Motoring Discussion > Nearly forgot first MOT. Miscellaneous
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 Thu 17 Mar 11 19:13 
 Nearly forgot first MOT. - -
There we were sailing merrily down the M1 last Saturday in SWM's little C2 Diesel when suddenly warning bells go off in what passes for my mind...MOT.

It's 3 years old this month and i couldn't for the life of me remember when it was due, phoned the dealer who supplied it used to us and they quickly looked it up..phew, due 15th.
So SWM got it booked in first thing yesterday 16th, it passed OK with no advisories as it should at 3 years, but just shows how easy it is to be illegal.

Incidentally, it seems to have had a proper Diesel smoke test, which i don't recall receiving with a Diesel before, or has the print out smoke test report been the norm for a while.

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 Thu 17 Mar 11 19:35 
 Nearly forgot first MOT. - ....
Smoke test has been done on mine at every MOT since the first in 2007.
I think they have been standard for a long time though as I remember cambelts snapping on older diesels when the test was introduced.
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 Thu 17 Mar 11 19:44 
 Nearly forgot first MOT. - -
>> Smoke test has been done on mine at every MOT since the first in 2007.
>>

That might explain it, the pick up was new in 2007 so i haven't had a Diesel MOT'd till August last year.

I did wonder if this was the Diesels emissions test that was discussed some time ago, or is that yet to come?
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 Thu 17 Mar 11 19:45 
 Nearly forgot first MOT. - ....
September '95 was when the smoke test was introduced for diesels.

At the minute it's not really an emissions test, rather a smoke density test.
Last edited by: gmac on Thu 17 Mar 11 at 19:46
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 Thu 17 Mar 11 19:47 
 Nearly forgot first MOT. - -
>> September '95 was when the smoke test was introduced for diesels.
>>

Blimey, my memory is worse than i thought, i know they always revved the hell out of them and checked for visual smoke, but couldn't recall getting a print out before.
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 Thu 17 Mar 11 19:53 
 Nearly forgot first MOT. - ....
I'm not sure when the printout was introduced. I've always had one with mine. Testers have told me they have a pretty good idea if a car is going to pass or not before they even hook it up.

I usually time my MOT to coincide with coming off the back of a ten hour run when everything is nice and hot.
Last edited by: gmac on Thu 17 Mar 11 at 19:56
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 Thu 17 Mar 11 19:57 
 Nearly forgot first MOT. - Iffy
I believe the smoke test involves revving the engine up to the limiter.

Not something I would do to my car, and I don't suppose gb would do it to his.



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 Thu 17 Mar 11 20:00 
 Nearly forgot first MOT. - -
>> I believe the smoke test involves revving the engine up to the limiter.
>>

Yep the print out mentions 4990 rpm, poor little thing.

It came off a 200 mile run last weekend, so should all have been clean and dandy.
Last edited by: gordonbennet on Thu 17 Mar 11 at 20:01
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 Thu 17 Mar 11 20:01 
 Nearly forgot first MOT. - ....
That's right, see point 24 in the link.
tinyurl.com/64lvsyh (Haynes MOT Info)
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 Thu 17 Mar 11 20:04 
 Nearly forgot first MOT. - Zero
>> I believe the smoke test involves revving the engine up to the limiter.
>>
>> Not something I would do to my car, and I don't suppose gb would do
>> it to his.

Did it with all my diesels. None of them were smokey or had gummed up EGR valves.
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 Thu 17 Mar 11 20:21 
 Nearly forgot first MOT. - Iffy
I wonder where you stand if it goes bang while the MoT tester has got the valves bouncing?

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 Thu 17 Mar 11 20:26 
 Nearly forgot first MOT. - ....
Note: it is of the utmost importance that the engine timing belt is in good condition before the test is carried out.

There were a few did go bang in the early days. It was put down to poor maintenance and the reason why the tester usually asks you to confirm the health beforehand otherwise they can refuse to test.
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 Thu 17 Mar 11 22:09 
 Nearly forgot first MOT. - Dave_
>> I usually time my MOT to coincide with coming off the back of a ten hour run when everything is nice and hot

I've found a nice, impartial, cheap MoT testing station 10 miles away. The run over there makes sure my car is nice and hot when I present it for its test. My dad always used to do the same with mum's car for the same reason, it was the longest journey it made all year.

>> I believe the smoke test involves revving the engine up to the limiter.
>> Not something I would do to my car

A diesel engine cannot be over-revved by design. Saying that I still winced when the test station tried it with my old minicabs.

My Escort (petrol) needed revving to 6000rpm+ to pass its fast idle emissions last May, accompanied by a strong smell of engine death. I'll check its MoT status later on this year after the anniversary, if it survives another one the buyer will have had a bargain when all's said and done.

The Mondeo is chain cam, no belt to snap :)
Last edited by: Dave_TDCi {P} on Thu 17 Mar 11 at 22:10
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 Thu 17 Mar 11 22:22 
 Nearly forgot first MOT. - Bellboy
A diesel engine cannot be over-revved by design
>>>>.
>>>>>>>> its not the over revving thats the problem dave,its the fact there is no load on the crank so its an unreal test for a diesel
it make me wince that in 2011 we still have a system for checking diesels from the stone age
and they cant even get their it sorted vosa has been down all day today and dvla were down all morning
thankfully these systems arent based in south east asia




or are they
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 Thu 17 Mar 11 22:31 
 Nearly forgot first MOT. - Number_Cruncher
In fairness Bb, if you want to make a diesel engine produce much out of its exhaust pipe, you need to be squirting some fuel into the cylinders. Short of forcing MOT stations to fit rolling road dynamometers to load the engine up, giving an unloaded engine a good revving is a reasonable and pragmatic alternative.

As per usual, the MOT is actually quite sensible and proportionate.

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 Fri 18 Mar 11 09:24 
 Nearly forgot first MOT. - Cliff Pope
From observation, ie being stuck behind a bus as it pulls away, diesel engines make most smoke when they are revved gently from idle. The smoke clears when revved freely.
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 Fri 18 Mar 11 10:57 
 Nearly forgot first MOT. - Number_Cruncher
That's oil build up in the exhaust after a period of idling being blown out by revving the engine - you would see that smoke during a smoke test if the engine had been idling for a minute or two first. i.e., it's the period of idling that makes the smoke, not the fact that the bus is only revving gently.
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 Fri 18 Mar 11 12:35 
 Nearly forgot first MOT. - Boxsterboy
It's easy to forget the MOT if it's out of synch with tax renewal. If DVLA they can send tax reminders, why not MOT reminders? Is it because tax reminders bring in money, whereas MOTs are just about boring (and less profitable) road safety?
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