Hi guys I have a cr170 on a 58 plate. Recently my car every now and then will start to idle at 900 rpm and when I set off kicks out blue smoke from exhaust. Some times I see smoke coming from the bonnet. Inspected it and it smelt like oil burning coming from underneath the turbo area. Took it to my local and he advised me that it was the return pipe from the turbo to the sump that had a small oil leak. 6 months ago I had a recon turbo fitted and my oil pump and bottom half of my engine done as my oil pump packed in and caused my turbo to blow and damaged the engine. My question is if there is an oil leak from the return pipe how is it that my exhaust would blow blue smoke. Sometimes I'll drive it with the problem and then suddenly when I stop at some lights the revs would go back to normal and the problem would be gone no smoke what so ever. It is now a daily problem. Will start up fine and an hour or 2 later would start to play up and then 10 mins later it's fine again. Any advise is welcome guys.

If the blue smoke appears as you drive off it could be the smoke simply coming through from under the bonnet as you pull away.

No it's clearly visible coming from the left side where the exhaust is. Had the return pipes changed yesterday and no more oil leak but the problems come back this morning clouds of blue smoke from exhaust.

Well if it was not there before the turbo work then I would think that a turbo seal to the intake side is passing oil.

Can an air leak cause rough idle and blue smoke?

Had the AA out today when the problem started. As soon as the AA driver got to me he walked over and asked if it smoked when I revved which I replied yes. He gave it a Rev and no blue smoke and idle went to normal level. Luckily enough he had seen the high idle before he revved and also heard the unusual engine noise. No faults came up on his obd reader. Checked oil level and said it is high. Drained oil to correct level. There had been a 1 extra litre in engine. He advised me that this could have been the most likely cause and if it started to play up again it could well be a faulty injector.

Or it has been trying to do DPF regen and keeps getting interrupted during process and sump is filling up with Deisel.

Get the oil checked and see if you can smell deisel in it 

If so get it changed 

My wifes Meriva used to do this due to not getting a long enough run 

The distance she would travel to work was long enough to start  the process but just not long enough to complete it so it would try again the next time ......Filling the sump with deisel

But with a dpf regen wouldn't the dpf light come on?

No.

You hardly know the car is doing it but a slight change in revs that I have found.

Seems really stupid as if it did have a light you would be able to go for a good drive and let it finish.

Have seen some cars wreck engines as the oil level gets so high it feeds back into engine and you have a run away syndrome. (Not nice)

Like this https://www.youtube.com/watch?v=LbcN6EYVs1E

Edited 23 March, 201610 yr by DEL80Y

You hardly know the car is doing it but a slight change in revs that I have found.

Seems really stupid as if it did have a light you would be able to go for a good drive and let it finish.

Have seen some cars wreck engines as the oil level gets so high it feeds back into engine and you have a run away syndrome. (Not nice)

Like this https://www.youtube.com/watch?v=LbcN6EYVs1E

 

Runaways like that are usually due to failure of the seals in the turbocharger - the oil gets through into the air intake and the engine runs off it until it dies. There's little reason for diesel to get into the oil from a DPF regen - the main change during regen is that injection/ignition timing is adjusted to increase exhaust temperatures and drive up NOx emissions (the NOx is then used to oxidise the soot in the DPF).

Runaways like that are usually due to failure of the seals in the turbocharger - the oil gets through into the air intake and the engine runs off it until it dies. There's little reason for diesel to get into the oil from a DPF regen - the main change during regen is that injection/ignition timing is adjusted to increase exhaust temperatures and drive up NOx emissions (the NOx is then used to oxidise the soot in the DPF).

Wrong about the above

I have to take the wifes Meriva on along drive each week because the drive to her works is just enough to start the regeneration but never long enough to finish so it keeps reseting and filling sump with oil,

From the AA website

If the regeneration is unsuccessful due to an insufficient driving cycle the extra fuel injected into the cylinders will not burn and will drain into the sump.  As a result, oil quality will deteriorate and the level will rise.  Most DPF equipped engines will have an oil quality/viscosity sensor but it is important that you check that the oil level does not increase above the maximum level on the dipstick as diesel engines can run on their own oil if the level is excessive – often to the point of destruction.

http://www.theaa.com/motoring_advice/fuels-and-environment/diesel-particulate-filters.html

Edited 23 March, 201610 yr by DEL80Y

i would say this is a crankcase breather dropping some oil into the air intake pipe, and it hits you turbo when you start it up, and burns it off.

 

I had exactly the same thing on an older TDI and had to do the elephant mod to stop it sucking it through on start.

 

I would therefore check your crankcase breather and pipework is not full of oil or something.

Runaways like that are usually due to failure of the seals in the turbocharger - the oil gets through into the air intake and the engine runs off it until it dies. There's little reason for diesel to get into the oil from a DPF regen - the main change during regen is that injection/ignition timing is adjusted to increase exhaust temperatures and drive up NOx emissions (the NOx is then used to oxidise the soot in the DPF).

 

There are two major causes of diesel engine runnaway:-

 

1)If Turbo oil seals fail on the inlet side oil can be fed into the engine along with air/oxygen - in the right circumstances the engine can run on this alone - result = bang unless you can stall the engine

 

2)Some DPF implementations are poor, especially early ones where they can be prone to engine runaway where diesel has overfilled and diluted the engine sump oil during numerous regen injection cycles designed to push diesel down the exhaust - but some can run down the bores especially when pistons/rings start wearing. Diesel is also a poor lubricant so a side effect is engine wear (bores due to diesel running down them and the rest of the engine due to sump oil contamination). Early diesel Zafiras are prone to this!

Early DPF implementations were a bit of a bodge / add on where the filter is installed further down the exhaust(cooler) where passive regens are unlikely. Later implementations much better where the filter is close coupled with the engine

Edited 3 April, 201610 yr by bigjohn