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Thread: MOT and Emissions test

  1. #1
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    MOT and Emissions test

    In another post I detailed a problem I experienced with my wifes 451 Highstyle failing its MOT on the emissions test and the work I had done to try and eliminate the problem on the advice of the centre.

    The other day it passed, and the tester said that it was normal for them to take all vehicles which had were known to have emission test issues on a 10-15 minute run to warm them up before doing the emission test.
    He did this with our car and it passed with flying colours.

    My question is - is it normal/acceptable practice for testers to get the car hot before doing emissions testing, and for cars which show emissions problems to be taken for a run - or would revving in the workshop achieve the right temp level.

  2. #2
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    The test involves sticking a temperature sensor down the dip stick hole and it has to be a minimum temperature before the test is done (IIRC that is 80c minimum). Personally I take all cars for at least a 10 mile Italian service on the way to the MOT station and get them to do the gas test as soon as I get to the MOT station and generally do not have any problems. It is not normal for the MOT testing station to take it for a ride as far as the MOT itself goes, it is just a good service for them to offer if they are prepared to do it.

    My Smart is a particularly frozen little git and takes a lot of getting to normal working temperature plus it drops down again very quickly. It's a diesel thing that has a petrol designed cooling system, far too efficient generally which is why my radiator is completely blocked off with a plastic sheet.

  3. #3
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    Quote Originally Posted by Mjolinor View Post
    get them to do the gas test as soon as I get to the MOT station .
    My preferred method also though if MOT tester isn't quite ready, a trip up the road and back and then straight to emissions test suffices. Not necessarily amenable to leaving car - which is why waiting during test is becoming a preferred option - if its on the menu.
    MOT tester has the right to 'test drive' though rarely invoked.

    Cats thrive on heat - the more the better. I've yet to see proper engine temp monitoring during test implemented though an MOT tester will usually persevere until the engine is pretty hot. The pre-test drive though should put enough heat into everything such that the temp doesn't decay too rapidly.

  4. #4
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    Thanks guys.

    I think the tester who failed my wifes car twice (and whose recommendations cost me over £400) did not get the temp high enough. He only 'revved' the car for 3-4 minutes in an attempt to get the emission results to change enough to pass the car.

    Now they accept no responsibility saying they did the test correctly and any 'recommndations' were purely suggestions if they were not in writing.

    So I'm down a wad and their tester gets away with being incompetent.

  5. #5
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    If you were there when they did it and didn't see him stick the oil temperature sensor into the oil then you need to complain. He will get his hand slapped and you will get your money back unless they choose to do an independent test at a government MOT station in which case you may lose the MOT that you have.

    "Worth the risk" or "grump about it and move on"

  6. #6
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    Looking at the fail slips - ''coolant pipes hot'' and ''oil temp bypassed''. Sloppy. Not least because oil temp lags behind coolant temp.

  7. #7
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    Have to wonder which coolant pipes he is noting as being hot really on a 451.

  8. #8
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    Quote Originally Posted by pinger View Post
    Looking at the fail slips - ''coolant pipes hot'' and ''oil temp bypassed''. Sloppy. Not least because oil temp lags behind coolant temp.
    Quote Originally Posted by Mjolinor View Post
    Have to wonder which coolant pipes he is noting as being hot really on a 451.
    Sorry - can you elaborate. I'm not sure I understand these comments.

  9. #9
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    Quote Originally Posted by pewe View Post
    Sorry - can you elaborate. I'm not sure I understand these comments.
    From: http://www.ukmot.com/manual/7.3/Exha...k-Ignition#MOT
    And http://www.ukmot.com/manual/7.4/Exha...n-Ignition#MOT

    Diesel: The engine oil temperature measured by a probe in the oil level dipstick tube is to be at least 80C or normal operating temperature if lower 60C minimum. Testing an engine below normal operating temperature may affect the test result. If owing to vehicle configuration temperature measurement is impractical, the establishment of the engines normal operating temperature may be made by some other means, for example by the operation of the cooling fan or the engine block temperature measured by the level of infra-red radiation to be at least an equivalent temperature.

    Petrol: The engine must be at its normal idle speed and operating temperature when checking exhaust emissions. Engine speeds and temperature can be assessed either subjectively or by reference to manufacturers or other reliable data. It is important to ensure that the gas analyser probe is inserted as fully as possible into the exhaust pipe and is secure.

    The wording is a bit vague: Where the diesel tests are quite specific on temperature, the petrol test isn’t.

    However it sounds like he just entered what he normally enters on the sheet, ‘yeah engine was hot blah blah’
    You're so money supermarket and you don't even know it!

  10. #10
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    This is an area that is being clamped down on at this time. My MOT bloke happened to mention that the ministry were doing the rounds at the moment as he heated the sensor with his cigarette lighter before doing the test with the pipe stuck up the new car next to mine.

    There are no hoses on the smart that you can grab and tell if it is hot without opening the engine compartment and having done that it is probably easier to stick the sensor where it is supposed to go.

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