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How To:- Fit a New Exhaust (Mongoose)

I put this article together as I was doing my own exhaust and could not find a step by step guide already posted. Perhaps this may help someone in the future.

Jack up and support the car either on axle stands or ramps if you have them. I chose to use the rear cross member as the support for the axle stands as I don't like using the sill points. Just my preference until I get around to making some blocks so that the sill seams don't get damaged.

Don't forget to chock the front wheels.


Looking at the Cat joining flanges where they connect to the back box and the B-pipe it became clear just how corroded the bolts and nuts were see pics below. The only way to remove them was to cut them off.




Using an angle grinder and cutting disk I cut off the lower bolt at each end of the Cat as these were very easy to get to. I also cut off the lower bolt of the two that secure the back box to the B-pipe Cat flange. The top one of this bracket I had to cut using a hacksaw, as I couldn't get access with the grinder. (See pic)



Now I came across the next problem, how to get at the top bolts either end. I decided that I needed to get the back box out of the way first, and as I wasn't intending to use it again it didn't matter if I destroyed it getting it out. If this hadn't been the case the only way to get my top bolts out would have been to use oxy-acetylene to cut them out which I don't have access to at home. As you can see in the picture below, I used the cutting disk and a cold chisel to cut the exhaust pipe. I did this back box side of the Cat flange as this was the only way I could get the box out without damaging the Cat, whatever you do don't cut it B-pipe end, (I know it seems obvious but it needs saying).



This allowed me to undo the back box mounting bolts see above and below, then drop the complete back box away.




This left the cat still connected by one bolt to the B-pipe flange, but now with the back box out of the way it was easy to get the grinder in to remove the remaining bolt and drop the Cat away. The Cat I am saving to put back in for my next MOT, looked inside it and it was very clean and I was able to see straight through the matrix so not bad for something 12 1/2 years old.



Using 2 new bolts, washers and nuts, a new exhaust flange gasket (sourced from local exhaust suppliers for 99p each) and exhaust paste I fitted the De-cat pipe to the B-pipe with the bolts just nipped up initially.



The next thing I did is optional; I bent the rear grill up out of the way to become a member of the Church of the Folded Grill as I believe if its shiny it needs to be seen lol.

Next smear some exhaust paste on the mating surfaces of the De-cat and back box flanges and fit another of the exhaust flange gaskets (I don't know why they call them gaskets as they are more like a copper ring than a gasket). When installing the back box I found it easier to attach the driver side mount first leaving the passenger side leaning on the ground, see below.




All I had to do then was swing the passenger side up and secure loosely in it's mounting with bolt and nut. Next fit 2 new bolts and nuts to the De-cat/back box flange and tighten up fully. Then tighten fully the 2 bolts at the B-pipe end of the De-cat.
Lastly tighten the exhaust mounting bolts passenger side and driver side then stand back and admire the new look.




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