Volkswagen Mark IV Forum banner
1 - 20 of 61 Posts

·
Jetta family.
Joined
·
911 Posts
Discussion Starter · #1 ·
As above, i have got to get a new front exhaust that goes from the CAT to the engine, but i was wondering if i de - CAT'D my Bora tdi pd 130, would it fail it's M.O.T?? It's a 2002/52 model and i need to know as soon as possible[:)] All help very much appreciated[Y]

Cheers, Shane.
 

·
Registered
Joined
·
290 Posts
i think this statement is correct.....

if the examiner just does the test and the readings are ok..then it will pass

if the examiner looks at the exhaust and notices there is no cat...he can fail it.

i take mine to a mate, who doesnt notice the de-cat nor the HID's without auto levelling :)

http://www.motester.co.uk/MOTQuiz.aspx
 

·
Registered
Joined
·
2,987 Posts
its a smoke test not a emissions test so unless there is exessive smoke then there is no problems and generally you only get smoke under load.
 

·
Registered
Joined
·
292 Posts
Has the MK4 got a cover under the engine?
I know with the MK5 if you were to fit a de-cat the MOT'er wouldn't be able to see if it had one or not.
However I guess if VOSA were onto you they can remove any cover they like for inspection?
 

·
I ate a big red candle !!
Joined
·
10,384 Posts
Mines never failed an mot withou the cat. [funky]
 

·
Livin' by the sword
Joined
·
5,180 Posts
i think this statement is correct.....

if the examiner just does the test and the readings are ok..then it will pass

if the examiner looks at the exhaust and notices there is no cat...he can fail it.
That is correct. In practice, the tester may overlook the fact that part of the exhaust is missing, while taking the view that as another piece of exhaust has in fact replaced the missing cat, it's actually a complete exhaust again. But in theory the exhaust is incomplete so could fail if the tester wanted to be an arse.
 

·
Registered
Joined
·
3 Posts
It is not a legal requirement in the UK to have a catalytic convertor fitted on any car nor is it illegal to remove one.

It is however a legal requirement to pass the exhaust emission test. Most modern cars will fail with the cat removed.

Your MOT tester cannot fail you for removing the cat provided you have a complete exhaust system that meets the basic MOT requirment and you pass the emission test.

See links for complete info

http://www.motinfo.gov.uk/htdocs/index.htm

http://www.motester.co.uk/
 

·
Mk4 for 13 years
Joined
·
993 Posts
i think this statement is correct.....

if the examiner just does the test and the readings are ok..then it will pass

if the examiner looks at the exhaust and notices there is no cat...he can fail it.
That is correct. In practice, the tester may overlook the fact that part of the exhaust is missing, while taking the view that as another piece of exhaust has in fact replaced the missing cat, it's actually a complete exhaust again. But in theory the exhaust is incomplete so could fail if the tester wanted to be an arse.
I agree with this. It totally depends on the examiner. I have just had my car pass its MOT in the past few days and asked this specific question. Yes if it passes the readings it will be ok, but if the examiner notices the lack of presence of the cat & is aware that one should be there then it can be failed. The reasoning mentioned (in terms that were made understandable to me) is that it has to be originally how the car intended to be. Mine has a cat and I now know I will have to try my luck elsewhere at MOT time if i de-cat!
 

·
Registered
Joined
·
2,987 Posts
It is not a legal requirement in the UK to have a catalytic convertor fitted on any car nor is it illegal to remove one.

It is however a legal requirement to pass the exhaust emission test. Most modern cars will fail with the cat removed.

Your MOT tester cannot fail you for removing the cat provided you have a complete exhaust system that meets the basic MOT requirment and you pass the emission test.

See links for complete info

http://www.motinfo.gov.uk/htdocs/index.htm

http://www.motester.co.uk/
diesels do not have a emissions test though. they have a smoke test. (the mot examiner just looks at the smoke generally or does not bother)

an mot'er will just ensure there are no holes within the exhaust system and ensure it is safe (secure) also if you had an extremely loud exhaust they may be awkward.

a cat is just there to get blocked up and ensures that people earn money from replacing them. the replacement cats are worthless as they are not made from the same grade materials of the genuine ones.

also when you get your cat changed or decated do you realise how much the broken/damaged cat is worth?

a certain lexus cat is worth £250 (scrap)
 

·
Registered
Joined
·
2,987 Posts
chris they dont generaly connect it up as its visable to determine the result.

a golf tdi cat does vary between 28-57 pounds over the year.

but the lexus cats are worth a fortune

there was a recall on them but not all were returned. which means they block get cut out and it goes in the christmas kitty.

last cat i had was an alfa 156 2.0 t spark which was worth £82
 

·
Registered
Joined
·
3 Posts
Cars before 1 August 1979 only have a visual smoke test. Cars after 1 August 1979 need to be connected to a smoke test meter.

<nobr>"After 6 free accelerations, the mean </nobr>
<nobr>of the last 3 smoke levels is: </nobr>
<nobr> </nobr>
<nobr>a. for a non-turbocharged engine, </nobr>
<nobr>more than 2.50m-1 </nobr>
<nobr> </nobr>
<nobr>b. for turbocharged engines </nobr>
<nobr>more than 3.00m-1"</nobr>

Note also you will fail if

<nobr>"The emissions cannot be measured </nobr>
<nobr>because a tailpipe accessory is fitted </nobr>
<nobr>or a deliberate modification has been </nobr>
<nobr>made which prevents insertion of the </nobr>
<nobr>smoke meter probe"</nobr>
 

·
Livin&#39; by the sword
Joined
·
5,180 Posts
its a smoke test not a emissions test so unless there is exessive smoke then there is no problems and generally you only get smoke under load.
+1
Yep, but there's a testing procedure for the smoke test, not just a gawp at the back end while someone revs the engine. There's also the exhaust inspection, which is where a decat will fall foul. If the tester sees a missing component then he can fail it. MOT testing stations are required to have the correct standard smoke test equipment. They should also be using it. Okay, so one or two places may just look at the exhaust outlet and say it's okay but that is not the test procedure, and if the car goes elsewhere for testing and then fails, then which one isn't doing their job correctly? Someone else has posted the smoke levels earlier in the thread, with the exception of the "fast pass" criteria where if a suitable reading is gained from the first acceleration run then this is registered as a pass. The results of the smoke test are electronically recorded on the computerised MOT system. Finally, there is also a visual check (regardless of test results) where the tester is required to "Assess whether the smoke emitted from the exhaust, regardless
of measured density, is likely to obscure the vision of other road
users."

As for diesel cats not doing anything, they convert carbon monoxide (poisonous) into carbon dioxide (much less lethal) and improve the air quality, amongst other things.
 

·
TEAM 88 MOTORSPORT
Joined
·
8,904 Posts
It will pass the MOT...it will also smell like an old London bus. My car stinks when its left to tickover. The smoke test is analyzed by a machine a sensor is put in the exhaust, this sample is analyzed over 3 accelerations to @ 4k rpm[C]
 
1 - 20 of 61 Posts
Top