Failed MOT

dandywarhol · Post by **dandywarhol** » Wed Nov 21, 2007 12:56 pm

I know its going off topic a bit but what are your thoughts SM (and others

) as to why the veg oil smells so much more than pure diesel?

The performance/ecomomy (

) seem the same as diesel, the engine runs a tad quieter, the emissions are lower - so why does it whiff so much more?????????

bigdaddycain · Post by **bigdaddycain** » Wed Nov 21, 2007 1:01 pm

Bongoflyer wrote:Hi bigdaddy, yes I am a tester. Smoke tester is for diesels only.

mmmm, interesting post, as dandy said if your engine was so clean on the first run, (its called a fastpass) max 150ppm, then no need to continue on to the full six run test, why try to get a higher reading when you've got a pass. Maybe the chap was inexperienced.

The diesel smoke test is very far from rocket science and most vehicles pass it unlike the petrol test which is far more detailed and critical. I can usually tell if it'll pass the smoke test just by looking at the exhaust.

Hi bongoflyer, the chap whom carried out my m.o.t said that the smoke machine was linked to the computer,and that 5 full throttle runs was compulsory, otherwise the computer will say no...

The guy was extremely thorough!... He's a middle aged bloke, i got the impression he was experienced.

Having said that, he adjusted the headlight aim, (bongo had just been lowered)and on my first night time run, i thought the aim was TOO low...

dandywarhol · Post by **dandywarhol** » Wed Nov 21, 2007 1:09 pm

He's wrong then BDC! If the reading is lower than 150 PPM on the first run then the test is over. Any more is wasting time and your juice

Maybe the first run was over 150............

bigdaddycain · Post by **bigdaddycain** » Wed Nov 21, 2007 1:34 pm

I dont remember the actual first figure dandy, i was starting to panic a bit because i had TEN full rev runs in as many minutes,there was a wisp of smoke on the very first rev,then nothing else on subsequent revs.

My bongo had been idling for 45 minutes too,as cars had to be shuffled around to get access to the ramp.

I'd been running on 30% veg oil for about a month at that stage,and the egr was still in place then.

I got a pass, and like i say, the fella couldn't beleive my bongo was running so clean,that suggests to me that it passed on the first rev...

I think i'll try somewhere else next time...

jonb · Post by **jonb** » Wed Nov 21, 2007 2:50 pm

Good news, it's passed it's MOT now. As others suggested, the EGR valve was sticking. I've disabled it by disconnecting the vacuum pipe and the electrics. When I get round to it, I'll blank it off with an Allans Vehicle Services kit I reckon. As soon as the EGR was disabled, the MOT smoke readings were fine.

Many thanks for everyone's input, looks as though this thread has started an interesting discussion on emissions.

Cheers

Jon

mikeonb4c · Post by **mikeonb4c** » Wed Nov 21, 2007 3:27 pm

Fantastic jonb. Imagine deaing with these issues without the folk on this forum eh? Doesn't bear thinking about

smartmonkey · Post by **smartmonkey** » Wed Nov 21, 2007 4:31 pm

The veggie oil smell is actually a very scary thing. You do put out much less harmful emissions when running on veggie - it is a cleaner burn and a much simpler carbon source to start with. The only reason you can smell it more is because it smells more. Petrochemical emissions are virtually odour free but you get about the same amount of them.

The scary bit is because if you can get a whiff of veggie as it flies past imagine how many fumes you cant smell you are breathing in. The veggie smell really brought home to me just how polluted our air is.

Bongoflyer · Post by **Bongoflyer** » Thu Nov 22, 2007 12:32 am

Hi bongoflyer, the chap whom carried out my m.o.t said that the smoke machine was linked to the computer,and that 5 full throttle runs was compulsory, otherwise the computer will say no...

Tis true, the smoke tester has its own computer and will continue the test if it fails the fastpass, but that goes against what he said about a clean engine. The extra runs are there to help us get it through the test not the other way round.

The guy was extremely thorough!... He's a middle aged bloke, i got the impression he was experienced.

Yep, there's thorough and there's sensible, we hear this sort of thing quite a lot, I had a fella came in and said another local garage had failed his car on the stitching coming out of the steering wheel cover, I passed it. We can fail on steering wheels if it can damage the drivers hands, remember the old bakelite wheels, but the stitching, Pleeeese.

I think you already answered this yourself BDC, take it somewhere else next time.

bigdaddycain · Post by **bigdaddycain** » Thu Nov 22, 2007 5:28 pm

I might just do that bongoflyer...thanks

rob and karen · Post by **rob and karen** » Fri Nov 23, 2007 8:27 pm

on our mot the other week the tester put an oil dipstick probe inplace of the dipstick to do the emmisions test is this normal ?

rob

francophile1947 · Post by **francophile1947** » Fri Nov 23, 2007 8:43 pm

rob and karen wrote:on our mot the other week the tester put an oil dipstick probe inplace of the dipstick to do the emmisions test is this normal ?

rob

Yes - it's just to make sure the oil has reached full temperature.