diesel emission test - help!

Mothman · Post by **Mothman** » Fri Oct 15, 2010 8:09 pm

Another thought Tim,

as its been standing for a long time, the oil could have degraded a bit, also, may not have been changed for a long time anyway and could have diesel it it so a flush and change could not do any harm. I feed mine with synthetic[very cheap at Trago's[ and its going fine after 4 1/2 years of being deiven by me[sometimes thrashed too].

Andy

MULLEY · Post by **MULLEY** » Fri Oct 15, 2010 8:37 pm

Can old glowplugs affect the smoke test?

Way2go · Post by **Way2go** » Fri Oct 15, 2010 8:39 pm

MULLEY wrote:Can old glowplugs affect the smoke test?

Shouldn't think so as they're not in operation when the test is performed.

MULLEY · Post by **MULLEY** » Fri Oct 15, 2010 8:41 pm

That's what i initially was thinking, but i'm sure i read somewhere that glowplugs are kinda on all of the time?? Could have mis-read this of course? or is it modern diesels that do this?

Way2go · Post by **Way2go** » Fri Oct 15, 2010 8:48 pm

Newer ones have post-heating but they will be off shortly after the engine starts though.

MULLEY · Post by **MULLEY** » Fri Oct 15, 2010 8:57 pm

That sounds exactly like my thoughts were, i'm now going to have to try & find that article

to see what on earth it was about. At least that idea can be scrubbed from the list of possibles

richardd1652 · Post by **richardd1652** » Fri Oct 15, 2010 9:41 pm

If the MOT man says its diesel smoke and not oil burning then i think it could be over fuelling problems.We had a new VW Transporter which we decided to "chip up" from 130 to 170 bhp (just for a lauph at the traffic lights really) and it went like sh4t of a stick but kicked out a cloud of black smoke in the process.What colour is your smoke?I have also talked to my mechanic pal who told me about cutting them back on the pump in the first place,he uses a fuel additive all the time to clean the system prior to test and then if it doesnt work he then plays with the fuelling.I always thought that if they were burning engine oil then the smoke was blue?If its a knackered injector wouldnt it run rough?
Richard.

MULLEY · Post by **MULLEY** » Fri Oct 15, 2010 10:20 pm

If it was a knackered injector, i suppose it depends upon how bad it is, could just be a slightly poor spray pattern which may not actually be that apparent when driving, but could affect the emissions?

richardd1652 · Post by **richardd1652** » Fri Oct 15, 2010 10:25 pm

If its been stood so long ,could it be something more drastic like the H/gasket?Mind you that would be more than likely white smoke wouldnt it?
Richard.

MULLEY · Post by **MULLEY** » Fri Oct 15, 2010 11:36 pm

TBH i wouldn't be surprised if its old fuel, so syphon it out & change the fuel filter & i bet it then passes.....

richardd1652 · Post by **richardd1652** » Fri Oct 15, 2010 11:42 pm

Its worth trying before taking it to pieces?

Post by **docchevron** » Sat Oct 16, 2010 1:48 am

Doesn't need to burn oil for the oil to hav an effect on the emissions.
You'd be amazed at the difference between testing an engine with old oil, then immediatley retesting with fresh oil.

As it's NA it's most likely got the bosch pump, so a piece of piss to turn the fuelling down.
Injectors *could* be sticking, but frankly I've got utter dogs through the test by turning the pump down.
Remember that visible smoke and metered smoke aren't the same thing, so just because an engine black soots out the exhaust doesn't neccessarily mean it'll fail a test.

The test is bullshit anyway, ragging the tits off an engine off load does nothing meangingful at all really.

Gibbo2286 · Post by **Gibbo2286** » Sat Oct 16, 2010 9:28 am

You're all missing the most obvious cause which is pump timing, do it properly and you'll get a clean exhaust.

If you haven't got the necessary kit just advance the pump a degree at a time,

I know it's a pig to get at but all the other tricks are a waste of time until the timing's right. Gibbo.

tim · Post by **tim** » Sat Oct 16, 2010 4:52 pm

I changed the oil just now after giving the motor a burst of flushing agent, so it's now clean. The silencer is a Bosal, it may well be that a pattern type exhaust can give problems but unless someone can put a name to the good and the bad, it's too pricey to start swapping on spec - the system came on the car and is still surprisingly sound.
I also had a rootle in the back of the car and came up with some old paperwork, the thing passed its last MOT in 2007 and has done less than 300 miles since then. (All right after that last MOT). I can't think that someone has been fiddling with the pump (nor that the injectors have imploded in that short length of time)Which is a Bosch by the way. I was going to look at the fuel filter but please, someone, tell me where the f... it is! I have been lying on my back under the wagon with a good torch as according to the highly dodgy Haynes it's maybe to rear of the fuel tank but I can't see anything, I'm obviously looking in the wrong place.....

MULLEY · Post by **MULLEY** » Sat Oct 16, 2010 10:12 pm

The petrol engined cars have the fuel filter near the fuel tank, the diesels are in the engine bay, i think theres a few versions. Do you have any pictures of your engine bay that you could post up, we can then advise where it is, unless someone can accurately describe what they look like & whereabouts they are?