pre cat removal

[poorpeet]

Am i correct in saying that removal of the pre cats will not cause problems at MOT time as they are only required to allow a cold engine to pass the emmisions test?
If so I'd like to remove mine. Both were very loose when I took off the manifolds in order to replace the exhaust gaskets & were mashed on the exposed end from hitting the inside of the manifold.
I think I read a while ago that it was possible to remove them without cutting and rewelding.
Can anyone enlighten me on this point?
Cheers
Pete

[The Surveyor]

Taking out the pre-cats does not effect the MOT, i've got the ACT modified manifolds on mine (the ones with the reverse cones in) and it's been through an MOT without any trouble. They are only there to clean up the exhaust before the main cat warms up, and the MOT stations should always test a car when it's fully warm.

You can take them out without cutting, by carefully smashing them up within the manifold. But take care not to bash a sharp object through the side of the manifold, and you should also avoid breathing-in the dust, or getting it on your skin. The ceramic cat' has some nasties in it apparently which may bring you out in a rash.....

If yours are loose in the manifolds, you may also want to take out off the 'Y' peice and check that isn't obstructed with bits off the pre-cat which has dislodged (turn it upside down and give it a knock!).

Paul

[poorpeet]

Cheers Paul

[crazycraig]

See if this helps.

www.pistonheads.co.uk/gassing/topic.asp?p=1&f=13&t=228906&h=0

[adam459]

mine were both loose, making a nasty knock on acceleration. we took out my y piece and you could see the cats moving, so with a little persuasion and a hammer and long chisel we managed to get them out. didn't need any welding, but make sure you remove the lambda sensors before you start, i forgot about this and had to pay the price.

[andy-w]

I was lucky with mine....i took the Y section out and found that the LH manifold had a very lose pre-cat that took about half hour to get out and the RH manifold never had one in!!!

After looking around i found it lying on top of the main cat in the Y section!!!

[cre]

adam459 said:

mine were both loose, making a nasty knock on acceleration. we took out my y piece and you could see the cats moving, so with a little persuasion and a hammer and long chisel we managed to get them out. didn't need any welding, but make sure you remove the lambda sensors before you start, i forgot about this and had to pay the price.

Oh yes...a very special way of removing the pre cats!


Jamie

[cre]

Adam,
YHM

Jamie

[andy-w]

Must admit Adam, i used the more subtle approach...mole grops and tin snips...just kept cutting away at it and eventually got it past the recess for the lambda censor...!!!

But a hammer and chisel is good

[adam459]

you think hammer and chisel is good for removal of pre-cats you should of seen how i had to get rid of the main bugger it took a grinder, drill and 6 new bits and to top it off an industrial air pick. in the end, it lost. sounds much better now though.

[Nick P]

so, am i correct in concluding that.....

a) It will not affect the MOT
b) It will not have any detrimental effects
c) It will make my Chim slightly louder
d) It will make the engine breathe easier and hence release more power
e) Is a pretty much 'free' way of attaining all these objectives

??????????????????????????

[old64er]

Nick P said:

so, am i correct in concluding that.....

a) It will not affect the MOT
b) It will not have any detrimental effects
c) It will make my Chim slightly louder
d) It will make the engine breathe easier and hence release more power
e) Is a pretty much 'free' way of attaining all these objectives

??????????????????????????

yes

[jem]

It does change the note slightly to a bit rougher/poorer, I reckon it's a good mod with a double plenum to really make it spit like a dog.

Lurvely

J

[IM]

Nick P said:

so, am i correct in concluding that.....
d) It will make the engine breathe easier and hence release more power

d) Er...dont know about that...I had the Pre's taken out and apart from a difference in the noise I dont see any power/performance gain.

[victormeldrew]

IM said:

Nick P said:

so, am i correct in concluding that.....
d) It will make the engine breathe easier and hence release more power

d) Er...dont know about that...I had the Pre's taken out and apart from a difference in the noise I dont see any power/performance gain.

Unless the pre-cats are blocked of course! Even if they're not blocked, they must be a restriction of sorts, but possibly not a measurable seta-of-the-pants measurable one.