gutted the cats on 2.5 V6 tdi today.. very interesting - pictures inside

[audi2.5tdi]

been having awful trouble with my car since buying it back in October, so today decided to removed the cats and gut them to see if they were to blame at all.. picture speak 1000 words!!

cats removed and cut open


pryed open to remove cat


cat removed


closed and stitched back together with stainless mig





now, i think you'll agree that there was a fair restriction!! both cats were the same, pictured is the front face of the cat (downpipe end) almost the entire face was like that, some of the caked soot was broken off when i removed the cat from the case with a screwdriver

the difference with the cats gutted is phenomenal! its like a new car!! exhaust note is not to different, no louder unfortunatly! theres no more smoke

 

[PAULF]

Well done - great pictures.

I keep thinking of doing mine as a 'Cat' on these cars is just silly!
Your pic shows just what a restriction it has once a few years have gone. Cats and EGRs are one of my pet hates.

 

[voorhees]

That was some neat cutting I end up allover the joint,that cat looks like a very busy beehive honeycomb no wonder the cars totally different.
No lights come up or MOT advisory ?

 

[audi2.5tdi]

Neat cut come from years of cutting sheet metal with a 1mm cutting disk on the grinder..

I've totally removed the egr valve and replaced the crank case breather, it smokes less than my 968 turbo on boost!!

No lights, MOT not due till July sometime, can't imagine a problem though (+ friendly MOT place next to my bodyshop)

The car is a totally different animal, from 1500/1750 -4500+ it's just a constant onslaught of torque in every gear

I'm hoping tho will have a positive effect on the MPG as on average I've been seeing 34-36mpg driving normal/grandad stylee..

 

[Gazwould]

It's bound to be better on fuel, do report back.

 

[audi2.5tdi]

I really hope so! I will report back

 

[crazyjay91]

I'm definitely going to do this. Just ordered a 1mm cutting disc to get a nice cut.. Just need to source a welder!

 

[crazyjay91]

Just a quick question... How thick do you think the metal is?? I've found a guy that has a welder but he said he's worried that it could be too powerful and tear a hole in the cat's housing..

 

[desertstorm]

If he has a MIG welder then it won't be a problem. If he has a stick welder then it will be an issue.

Karl.

 

[crazyjay91]

If he has a MIG welder then it won't be a problem. If he has a stick welder then it will be an issue.

Karl.

You sir, are a legend. Thank you!

 

[audi2.5tdi]

It is stainless steel and no more than 0.8mm thick

Don't forget mot now says cats must be there even on diesels and would suggest making sure welds can't be seen from underside of the car, stainless mig wire or tig is best as it also won't corrode!