Diesel failed MOT on black smoke test PART 2

Penny_Farthing_2

Hi
Hope you don't mind this update. Story so far

http://forums.moneysavingexpert.com/showthread.html?p=11404397#post11404397

I changed the air filter. Car is booked in for oil and oil filter and fuel filter change tomorrow.

Went at 70 in third gear today about 10 mins in total (several bursts of a few minutes each). I didn't see smoke coming out of the back in my mirror. Straight after, I revved the engine when stationary (used the roof bar to press the accelerator pedal so I could look at the exhaust properly - brownie points for initiative?) and the smoke was hardly there at all. This was lunchtime.
I drove home after work at a normal speed (between 55 and 70).
I revved the engine when it was stationary at home (used son to press the pedal this time) and there was lots of black smoke.

Any ideas about what's causing the problem?
Am I clutching (sorry) at straws to think the changes booked in for tomorrow will help?
Should I be preparing my credit card for that ultra sound cleaning of the injectors costing hundreds?
Thanks

Please note all replies/instructions need to be in a 'beginner's guide' stylee;)

in2deep_2

Is it going for the MOT as well..??

Soot will accumulate in a engine if only used 'light' like pottering around town and short trips, it doesn't instantly mean there is something wrong with it but soot build up can cause its own problems.

If you get a chance take the car for its MOT at the time its booked in don't just leave it all day, the car needs to be hot when it gets there.
Ideally you would drive it very hard (like you have been) on the way for its MOT and time it so it going straight in for the test when you get there.

Penny_Farthing_2

Thanks in2deep. Tomorrow it's having the bits changed but then I'll take it back to the council MOT garage on Friday for the retest. I'll run it hard on the motorway first, though, with lots of revs.
If it fails the retest, will I have to start again from scratch do you know?

Night-owl_6

Quick fix advice, hammer the engine before taking it to the MOT test.
Bring the revs up to 6 revs on the counter and leave it for 5 minutes, you need the engine RED hot, makesure you have pently of water it in, then take it for a drive for around for about 20 minutes and hammer the engine 60 miles per hour and then drive to the test station, you then need them to test it within 20 minutes of the engine VERY hot, this will stop the smoke temp till the engine reachs its normal temp - I have done this and know people who have, it works!

goldspanners

Night-owl wrote: »

Quick fix advice, hammer the engine before taking it to the MOT test.
Bring the revs up to 6 revs on the counter and leave it for 5 minutes, you need the engine RED hot, makesure you have pently of water it in, then take it for a drive for around for about 20 minutes and hammer the engine 60 miles per hour and then drive to the test station, you then need them to test it within 20 minutes of the engine VERY hot, this will stop the smoke temp till the engine reachs its normal temp - I have done this and know people who have, it works!

6 revs? do you not mean 6000 rpm? if so i doubt this diesel engine will even reach 6000 rpm,5000 at very most.
5 mins is a long time at full revs,i wouldnt even do it in my works van.

Penny_Farthing_2

It freaks me too Goldspanners. I think the most I've done really is 2 or 3 minutes at 5000. Had all the bits done today, except the tyre. The guys also put a flush in. Etyres are fitting the tyre tomorrow then I'm taking it to the council for a retest, driving 20 miles from work to the centre so will have a nice hot engine when it gets there.
Wish me luck and thanks to all of you for the help.

Night-owl_6

I revved my old petrol escort upto 7000 rpm, admitingly the temp counter went right up to high but it passed the MOT

Pew_Pew_Pew_Lasers!

Alternatively instead of magic solutions for passing the MOT (which will only blow latent soot from the exhaust, nowhere else), I would suggest repairing the fault since it is undoubtedly leading to increased fuel consumption/reduced power.

jazzy

I would also suggest to take the car to a diesel specialist, it sounds like it could be a faulty egr valve? but that's only a guess?

Hotspur

While I was waiting to collect my Focus TDCi after a service there was a chap getting advice on what he should do when he brought his diesel car back for a retest. Yes, you guesed it, the advice was to take the car for a long 20 mile run at high (legal) speed on a motorway/dual carriageway to thoroughly warm the engine and in a gear suitable to keep the revs high enough (but not to thrash the engine) to blow any soot through the system.
Put the car through the test ASAP after the run.

gilbert_and_sullivan

And when you've got your car through the mot, get yourself some millers diesel power plus, or diesel power sport 4, and use regularly.

Lots of people will tell you this is just snake oil.
I've been using this stuff for donkeys years and been running diesel cars since about 84 and i've not had a fuel or fuel system problem yet.