R129 SL500 Centre muffler delete and new cats

[Petrol Pete]

I have discussed the 'non standard' exhaust thing with my friend who has two MOT stations. His answer (paraphrased) is something like this...

"It's highly unlikely that I will end up in court for passing a car with a noisy exhaust , letting one go out with faulty brakes , suspension or seatbelts ? different story"

 

[BTB 500]

Per the regs. though they are definitely allowed to fail an exhaust for being too noisy if they want to. But I couldn't find anything to support an automatic fail for anything non-standard / aftermarket on the system - this would put every exhaust centre in the country out of business!

 

[SLBrighton]

This is correct, even aftermarket exhausts are not strictly legal but it is a bit of a grey area IMO.

You can't get the original cats from Mercedes now, so it makes it difficult.

 

[SLBrighton]

I'm also with Admiral at the moment, but was with LV until last year and they weren't interested in details either. Both standard policies rather than classic ones.

I've only ever had positive comments about the exhaust on mine, including from MB Guildford who have maintained and MOT'd the car since I got it in 2004. When it was in for service a couple of years ago I had a call from them asking if I would consider selling it!

Can I ask what you are paying on a standard policy with Admiral. It might be worth changing it to a classic policy. I was originally quoted a renewal of £350 for a fully comp, full no claims, 47 yrs old, 10,000 miles a year, parked in a driveway, with a second driver on the car. I changed to their classic policy, exactly the same terms and with an agreed valuation of £12,000 and it dropped to £138 a year.

 

[Martyn_n]

Per the regs. though they are definitely allowed to fail an exhaust for being too noisy if they want to. But I couldn't find anything to support an automatic fail for anything non-standard / aftermarket on the system - this would put every exhaust centre in the country out of business!

There is legislation that states that a replacement catalytic converter fitted to any car registered after 1st March 2001 has to be type approved to the specific vehicle. The ones on the OPs car would not meet that criteria on a post 1/3/2003 car and should fail an MOT test. Indeed it would be an offence to actually supply one unless labelled as not for road use. Not sure if this is enforceable in Scotland.

 

[SLBrighton]

There is legislation that states that a replacement catalytic converter fitted to any car registered after 1st March 2001 has to be type approved to the specific vehicle. The ones on the OPs car would not meet that criteria on a post 1/3/2003 car and should fail an MOT test. Indeed it would be an offence to actually supply one unless labelled as not for road use. Not sure if this is enforceable in Scotland.

My car is a '97. The garage are an authorised Longlife and classic sportscar service centre. They know the car reg and fitted according to the car, so assume all will be ok. I don't think they would be allowed to fit cats that are not suitable. You can't buy the replacement cats for R129's now from Mercedes, so you can only fit aftermarket ones.

 

[Martyn_n]

My car is a '97. The garage are an authorised Longlife and classic sportscar service centre. They know the car reg and fitted according to the car, so assume all will be ok. I don't think they would be allowed to fit cats that are not suitable. You can't buy the replacement cats for R129's now from Mercedes, so you can only fit aftermarket ones.

Yours is fine and I may do the same on my 124, I just wouldn't want someone with a post March 2001 (Not 2003 as I incorrectly wrote) to be surprised if they fell foul of the regulations.
It is possible to buy after market catalytic converters that are type approved so the fact they are NLA from Mercedes would not stop someone from complying with the regs.

 

[Doodle]

I've seen 2 different "type approved" systems from manufacturers for mine, neither of which I would trust beyond propping open my shed door. One of them clearly had never even seen the car they were designing it for, just worked off a crude image by facsimile as the unions were the wrong way round!

 

[SLBrighton]

I've seen 2 different "type approved" systems from manufacturers for mine, neither of which I would trust beyond propping open my shed door. One of them clearly had never even seen the car they were designing it for, just worked off a crude image by facsimile as the unions were the wrong way round!

SL Shop used to sell a system and they have even stopped that now as they were failing MOTs a year later!

 

[flowrider]

I recall reading that the cars emission system must not be modified in any way therefore aftermarket exhausts are not strictly legal as surely changing the exhaust for one not supplied as per the factory design is a modification. Similarly a car that originally came equipped with 4 CATs can have 2 CATs removed, a common modification, and so should logically fail an MOT but they hardly ever do as long as there are CATs still in place. I have been told that the rules dictate that a CAT equipped car must have CATs in place but the rule doesn't state how many.

 

[BTB 500]

Can I ask what you are paying on a standard policy with Admiral. It might be worth changing it to a classic policy. I was originally quoted a renewal of £350 for a fully comp, full no claims, 47 yrs old, 10,000 miles a year, parked in a driveway, with a second driver on the car. I changed to their classic policy, exactly the same terms and with an agreed valuation of £12,000 and it dropped to £138 a year.

I paid £196 for a standard policy, but things like your postcode affect it a fair bit. That was full no claims, second driver, garaged overnight but quite low annual mileage (2,000 or 3,000 IIRC).

 

[BTB 500]

I recall reading that the cars emission system must not be modified in any way therefore aftermarket exhausts are not strictly legal as surely changing the exhaust for one not supplied as per the factory design is a modification.

I posted a link to the MOT details before - the bit about modifications only applies to "emission control equipment" (cats etc.) on the exhaust system. It's under "Exhaust Emissions", and the two fail defects are:

(a) Emission control equipment fitted by the manufacturer: missing, obviously modified or obviously defective
(b) An induction or exhaust leak that could affect emissions levels


For the exhaust system in general the fail defects are:

(a) Exhaust system has a major leak or is insecure
(b) Exhaust fumes:

(i) entering cabin​

(ii) causing a danger to health of persons on board​

Then specifically for the "noise suppression system" (comprising exhaust silencers and under-bonnet noise deadening material):

(a) Exhaust noise levels in excess of those permitted
(b) Any part of the noise suppression system:

(i) insecure​

(ii) likely to become detached​

So a loose under-bonnet sound deadening pad should be an MOT fail, which I suspect isn't widely known!

 

[R129mine]

my middle box is rattling and squeaking but both Cat's were replaced in quick succession somewhere around 2014/2015 (cattle grid bar was loose and punctured one of them, £800 repair) but am now looking at either replacing the rear or just the middle section (deleting the rusty centre box).

I think I will start off with deleting (sorry such an USA youtube word) the rusty centre box and see how I get on

 

[SLBrighton]

my middle box is rattling and squeaking but both Cat's were replaced in quick succession somewhere around 2014/2015 (cattle grid bar was loose and punctured one of them, £800 repair) but am now looking at either replacing the rear or just the middle section (deleting the rusty centre box).

I think I will start off with deleting (sorry such an USA youtube word) the rusty centre box and see how I get on

The garage that I went to cut out my middle box as it was also quite rusty. The rear main box is in good condition still. You're correct that the cats are not cheap. It cost me just over £1000 including VAT for 2 new Longlife cats, remove the centre box and make a new Y shape stainless pipe. I did get the cats back, so I am going to take them to a recyclers and see if I can get something for them, although they are very rattly, which I am sure will reduce their value!