Dreaded PO420 Returned

[Dev]

There is a way to test the cat if you believe that the problem is the cat.
 You simply add an anti fouler to the 02 sensor. They are cheap and easy to instal. If no CEL is tripped you have a bad cat. If the CEL is tripped its the 02 sensor or wiring.

 What the anti fouler does is space out the 02 sensor so it samples less exhaust gases. This is useful for those that run sports cats that trip the CEL because they are on the border of not being an efficient catalyst.
 

[normanh]

Thanks, looks like its going to be the Cats 4 U model , a darn sight cheaper as well.

Norman

[normanh]

I assume its best to remove the back bumper to give a better access?  Whats the threads size on the manifold to catalyst, I guess mine will be useless and studs will want drilling out, I'll likely fit stainless.

Norman

[Carolyn]

I assume its best to remove the back bumper to give a better access?  Whats the threads size on the manifold to catalyst, I guess mine will be useless and studs will want drilling out, I'll likely fit stainless.

Norman

You really don't need to remove the bumper.  You can get at all the bits you need to get at from underneath and on top. Get it as high as you can on Jack-stands and put something soft down to lie on.  Spray all the nuts and bolts, including the ones that join the cat to the back-box, (which shear as often as the manifold to cat bolts). With Plusgas ( it's the dog's), drop it back down and re-visit in a couple of days.  Hot Plusgas works wonders

Odds are, you might be pleasantly surprised as to how it comes apart. (if not -hey-ho get the drill out.)  As I recall its an M10 but I don't recall the pitch.

Worry not, it can all be through-bolted if it should come to that.

I cut the old rubber mount off with a Stanley knife and put on new bog-standard one from the local parts shop.  Plenty of Fairy liquid.

You can use other brands.

[normanh]

I intend to bolt through anyhow Carolyn in stainless, what length bolts would I need. In this case pitch wont matter? I cant get underneath at the moment due to a bad case of vertigo due to a ear problem so its down to my son a plant and vehicle fitter so it shouldnt be a problem for him

Norman

[Carolyn]

I intend to bolt through anyhow Carolyn in stainless, what length bolts would I need. In this case pitch wont matter? I cant get underneath at the moment due to a bad case of vertigo due to a ear problem so its down to my son a plant and vehicle fitter so it shouldnt be a problem for him

Norman

35 -40 mm

[normanh]

Anyone have a link for genuine crush rings for the cat to manifold joint? Save me the job of dragging out to a Mr T, the local one isn't a big favourite of mine

Norman

[Joesson]

Anyone have a link for genuine crush rings for the cat to manifold joint? Save me the job of dragging out to a Mr T, the local one isn't a big favourite of mine

Norman

https://www.tcbparts.co.uk/

Probably best to telephone:
01579 383879

[Ardent]

@normanh what ^^^^ said.

[normanh]

Changes the cat today, due to a reoccurring back injury my mechanic son did the technical stuff working in a pit - I couldn't even get down the stairs into the pit today. The exhaust side came off pretty easy but the manifold was an absolute pig. One stud sheered off with the minimum of torque the others just would not yield ending up with new nuts being welded on and heat applied with a cutting torch before these two yielded by sheering off. This necessitated the need to drill out 2 for a clearance hole and the 3rd was re-tapped to 10mm. I was surprised to find that the studs were actually stainless steel. Nuts and bolts replaced with A2 stainless and washers. Took about 2 1/2 hours. Noticed how quiet the car is now as there was evidence seen that the manifold flange had a very slight blow since - joint was pasted! I first surveyed the job earlier in the year no obvious leaks. I know for a fact that the engine was replaced at a date sometime in 2002/3 at 22K miles. This seal wouldn't have lasted much more in all honesty So its now wait and see what emissions this cat gives. So a big thanks to the son here

Norman

[normanh]

Emissions perfect so looks like a problem suitable solved. And my back aches better today lol.

Norman

[Joesson]

Emissions perfect so looks like a problem suitable solved. And my back aches better today lol.

Norman

Pleased to hear everything is back up and running OK.

[normanh]

Went to weigh in the old cat at a local scrapyard and after a lot of crap like its empty, its not a genuine cat, it must have a F number stamped in the body, cutting off the shields looking for this magic number none found on the body, a part was found on the shield, I was offered £20 definitely taking the wee wee. I sold a Peugeot one off a early 405 GTX for £25 an that was over 15 years ago. I put an angle grinder over it with a brush nothing!

Is there a stamped number, I think its on part of the shield which is welded to the to the end where the flex's are. Definitely none under the shields. What numbers can be expected? I think these were just rip off merchants, there must be a master bible they use depending on the car?

Norman

[normanh]

Can anyone provide me with the stamped on number to the lower heat shield by the flexi joints to the manifold please my old one is so corroded I cant read it, thanks.

Norman

[Erudite]

Getting the same code after fittings a cats2u from eBay. Most likely to be a damaged sensor after removing and refitting during the cat installation?

[Carolyn]

Probably. They rarely survive being extracted from the cat.

[normanh]

Just thinking ahead so as I can weigh in the cat at a scrapyard and not have the p taken again.

Norman