I have a terrible rattle at certain revs (currently 2700-3000) that has come back again after mysteriously going away. When it stopped first time around, I thought something had dropped off, but it has come back since swapping my SS backbox for the original (selling the car). It is in the area of the downpipe, but despite having it on the ramps at KwikFit, I can't locate the source (and it doesn't appear to be a loose heatshield). I am quite sure it is something loose, but what, I don't know. Has anyone ever heard of the front cat breaking down and rattling....?

Please help. In desperation,
Zip

 

Zip

I had a similar problem at the same revs as you described. As a technical pleb you'll have to bear with me, but mine was a broken exhaust shield. This shield is accessable from the front of the car, just back a bit underneath the bumper. These little shields (one each side) are held on by 3 bolts. One of the lugs on the shield had snapped, causing the shield to rattle - bags of spanners stylee - put the ***** up me!
I think this is different from the heatshield you mentioned, I'm sure someone else can clarify.

Hope this is of use

Justin

 

Cheers Justin,
Although it had been sorted a couple of times, indeed one of the lugs had completely sheared, so I have removed it completely (had to cut it off around the lamda sensor without damaging it).

Lets hope its new owner doesn't park in any fields of dry grass...
Z

 

Its either heat shields (check the one around the pipe that comes up to feed the turbo and the upper and lower turbo heatshields) or it is indeed a cat.

I have seen a few cat failures, including one on a 22B with 1200 miles on it, but these are rare. If the cat has failed, bits of burnt cat brick will work their way along the entire exhaust system, so its easy to diagnose