted to avoid the traditional clamps which distort the pipes and also avoid using exhaust paste. In order to give me the best chance of getting this thing apart again in the future I went for some Mikalor clamps (47-51mm) which create even pressure around the pipe.

I was hoping this would be sufficient, and it almost was. Once everything was slotted together and clamped up I had very slight leaks at each of the joints. Rather than use exhaust paste which would cement the pipes together I pulled the joints apart and used plenty of copper grease. That both sealed the leaks and will hopefully keep the sections from welding themselves together.