Clouds of thick grey smoke

George · Unread post by **George** » 06 Jun 2009, 18:49

T-reg Xantia est 1.9TD Bosch pump

Starts and drives fine, maybe for ten minutes, maybe for half an hour. Then starts to mis-fire with clouds of thick grey smoke and stalls. Maybe then it decides to re-start at once or after half an hour or so and repeats this cycle.

I took a look at the fuel filter and all was well but changed it anyway, fuel is clean.

I'm thinking it's the pump and have a replacement ready. But first wondered how some of you guys would go about diagnosing this one?

I would be gratefull for any help and suggestions!

MikeT · Unread post by **MikeT** » 06 Jun 2009, 20:21

White smoke from a diesel indicates unburnt (boiled I think) fuel and for that to suddenly start on a warmed up engine is puzzling as I've come to only expect white smoke on initial startup when the cylinders don't get hot enough to ignite the fuel. Once they start, diesels should have plenty of heat to continue running until you stop the fuel (turn off the engine, therefore the pump). So after all that, I don't know what to guess it could be. Perhaps an intermittent injector spray pattern dumping too large drops of fuel?

Unread post by **Peter.N.** » 06 Jun 2009, 20:31

The colour of the smoke is really the indicator, you say grey smoke, is this light or dark grey? If its dark grey verging on black it could well be air starvation due possibly to a collapsing hose in the air intake system.

Try disconnecting the air hose from the inlet manifold, you will lose your turbo boost but also any possible restriction, give it a good work out and see what happens.

MikeT · Unread post by **MikeT** » 07 Jun 2009, 11:37

Peter.N. wrote:If its dark grey verging on black

Ah, yes, that makes perfect sense!

George · Unread post by **George** » 07 Jun 2009, 12:16

Peter.N. wrote:The colour of the smoke is really the indicator, you say grey smoke, is this light or dark grey? If its dark grey verging on black it could well be air starvation due possibly to a collapsing hose in the air intake system.

Try disconnecting the air hose from the inlet manifold, you will lose your turbo boost but also any possible restriction, give it a good work out and see what happens.

Thank's that's cheered me up no end!

Yes it's dark grey verging on black, I did check the air filter as a matter of course which was clean, but didn't check further.

As the car is parked up ten miles away, I won't be able to check until tuesday or wednesday.

I hope you're right as this car's been hanging about for some considerable time, as I've not been looking forward to this job.

dieseldoggy · Unread post by **dieseldoggy** » 10 Jun 2009, 01:41

try the EGR valve and associated componets.as if it is stuck open or circuit of bits fail it will give you that problem.done one on a pug 206 non turbo it was gummed up and threw out alsortsa s**t

Unread post by **Peter.N.** » 10 Jun 2009, 12:18

That's possible as well. I keep forgetting about EGR on 1.9 XUD's as I have never had one with it.

jgra1 · Unread post by **jgra1** » 10 Jun 2009, 12:36

I did get this once when a turbo failed.. 405 estate

I dont know why it was grey, maybe it was partially burnt.? but it seemed grey and there were clouds of it...

of course the oil soon ran out

but got home fine with more oil and bolted a new turbo and all fine

dieseldoggy · Unread post by **dieseldoggy** » 10 Jun 2009, 16:07

Peter.N. wrote:That's possible as well. I keep forgetting about EGR on 1.9 XUD's as I have never had one with it.

whats the 1.9td like pre ecu?are they any better or not? ie fuel and power.had a 94 m reg rattled better than a tommy gun on full tilt? but did go and recconed about 60 mpg on a run near 700 to a tank but i can eeek great fuel returns out of most things. xreg 82 1.8 datsun B'bird est 4speed had 50 odd mpg on a long trip in the midd 80's £8.80 in petrol 212 miles.those where the days?

Xaccers · Unread post by **Xaccers** » 10 Jun 2009, 16:44

dieseldoggy wrote:
Peter.N. wrote:That's possible as well. I keep forgetting about EGR on 1.9 XUD's as I have never had one with it.
whats the 1.9td like pre ecu?are they any better or not? ie fuel and power.had a 94 m reg rattled better than a tommy gun on full tilt? but did go and recconed about 60 mpg on a run near 700 to a tank but i can eeek great fuel returns out of most things. xreg 82 1.8 datsun B'bird est 4speed had 50 odd mpg on a long trip in the midd 80's £8.80 in petrol 212 miles.those where the days?

My N reg first Xantia did 816miles on a single tank once.
Used to go like a rocket too.
Teh_Agent's engine was fitted with a mechanical pump while his was repaired and it gave it more oomph too.

Unread post by **Peter.N.** » 10 Jun 2009, 20:22

I don't think electronic control is much of an improvment over a good mechanical pump. All the XM's I have had mechanical pumps, in fact I have three all registered in Jan 96, the last ones with mechanical fuel injection and almost the last manuals.

The 2.1 engine is a much improved version of the 1.9 with 12 valves and a redesigned cooling system which helps prevent the heads from cracking, they are capable of 50 mpg + in a car weighing over one and a half tons, the Xantial and 406 uses an electronic fly by wire version but I din't think the fuel consumption is appreciably better, maybe one or two mpg but the injection system is certainly not as durable.