diesel emissions MOT failure

When my Rover was smoking before the MOT I did the following after advice from a mechanic friend.

1. Replace cambelt. I had no indication whether this had been done so I thought it a good idea anyway - the belt was only about £15.
2. Change oil for a _good quality_ diesel oil - I used Castrol GTD in this case.

1. Add Wynn's StopSmoke _oil_ additive. Asda sell it cheap. It works.

These measures worked for me; the car used to smoke visibly before, but never did after, and it passed the MOT no trouble.

Beyond that you may be looking at reconditioning the injectors.

neat injector cleaner in the fuel filter does work, we've done it on various occasions with success, but looking at your readings id say your looking at injectors, thats a very high average !

If that's the actual result, then there's something quite amiss.

Is the air filter clean?

First option is to give the car a gold old italian tune up (make sure the cambelt isn't overdue replacement, and give it a good run to warm it up, then floor it, hitting the rev limiter in all the lower gears). If it doesn't get noticeably better after that, then there's something wrong with the fuel system (pump timing, excess fuel device on the pump for boost (can't remember it's proper name at the moment), injectors.....)

If those readings were done when the engine was hot then you need it looked at, injection cleaner will not reduce them enough and revving the tit's of it may do damage. You need the pump adjusted by someone who knows how and has the equipment to test the result.

beside the air box there should be a small yellow vaccum filter about the size of a 10p peice (a carnt remember wot its called)but i know it does something with the emmisions and should be changed every service but often overlooked.i think this vaccum filter works the EGR valve . also as mentioned before make sure air filter is clean, roadtest down a motorway then retest

"Fred"

Hmmm. Prevention rather than cure, that.

I've used several, all to good effect.

It'll burn it.

Yes, but this engine will burn a lot of things as well or instead as diesel. ;)

With all things, perhaps.

You have to drive the car. Preferably hard. No, drive it hard. Search for the governor in the lower three, maybe four gears. Find a long steep hill, load the car up, drive up it as fast as it'll go.

Yes.

Not worth it.

You need to load the engine up, so high load and high engine speed. To be fair running it up to 4,000 rpm ought to do well, but it's only another

The above assumes the engine and belts are in good mechanical health.

Okay, lots of points to consider but I'll stick with one: injector cleaner.

Injector clean does work, in your case it did what it was designed to do - clears the crud from the injectors... right into the exhaust, so that the exhaust gasses are dirty and the injectors are cleaning.

I'd recommend you run diesel clean in the tank or two *before* the MOT and run it on ordinary diesel for the test.

And as others have said, give it a good run pre-test. I lived a couple of hours from my preferred MOT station, bit extreme but my Mum lives in the same village, so my diesels always had a good run before hand. :)

Thanks to all those who replied, I'll try out the ideas and report back in a week or so with the MOT result!

:O)

Just another thought, A friends Avensis failed on high emmissions last year, with a bit of work, diesel treatment (italian tune-up!) it was lowered enough to pass..(just!) The clutch was done the other day and I noticed it was smoking again, It was coming back in for a timing belt change, Replaced the belt, and bingo, no smoke..

The old belt was a little bit slack, but as the Toyota has no means of locking the crank, pump etc, you have to get all the marks right I wondered if the belt being slack or timing being out just a little, was causing the high emmissions.

Des

After you have done as suggested here, run the vehicle around for a while in lower gears (not 1st gear done blow the thing up more like 4th)

Fluke