I think mine has been de catted....where are they?

[silverback mike]

now I've had my metallic clonk looked at, it turns out to be the stainless exhaust which has left minimal clearance which is a clonking occasionally...I asked the mechanic if he had checked the whole suspension set up, which he had, but then I asked him if he had seen any cats, to which he replied that he hadn't......where are the little devils ?? It passed the emissions test last month fine so I'm a little confused!!

[kris450]

Problem is you can't see them as they are inside the manifolds and y-piece. The large main cat is in the big dustbin part of the y-piece, just below where the 2 'y's meet. The smaller pre-cats are in the manifolds just after the 4 into 1 pipe section and before the bends with the lambda sensors as per the below.

Would tapping on the pipes produce a hollow sound ? Possibly but I'm not sure. Then again, if you passed a legit emissions test then its more than likely the main cat is still in at the very least.

Hope that helps

[silverback mike]

Lovely job thank you!!

[Classichims]

Either you've got a very healthy engine and or the main Catt is still in place, if there's an extra weld around main Y piece dustbin area it's likely to be de Catted.
As the pic above shows, you can just see the Pre cats( honeycomb) inside each manifold.

Personally my car works well with main cat in place and pre cats removed, it's got more tork than with a full catted( original Y piece) but less Bhp. Well that's how it feels!

[silverback mike]

Thanks chaps, I'll stick my head under the bonnet

[ChilliWhizz]

General consensus is that removal of the pre-cats will not affect emissions for MOT time as the car is emission tested when the engine is at running temp and the pre-cats (I believe) are only there for emission control when the engine is started from cold. Allegedly.

What makes you think it has had cats removed? As said above, if you have the original Y piece and it hasn't had a cut and shut then your main cat will still be in there... and the fact that you passed the MOT emissions would suggest that this is the case... Again, general consensus is that removal of pre-cats will change the exhaust note, and (again, allegedly) lower under bonnet temps, although I'm not sure there's been any before and after temperature measurements that prove this...

In my opinion, which is completely unbiased removal of all cats (with Clive F Y) but retaining original silencer gives the best possible soundtrack, but obviously gives an emissions issue...

Chilli

[silverback mike]

Thanks chaps, I'll stick my head under the bonnet