Passing an MOT with a decat pipe

K

kat975

New user
Aug 8, 2012
1
0
Cannock
Hey everyone,

I was just wondering if its possible to pass your MOT with a decat pipe on? (I have a V6 if thats any help???)

Thank you
 
so long as the precats in manifold are there, you can remove one or the other but not both
a lot on here have passed so long as emmissions are correct
 
By the letter of the law.....no. However, most of the people on here running decats on the V6 have had no issues with MOTs. It all boils down to how much of a jobsworth your MOT man is. As far as the emissions go, provided it's serviced regularly it'll fly through the emissions test with the main cat removed and running off the precats on the downpipes (y)
 
Not sure if its relevent, but i've got a medium sized leak around where flexi pipe joins manifold downpipe and it passed mot fine. Aparently it's fine to have a leak in exhuast system as long as it's of a certain size and doesn't push emmissions past the limit :)
 
No it isn't, and if anyone tipped off VOSA your tester will be visited and if the spot-check inspector found any such mal-practice he'd lose his license. Construction and Use regulations clearly prohibit any exhaust gases leaving the car without first having passed through a silencer. The sentence in the regulations is written in plain English with no wooliness, so it's not open to interpretation whatsoever, and thus a flexijoint leak is an automatic fail.
 
jamie_duff said:
No it isn't, and if anyone tipped off VOSA your tester will be visited and if the spot-check inspector found any such mal-practice he'd lose his license. Construction and Use regulations clearly prohibit any exhaust gases leaving the car without first having passed through a silencer. The sentence in the regulations is written in plain English with no wooliness, so it's not open to interpretation whatsoever, and thus a flexijoint leak is an automatic fail.
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Yep, exactly what Si just told me, for changing my exhaust over soon, he said new gaskets, and some sealant as it can't leak, not even a little bit.. (y)
 
Well may be some MOT testers take it more serious than others ? But i was always under the impression the exhaust should never leak.. but your correct, that site does say otherwise.. (y)
 
Yeah its weird? If you google 'mot exhaust leak', all results say that a small leak is ok and only a fail if major leak or effects noise or emissions.

But then the Construction and Use regulations site does clearly state that any leak of gasses before passing through silencer is a no-no:

http://www.legislation.gov.uk/uksi/1986/1078/regulation/54/made

Are these regulations supposed to be the 'law' for mots? Or a sort of general set of rules regarding cars in the uk?
 
Oli Wright said:
Yeah its weird? If you google 'mot exhaust leak', all results say that a small leak is ok and only a fail if major leak or effects noise or emissions.

But then the Construction and Use regulations site does clearly state that any leak of gasses before passing through silencer is a no-no:

http://www.legislation.gov.uk/uksi/1986/1078/regulation/54/made

Are these regulations supposed to be the 'law' for mots? Or a sort of general set of rules regarding cars in the uk?
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The government legislations are the laws.. and set in stone rules for the MOT rules if you know what i mean..?
 
I get ya :)

And believe me I was very surprised when my car came back from garage with mot and the exhaust pipe I left on passenger seat for them to fit still on the passeger seat lol.
 
There are probably a lot of testers out there who do apply a lot of interpretation to things, whether it's there to be interpreted or now. Things like "excessive movement" in a bush, for example, are very subjective. Things like exhaust gas getting out ahead of the tail pipe are not really things you can interpret differently.

Ultimately, it comes down to the tester. Those who appear like "jobsworths" are just making sure they keep their testing licenses. Those who let things go are taking a (small) risk. It's like a taxi driver speeding - if you want to make sure you keep your livelihood you'll stick within the speed limits, but many taxi drivers will speed to some extent same as anyone else for that matter and it's really that individual's perception of the risk and consequence of being caught out.
 
jamie_duff said:
There are probably a lot of testers out there who do apply a lot of interpretation to things, whether it's there to be interpreted or now. Things like "excessive movement" in a bush, for example, are very subjective. Things like exhaust gas getting out ahead of the tail pipe are not really things you can interpret differently.

Ultimately, it comes down to the tester. Those who appear like "jobsworths" are just making sure they keep their testing licenses. Those who let things go are taking a (small) risk. It's like a taxi driver speeding - if you want to make sure you keep your livelihood you'll stick within the speed limits, but many taxi drivers will speed to some extent same as anyone else for that matter and it's really that individual's perception of the risk and consequence of being caught out.
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Agreed Jamie..
 
So is it possible to pass an MOT with no cats in place at all ( emissions ) ?
I have a place that will turn a blind eye to not having a cat but unsure if the emissions will come in under.
 
i'd say no, and then you'd get pulled up for no cats. The place I go to, they do the brakes, emissions, lights, and then put it on the ramps. If you fail the emissions, that could be down to the exhaust, the engine, Lamda sensor etc. They'd note that as a fail,and then stick up in the air,and then discover no cats, assuming they know about the precats aswell.

If you pass the emissions with precats, and then they find you have no main cat, then I guess it would depend on how stringent they are feeling.

I think a true picture of the decat issue will only emerge next year, after April when we have all had to go for an MOT.
Its been 7 months since the new rules applied, so in theory just over 1/2 the cars could have been for an MOT since. Mine was done just before April, before I fitted a decat. I'm tempted to just stick the cat in the boot and talk to them nicely if it fails. Its a 20 min job to switch over, but I'll be swapping back as soon as I get home conversation!
 
The other option is to fit stainless headers without the precats and fit a sports cat. Still emissions friendly. ;)
 
mine was done in may with a decat s/s twin exhaust and passed emmissions and pass test, as previous said if both are removed the emissions will be wrong.
you could argue that with the precats on you still have cats in the system, and if emissions are ok should get through, the two lots of cats fitted were to meet american higher emission laws
 
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