Polo 1.4 TDi - Smoking

[tjdixon911]

I have a 2008 Polo 1.4 TDi, I have noticed (in my rear view) smoke out the rear. This is only noticeable at around 60-70 whilst accelerating - whilst stationary no smoke is visible from the rear, I guess its something under the engine bay that is being blown out as driven, through normal town driving it doesn't appear to happen.

Any ideas what this might be?

My thoughts are;

I'm guessing not the Head Gasket as smoke would be visible all the time.
Could it be a Turbo issue? (There doesn't seem to be a drop in performance).
Or a split hose somewhere that's just leaking onto the exhaust and burning off (I had a split fuel line previously that stunk of diesel)
Any thing else I should check?

The car has done 116k.

Thanks

Tom

[Steve_D]

What colour is the smoke.

Blue would not be good.

Steve

[tjdixon911]

It appears to be White Smoke, its difficult to tell as its always dark when I'm driving it at the moment.

I will have a look under the bonnet tonight, see if I can see anything obvious..

[tjdixon911]

There is nothing obvious under the bonnet, I had a drive with the window down to have a listen the turbo seems a little noisy, not the usual whistle you'd expect...I may just be paranoid!

[Locknut]

Does this happen every time you accelerate at 60 or 70MPH? If it's only occasional and it happens only with a well-warmed engine, it could be the particulate filter regenerating. This would be normal. If it happens all the time you have a genuine smoke problem. The easiest thing to check is the air filter which could be dirty. Next on the list of suspects would be timing but that's not so easily checked.

[powerstroke]

powerstroke said:

tjdixon911 said:

It appears to be White Smoke, its difficult to tell as its always dark when I'm driving it at the moment.

I will have a look under the bonnet tonight, see if I can see anything obvious..

some times with a higher mileage diesel there is a little haze that's only visible in the
Mirror at night , I would check the air filter and the turbo pipe work , but sadly the manufactures optimistically
long service intervals really start to take there toll as the mileage goes over the 100k mark with turbo and engine
Wear,good for the first owner and the manufacturer not so good for the second and subsiquent owners!!
Realy to get the longest life you need to be changing oil at about 6k
Unless the oil in yours looks really clean I would change it run it for a few hundred miles
And change again to really flush out any sludge and carbon.. Then every 6 k ,don't worry too much unless there is blue or white smoke all the time black which then clears when you give it a bit of stick especially after town or gentle driving is quite normal..

[tjdixon911]

It seems to be happening most of the time while accelerating between 60 and 70 (maybe slightly less today), it'll then happen occasionally after a motorway run (off roundabouts etc).

I'll have a look at the air filter later...

How long can the particulate filters take to regenerate?

My service intervals are 10k as standard, the current oil is about 4-5k old (a couple of months!) but is quite black when I checked yesterday.

[Locknut]

tjdixon911 said:

How long can the particulate filters take to regenerate?

Here's an article on the subject:
http://www.remmington.info/DPFfilters.html

And here's a quote from the same article that deals with your question:

Remington said:

Question: How long does complete regeneration take? a.) In the most favourable case? b.) In the least favourable case?

Answer: a.) Under constant conditions, i.e. the exhaust temperature necessary for regeneration always lies above the required value, for example during motorway/cross-country driving, the average regeneration time is 10 minutes.

b.) Vehicle conditions such as long down-hill descents, frequent driving in the low-load range (city driving, idling) allow the exhaust temperature to fall. If the conditions for triggering regeneration were fulfilled, the active regeneration time can be extended up to 25 minutes (depending on engine type). If complete regeneration is not possible within this period, the regeneration will be interrupted.

I am now doubtful that you are having a regeneration.

[tjdixon911]

Locknut said:

Here's an article on the subject:
http://www.remmington.info/DPFfilters.html

And here's a quote from the same article that deals with your question:

Remington said:

Question: How long does complete regeneration take? a.) In the most favourable case? b.) In the least favourable case?

Answer: a.) Under constant conditions, i.e. the exhaust temperature necessary for regeneration always lies above the required value, for example during motorway/cross-country driving, the average regeneration time is 10 minutes.

b.) Vehicle conditions such as long down-hill descents, frequent driving in the low-load range (city driving, idling) allow the exhaust temperature to fall. If the conditions for triggering regeneration were fulfilled, the active regeneration time can be extended up to 25 minutes (depending on engine type). If complete regeneration is not possible within this period, the regeneration will be interrupted.

I am now doubtful that you are having a regeneration.

Yeah, that does sound doubtful..

[bearman68]

A split turbo hose would give a black smoke, though would give a drop off in performance as well. It often gives a 'popping' noise, as the crack opens up once the pressure is sufficient.
It might also be a lower than ideal fuel pressure or poor injection pattern. I would be tempted to chuck in a can of injector cleaner. Forte make some of the best stuff, at about £20 a treatment.
One other thing that springs to mind is an EGR valve issue. A sticking EGR will produce white smoke, and will often cause the engine to run rough and lumpy at certain times.
EGR valve will require a clean as a first action. It might be worth stripping off the inlet manifold and cleaning out the manky stuff that will undoubtedly be accumulated in there.

[tjdixon911]

bearman68 said:

A split turbo hose would give a black smoke, though would give a drop off in performance as well. It often gives a 'popping' noise, as the crack opens up once the pressure is sufficient.
It might also be a lower than ideal fuel pressure or poor injection pattern. I would be tempted to chuck in a can of injector cleaner. Forte make some of the best stuff, at about £20 a treatment.
One other thing that springs to mind is an EGR valve issue. A sticking EGR will produce white smoke, and will often cause the engine to run rough and lumpy at certain times.
EGR valve will require a clean as a first action. It might be worth stripping off the inlet manifold and cleaning out the manky stuff that will undoubtedly be accumulated in there.

Thanks, I may try some injector cleaner next and have a clean of the EGR valve (if I can find it!)

There doesn't appear to be any drop in performance, and its not running rough / lumpy.

I've just taken a look at the Air Filter and it looks pretty good, I had the engine running and had a good look around and there are no obvious split hoses/leaks, gave it a good rev (annoying the neighbors at this hour!) and there was no smoke to be seen....

[powerstroke]

tjdixon911 said:

It seems to be happening most of the time while accelerating between 60 and 70 (maybe slightly less today), it'll then happen occasionally after a motorway run (off roundabouts etc).

I'll have a look at the air filter later...

How long can the particulate filters take to regenerate?

My service intervals are 10k as standard, the current oil is about 4-5k old (a couple of months!) but is quite black when I checked yesterday.

To be honest if it runs ok ,fuel consumption about expected and not smoking all the Time
I wouldn't worry to much .., just keep up with maintenance clean oil and filters etc,,,

[Locknut]

tjdixon911 said:

I've just taken a look at the Air Filter and it looks pretty good...

Just one slightly pedantic question and I hope you don't think I'm underestimating your ability: Did you take out the filter element to examine it? The dirty side is always turned down and the top side generally looks clean so you need to take it out to examine it properly.

[tjdixon911]

Locknut said:

Just one slightly pedantic question and I hope you don't think I'm underestimating your ability: Did you take out the filter element to examine it? The dirty side is always turned down and the top side generally looks clean so you need to take it out to examine it properly.

When it comes to engines my ability is pretty poor so sometimes I need the obvious pointing out to me, I did however on this occasion do something right and checked the whole filter

[tjdixon911]

This morning I have taken the pipework off the EGR valve and given it a clean out inside (mainly oil?) didn't take the unit off so cleaned what I could whilst still attached to the car. the valve seemed to be moving ok, a little resistance against the motor/solenoid...

Also put some injector cleaner in (doubt this will make much difference straight away) and gave it a run (first run in daylight since noticing the issue) and apart from a little black smoke once, I couldn't see any smoke at all.. I guess a night run will be needed.

[Locknut]

tjdixon911 said:

... I couldn't see any smoke at all.. I guess a night run will be needed.

Are you only seeing this at night? Are you seeing it in the lights of the cars behind you? Is the road damp?

A damp road (as distinct from a wet road) can give just enough spray to look like smoke in the lights of the cars behind. You're better off testing in daylight.

[tjdixon911]

Locknut said:

Are you only seeing this at night? Are you seeing it in the lights of the cars behind you? Is the road damp?

A damp road (as distinct from a wet road) can give just enough spray to look like smoke in the lights of the cars behind. You're better off testing in daylight.

It's only visible at night no matter if the road is dry or not, and only smokes when I put my foot down.

I had my other half following me last night, she said the smoke was coming from the exhaust and stunk/tasted funny (had her window open), couldn't explain what of though...

[tjdixon911]

I've had a new development on this.

I am now suffering loss of Power as if the turbo has cut out, it will still run and (just about) get to 70 but will noticeably slow down on uphills etc. this has happened a couple of times.

Switching the engine off and back on again (when safe) so far has bought it back to life...

There seems to be less smoke when the power drops.

ETA it's now booked in to let someone who knows what their doing take a look.

[bearman68]

Sounds more and more like a sticking EGR to me.

Keep up the posts, following with interest.

Good luck

[tjdixon911]

bearman68 said:

Sounds more and more like a sticking EGR to me.

Keep up the posts, following with interest.

Good luck

From what's been said above I think that may be the case, I've noticed a little bit of lumpy running recently. If it is the EGR will this get picked up by the diagnostics? I don't want to end up chasing the problem and spending fortunes on the car..