L300 Delica Diesel roughness and smoke on start-up

[fuel]

Hey guys,

I have a 1991 Delica Star Wagon (L300) P35W model (2.5 turbo diesel crystal lite roof) which has started to run rough and smoke white/blue smoke on start up until it starts to warm up after a few minutes. I made a video showing the smoke on start-up here - http://www.youtube.com/watch?v=n8hYe4FUFCo

It seems it only does it when left idling, as when you give it revs and hold it at revs (as in the 2nd half of the video) it doesn't smoke at all, except when it misfires (also in the video).

It doesn't use any oil or coolant and once it warms up it doesn't smoke at all and idles very well. I measured the resistance of each glow-plug at approx 1 ohm, but the resistance would slowly drop to about 0.8 ohm the longer I held the multimeter on them.

Also regarding the idle speed when cold, how can this be adjusted? It seems to idle at 800rpm regardless if its cold or warm, although sometimes when it's warm the idle revs will creep up to 1100rpm but when you briefly let the clutch out a bit with it in gear and brakes on to slow the engine down the revs will sit back at 800rpm again.

If it makes any difference, the timing belt and water pump have been replaced along with the injector pump being overhauled within the last 20,000kms.

This is my first diesel vehicle and I wouldn't even know where to start looking!

Thanks guys

-Phil in New Zealand

[norisan]

I'm thinking it may be time to have the injectors cleaned. I had a similar problem, but after replacing the injectors, no more smoke and virtually no roughness - also it has a lot more power.

[fuel]

ahh yeah I was wondering if maybe one or more of the injectors were dribbling - but I'm really not familiar with diesels so didn't know for sure.

It looks quite tricky to remove the injectors?

[marsgal42]

I've seen worse.

That's a little rough and a little smokey, but these are old-school diesels, and some smoke is to be expected.

I assume you are using correct starting procedure for the outside temperature? You can't just twist the key and go in the winter.

...laura

[fuel]

yes some smoke is to be expected.. but this is a smoke screen and it easily covers the driveway with smoke and wafts down the driveway, it's definitely not a normal amount of smoke for sure.

and yes I let the glow plug circuit do its thing before I start the engine, if I don't let the glow plugs warm up the engine will just keep cranking and not fire.

it's the beginning of spring here in New Zealand, we're already seeing temperatures of 20C so cold temperature is not at fault.

[Meanman]

does it smoke heavily when pulling away from a stop or when under hard acceleration or going up a hill? Possible Fuel pressure adjustment could help remedy, or IP service.

[fuel]

nope not that I know of - it does sometimes hesitate when pulling away from a stop but it doesn't do it very often. it smokes about the same amount as the typical diesel when you accelerate briskly.

[Green1]

quick run-down on smoke...
- white smoke: too little fuel (or too much water)
- blue smoke: burning oil
- black smoke: too much fuel (or too little air)

As you said you are not using any coolant or oil, most likely you have the "too little fuel" situation, things to look at for this are the injectors, fuel filter, and injection pump.
The easiest one to deal with is the fuel filter, change it. beyond that, getting the injectors cleaned and injection pump checked is not entirely a bad idea.

Next, idle control. 800rpm is rather high, most small diesels I have ever seen idle around 666rpm (ok, it's not that exact, it's more like a range of about 650-700 but it's amazing how many sit quite close to or right on that number)

To adjust the idle there are a couple things to look at, first of all by your left knee on pre-1994 L300s there is a throttle control, make sure it is not in use by turning it counter clockwise and releasing it. if it was already that way, then check the throttle-stop adjustment in the engine compartment. To do this open the engine compartment and watch what moves when you press the accelerator, then when you release the accelerator you can see the bolt that the mechanism rests against, adjust that bolt to adjust your idle speed.

[fuel]

Thanks for that!

It does smoke black smoke when accelerating heavily or going up-hill, which is pretty normal for diesels I gather - am just wondering how it going be supplying too little fuel when idling while it's able to over supply fuel at full throttle.

I will definitely replace the fuel filter and run a bottle or two of injector cleaner through the system anyway. I can get reconditioned injectors for about $350NZD on exchange with my existing injectors.

The idle control speed knob is definitely turned counterclockwise and not activated, so will look into adjusting the throttle-stop screw.

[Green1]

It does smoke black smoke when accelerating heavily or going up-hill, which is pretty normal for diesels I gather - am just wondering how it going be supplying too little fuel when idling while it's able to over supply fuel at full throttle.

not entirely uncommon... diesels will smoke under load... also under load they will blow out any built up deposits that are in the engine.

Another thing worth checking is the injection pump itself, cleaning it out can solve a lot of this sort of problem as well.

[Modsqwad]

Have you checked compression yet? As the motor heats up a bad hole can stop missing run smoother and make the white smoke
disappear. Also in the words of my old fuel injection teacher Olev Konismaw used to say with a heavy Ukrainian accent "most likely
a pissing nozzell " or in english a bad injector. Hope its not compression. Good luck.
Andy Wilson