2.2 HDi 173 hp blowing smoke.

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jml
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2.2 HDi 173 hp blowing smoke.

Post by jml »

Recently, under hard acceleration, my C8 blows a very unpleasant cloud of smoke out of the exhaust.

As a bit of history, almost from new a smallish amount of oil has accumulated in the stainless steel pipe that goes under the engine from the turbos to the intake. I raised this with both a dealer and Citroen’s HQ and was assured that it was not unusual and not a cause for concern. My fears of one of the turbos having blown proved unfounded as it has now covered nearly 170,000 miles with virtually no problems.

However now I have this cloud of smoke under hard acceleration, I wonder whether this oil has progressively filled up the intercooler. The smoke seems to come from about 2000 rpm which is, loosely speaking, when the second turbo cuts in and I wonder whether the additional pressure from the 2nd turbo is blowing the oil in the intercooler into the inlet.

Has anybody else experienced similar or have any thoughts on the subject ?

All comments gratefully received !
jml
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Re: 2.2 HDi 173 hp blowing smoke.

Post by jml »

Bump !

Any thoughts on this ?

Has anybody experienced anything similar, even on different engines ?

Any comments or thoughts gratefully received

Cheers

Julian
electronmirror
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Re: 2.2 HDi 173 hp blowing smoke.

Post by electronmirror »

What colour smoke?
jml
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Re: 2.2 HDi 173 hp blowing smoke.

Post by jml »

Hi Ted,

Thanks for replying. The smoke is definitely black.

I overtook a slow moving bus this afternoon- and it’s amazing the kick you get as the second turbo kicks in - but I glanced behind me and there was the cloud ! I think it only happens for a second or two and as I carried on accelerating I’m pretty sure the smoke stopped.

Cheers

Julian
Hell Razor5543
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Re: 2.2 HDi 173 hp blowing smoke.

Post by Hell Razor5543 »

Black smoke usually means improperly burnt fuel, usually (but not always) because of a poor air supply. It couple be worth checking the air filter and the associated pipework. However, as the smoke is only visible for a second or so it is unlikely to be serious.
jml
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Re: 2.2 HDi 173 hp blowing smoke.

Post by jml »

Thanks James,

I’ll check the filter and pipe work, although there doesn’t appear to be any detrimental effect on power. It goes like a rocket when I want it to, although I usually drive more like Miss Daisy than Neil Armstrong !

Do you have any thoughts about my oil in intercooler/pipe work theory ?

Thanks for the reassurance of it not likely to be serious, although I do still wonder whether the oil may be coming from a leaky second turbo ?

Cheers

Julian
electronmirror
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Re: 2.2 HDi 173 hp blowing smoke.

Post by electronmirror »

If it's black smoke it is unburnt diesel.
If it's blue it would be engine oil ingested through the inlet manifold, passed by worn piston rings or knackered valve guides.
jml
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Re: 2.2 HDi 173 hp blowing smoke.

Post by jml »

Thanks Ted,

Good point about oil smoke being blue.

As I mentioned, it seems to be black smoke however I did a Diagbox test on the car and everything seemed ok.

Cheers

Julian
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Paul-R
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Re: 2.2 HDi 173 hp blowing smoke.

Post by Paul-R »

electronmirror wrote:
17 Sep 2021, 19:43
If it's blue it would be engine oil ingested through the inlet manifold, passed by worn piston rings or knackered valve guides.
Less likely to happen on engines with forced induction as the pressure tends to blow the oil back upwards rather than sucking it down on non-turbo engines.
Hell Razor5543
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Re: 2.2 HDi 173 hp blowing smoke.

Post by Hell Razor5543 »

Just a thought. At the point where the steel pipe (to the intercooler from the turbo) connects to the 'rubber' pipe there may be two clips; a retaining clip to stop the two pipes separating and a jubilee clip to make an airtight seal. When my C5 (with the same engine) developed a problem I found that the jubilee clip was no longer there, so some of the air was escaping at that union. While my C5 is still off the road (bigger problem) I would hope that fitting a 50-70mm jubilee clip (size 3) with help with the performance slightly, as well as improve the emissions (less black smoke under acceleration).
jml
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Re: 2.2 HDi 173 hp blowing smoke.

Post by jml »

Thanks James,

That’s a good point and I’ll check that out.

Cheers

Julian