[Noob] Swapping Cat / Crp

[ankh]

All,

 

I've been running with a CRP for years, but swapped the cat back in for the MOT in Feb. Things just aren't the same with the cat in place, so wanted to try the CRP again, especially as summer looms.

 

So, rather than paying someone to do it, I though I'd give it a go myself. I've still got the CRP, but as a mechanical noob wanted to check what appeared to be a simple job...

 

AFAIK, I can just unbolt the cat (have soaked the bolts in oil overnight and they're compliant) and swap in the CRP, but I had a few(!) questions :

 

* I'm not mechanical - I used to swap out the bearings in the crank of my push bike, but that's the extent to my experiance, from 25 years ago... Is it a simple job?

 

* I *think* the original cat had built-in bolts on one side, so I guess I need to buy a set of bolts in order to secure the CRP to either the silencer or the manifold.

 

* The post-cat sensor is in-place on the cat and I assme it was on the CRP, since there's a threaded place for it. I know when I had the CRP fitted there was something done to avoid the post-cat sensor firing, but don't know what!

 

* Do I need to replace the gaskets buffering the silencer / manifold?

 

I think that's it, unless I've forgotten anything. I'm gonna have a go next weekend, so any input appreciated!

 

Cheers,

 

Rich

[M@r]{]

I'm a complete numpty when it comes to mechanics, but even I've swapped an exhaust/cat. Any sensor deletion or MIL light issues will have been sorted when you had the CRP fitted previously (assuming you had no light on the dash. Its likely the solution is still in place (a resistor placed somewhere I believe)

 

The times I've swapped stuff around I haven't bothered with new gaskets, just used the same ones again. May be worth while having some to hand or some instant gasket, just in case you gaskets fall apart when you remove the cat. And have a wire brush to hand, to clean up the surfaces where they meet.

 

One good tip, have an electric screwdriver of similar handy, all those 8mm bolts to remove the undertray are a PITA and they are long and the thread fine, takes ages to undo them not to mention the aching wrists afterwards

[stockhome]

I would replace the gaskets myself as they are pence, mine which is the same as yours and is 6 bolts.

 

I put a little copper grease (especially if you are using stainless bolts) to help with removal next time and tighten to about 45nm

[John FISH Curtis]

I can swap a CAT/De-Cat in about 20mins.

 

Remove undertray

Remove the 6x bolts (You need 2x 17mm spanners/sockets/short breaker bar)

Remove CAT

Offer up de-cat with 1x gasket and hold with 3x bolts

Slide gasket into other side and hold up with bolts

Fit all nuts and tighten

Stat car and check for blowing

Re-fit undertray

 

 

On my S1 I dont need to jack the car up.

I would grease the undertray bolts when re-fitting

Buy a new set of gaskets

If the bolts on the CAT are solid, drench in WD40, leave for 12hrs and re-spray

[ankh]

Thanks to everyone who posted.

 

I've successfully swapped out my cat and the car sounds great again!

 

Only problems were with me forgetting to refasten where the 'arm' of the cat is held via a rubber mount and the CAT sensor cable getting twisted when tightened, meaning I had to pre-twist the other way so it came out evens when it was tightened in-place!

 

Now for the testing in the tunnels of Mont Blanc:D