Grey smoke from exhaust at 20K

[showard8]

Hi,

Seems my Volvo is cursed, now the suspension knocking noise is gone i've a new issue.

The wife set off earlier to the supermarket, she got 4 miles from home and I got a phone call saying that the XC70 was putting out vast quantities of grey smoke and it smelt like burning...... she limpt it home at 30 MPH covering the queue behind in smoke, she reversed onto the drive and could barely see out the rear window. it did stop smoking and then recommence on the way back....

She said it drove normally, no power loss, no warning lights, nothing.

I came home at lunch, checked coolant, engine oil, all normal, started car, no abnormal noises, no smoke, drove it.. hard for 30 mins, no smoke, got underneath, no oil leaks, nothing.

I cant get it to do it again but its clearly not common practice.

Any ideas anyone?....
She said it smelt like oil..... Its a 2009 XC70 with 20k on the clock

[tt82]

What engine is it?

My initial impression is it's a diesel and that was a DPF regeneration (though a warning should come up on the dash). 20k on a diesel engine, especially a modern diesel engine with DPF isn't good. Ideally you need to be doing more miles or make sure you periodically take the car for a good thrash to clear out the DPF.

Now that it's cleared the symptoms won't show again untill the DPf becomes full again.

[showard8]

Hi, Its a D5 diesel 2.4 I've only had it 2 months and done 3K in it, forgive my ignorance but what is a DPF regeneration?

The car gets 'Driven' overtaking and such like but not redlined and hammered.

[tt82]

Read this - http://www.volvocars.com/uk/sales-se...te-filter.aspx

What is your likely annual mileage to be in this car? If your not gonna be doing 10K + then you would really be better off with a petrol.

[showard8]

Annual mileage will be roughly 12-15K, I've only just got the car -3 months ago and it was a disability lease car before that, hence the low miles.

I'll make sure I pop it in manual mode and sit at 3000 rpm for 20 mins or so later on the motorway to get it hot, but the wife says the smoke was defiantly not black, as it would be if it was diesel, it was a white / grey bellowing from the exhaust.

[tt82]

Well the idea of the DPF is to remove all the black smoke, aka as the Diesel Particles (did you read the link?). I must confess I've never seen a DPF regeneration to know what happens, if there is smoke, loss of power, etc. Maybe a member who has could post their experience.

The only other reason I can think of for white smoke is coolant being burnt off. Might be worth checking you coolant level just in case.

I wouldn't bother taking it back out again, what you've done already should have been enough to get the DPF up to temp. Basically from what I've read about DPF's is that the main thing is heat. They need heat to burn off the soot or they fill up, hence why it's placed so close to the engine as this is where the exhaust will be hottest. Any good run, either in distance or length should be enough to get everything fully up to temp. My guess would be about 20 miles or 30-45 minutes of constant running will be sufficient. The problems occur when you only pop the 1 mile to the shops and never use the car more than 5 or 10 minutes.

[showard8]

Hi,

The car is in daily use on a 60 min round commute with most of it on open roads at 60 mph, its not hammered but is not driven slowly, it is well up to operating temperature.

I hope it is something like this and not anything more terminal..

[Backhill1]

It's possible you have a sticking egr valve. Normally egr issues or Maf show an engine system service indication and a yellow triangle.
The Volvo diagnostic system appears to be good and without an alarm I think you might be loosing boost collapsed hose / intercooler etc / egr all will give excess smoke. I have never experienced loss of power or excess smoke during re-gen just high consumption.

[clivea]

Volvo's link is interesting as it says that for the DPFs that don't require an additive to regenerate the DPF lasts the lifetime of the car. I'd read that even this type of DPF cannot completely remove the ash residue left when the DPF regenerates, and therefore you will get a slow build up of ash which eventually requires a DPF replacement. The advice was to use branded premium diesel as it has a quarter of the ash content of supermarket fuels. Hence lengthening the period between replacement.

It would be interesting to hear what mileages have now been logged by DPF fitted D5s. Mines done 34k in 3 years but she doesn't get used for short trips, and hauls a caravan too. But there are times I have to take it for a run as it may not have been used for a week or more.

[tt82]

Hi clive

Thats one of the reasons I started the Whats your mileage? thread. As for DPF's, my theory on my understanding of how it works is that occoasional non use is fine and you don't need to take it out for a run just because it's been stood for a week.

An engine is at it's worst when first starting up, remember how Castrol tell us that most engine wear occurs after starting. Untill the engine is up to temp it doesn't run properly. At this point you will be using a lot of fuel and creating a lot of soot/Diesel Particles and the DPF is not yet at the required temp to burn it all off. If you switch off the engine before the DPF reaches operating temp then the soot will remain and more soot will be added the next time you start up. Repeating this constantly will lead to the DPF filling up and a regeneration being required, although any substantial journey should get the DPF hot enough to burn it all off.

In your case, not using the car means no soot is being formed in the DPF and there is nothing that needs to be burned off. As long as when you do use the car it isn't for lots of short journeys where the engine is allowed to cool inbetween, then you should be ok.

Note: This is just my opinion, it may be wrong but thats what I believe.