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Discussion Starter #1
hi

my car has failed its MOT as the cat which is at the downpipe is knackered. I need to remove and fit a replacement.

i'm hoping i can do this job myself - is it easy enough to get access to and remove from its position with the engine in place?

thanks

derek
 
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Which cat are you looking at swapping? One of the manifold cats, which don't really do much and if so, which one (front or rear bank?) or the main cats under the car?
 

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Discussion Starter #3
not sure. where the pipes appear from some heat shielding under the engine (ie the bend from the vertical downpipe to the horizontal exhaust pipe) is GLOWING red hot and the garage say they cant get a reading for MOT emissions because of it - the exhaust is also puffing a lot and i think its struggling to get rid of the exhaust gasses. car drives OK but stutters occasionally also. They say its caused because the cat is blocked.

i thought if one is blocked then it would glow red BEFORE the offending cat???? but there isnt any cat until half way along the car after that, so my only guess is its the one on the verticle pipe from the engine which is shielded by the heat shield????

thanks for any advice/help you can give. my hope is to remove the offending part and replace it with a good 2nd hand item, or maybe de-cat the blocked one?????
 

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Perhaps a cat has disintegrated inside? I've not heard of a normal car getting glowing exhaust pipes (although I wish mine did as that is utterly wicked cool!!!) but it would REALLY block exhaust gases. Usually on higher revs though. Puffing? What colour?
 

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Discussion Starter #5
although I wish mine did
OK cool, swap your car for mine anytime!!

the car failed to start for the garage after the MOT. but when i went to pick it up (ready to have to tow it back) it started fine and drove home (about 1 mile). i suspect as it had cooled down it allows gases through again.
 

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My 156 lasted 2 days and is in Car Heaven now. Now, my Twin Turbo Legacy, that's a quick car! ;)

Whap the exhaust (lightly) with a hammer, hear any thing rattling around inside? Do not hit the cat though! Deffo sounds like something has collapsed inside...
 
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If its a 2003 v6 then it should be a Cf3. Cf3 v6's have 4 cats, 2 in the exhaust manifolds and 2 under the car, under where the front seats are.

A glowing exhaust can also be caused by a misfire as it results in unburnt petrol being ignited in the cat.

Removing the cats under the car is straight forward untill you factor in 9 years worth of corrosion which will likely mean all the nuts and bolts are corroded. An angle grinder, taps, dies, new studs and new nuts are normally required.

Removing the front manifold is a pain in the donkey, removing the rear manifold is nigh on impossible without dropping the engine.
 

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Discussion Starter #10
its actually a 52 plate (2002) but it is a facelift model (facelift interior etc)..... i assume that means its the 2003 type?

if the connections are standard exhaust fittings them i'm OK as i've refitted a few exhausts in my time, but only on non-cat cars (classics)

i'll get my grinder ready ;)

if i remove the connection just after the downpipe (basically where it goes from a vertical pipe to the horizontal pipe) and that breaths freely i guess that means its the centre cat/cats at fault?

cheers

derek
 
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