Catalytic converters

rab60bit · 16th August 2022, 11:14

Does anyone on here have a definitive answer:
Just had my intermediate exhaust system (cat. back to rear box) replaced (for I believe the first time - that's +171K/18 years it lasted for and it still wasn't blowing!).
It's a V6 2.5L and I understand there are two in-line cats. on the system - a small/short cylindrical mesh covered job and then a larger cylindrical box, tapered to the pipe at each end - two cats. is unusual unless there is a split system (which there isn't in the case on the V6 R75).
Any explanation or have I got it wrong.

Maxfly · 18th August 2022, 17:45

Quote:

Originally Posted by rab60bit

Does anyone on here have a definitive answer:
Just had my intermediate exhaust system (cat. back to rear box) replaced (for I believe the first time - that's +171K/18 years it lasted for and it still wasn't blowing!).
It's a V6 2.5L and I understand there are two in-line cats. on the system - a small/short cylindrical mesh covered job and then a larger cylindrical box, tapered to the pipe at each end - two cats. is unusual unless there is a split system (which there isn't in the case on the V6 R75).
Any explanation or have I got it wrong.

My understanding has been that the V6 manifolds have the pre cat then the main cat is inline just past the flexi section.
Generally when it was mainly just emissions that the mot checked you could remove the second cat and still easily clear the emissions test as long as the factory manifolds with the pre cat(s)? Was in situ

MSS · 19th August 2022, 13:15

Quote:

Originally Posted by rab60bit

Does anyone on here have a definitive answer:
Just had my intermediate exhaust system (cat. back to rear box) replaced (for I believe the first time - that's +171K/18 years it lasted for and it still wasn't blowing!).
It's a V6 2.5L and I understand there are two in-line cats. on the system - a small/short cylindrical mesh covered job and then a larger cylindrical box, tapered to the pipe at each end - two cats. is unusual unless there is a split system (which there isn't in the case on the V6 R75).
Any explanation or have I got it wrong.

Firstly, I am not an expert on the 2.5 V6 nor do I own one.

But, surely, the front part is just the flexi in the same way that there is one on the 1.8K and the diesel. The second box would be the CAT.

See. https://rimmerbros.com/Item--i-WCJ000391SLPP

Happy to be told that I am totally wrong!

bl52krz · 19th August 2022, 20:51

Strange arrangement I know, but there are two cats on the 2.5.

MSS · 20th August 2022, 10:45

Quote:

Originally Posted by bl52krz

Strange arrangement I know, but there are two cats on the 2.5.

So where is the second cat. Is it really in the flexi or manifold or somewhere else?

StewartIngram · 20th August 2022, 17:41

I've just stripped my old KV6, and taken the complete exhaust off. The 4 branch manifolds (2 of them obviously) are just plain pipe. Next section is the flexi - can't see if anything is inside that. That couples to the 1st silencer (which I believe to be the cat), followed by the middle silencer (originally the triangular one), round the bends and finally the rear silencer & twin tail pipes. Soes this help?

16th August 2022, 11:14	#1
rab60bit Posted a thing or two Rover 75 Saloon & Tourer Join Date: Mar 2013 Location: Wilmslow Posts: 1,513 Thanks: 433 Thanked 301 Times in 212 Posts	Catalytic converters Does anyone on here have a definitive answer: Just had my intermediate exhaust system (cat. back to rear box) replaced (for I believe the first time - that's +171K/18 years it lasted for and it still wasn't blowing!). It's a V6 2.5L and I understand there are two in-line cats. on the system - a small/short cylindrical mesh covered job and then a larger cylindrical box, tapered to the pipe at each end - two cats. is unusual unless there is a split system (which there isn't in the case on the V6 R75). Any explanation or have I got it wrong.

19th August 2022, 20:51	#4
bl52krz This is my second home Rover 75 cdt club + Rover 2.5 KV6 Conni SE Join Date: May 2008 Location: Birmingham Posts: 11,387 Thanks: 6,587 Thanked 2,262 Times in 1,729 Posts	Strange arrangement I know, but there are two cats on the 2.5. __________________ Great Barr, Birmingham.

20th August 2022, 17:41	#6
StewartIngram Gets stuck in Rover 75 Connoisseur 2.5 V6 auto Join Date: Jan 2008 Location: Chatteris, Cambridgeshire Posts: 902 Thanks: 320 Thanked 159 Times in 127 Posts	I've just stripped my old KV6, and taken the complete exhaust off. The 4 branch manifolds (2 of them obviously) are just plain pipe. Next section is the flexi - can't see if anything is inside that. That couples to the 1st silencer (which I believe to be the cat), followed by the middle silencer (originally the triangular one), round the bends and finally the rear silencer & twin tail pipes. Soes this help?