Major Smoke issue

[Scvrs2]

Hi, I have a 2007 Pd105 Golf estate with 89k on the clock. It's been regularly serviced and maintained. Recently I've had a light grey/blue smoke issue which has slowly got worse. I've used vag-com and can't see any issues. I've changed the air filter and oil filter just in case either was clogged. When I unplug the MAF the smoke goes away, so I replaced the MAF with a new bosch one and the smoke came back straight away! It's also burning oil at a much faster rate than usual! On vag-com I've checked fuel temperature, coolant temperature, boost pressure, air intake stays and injector quantity and all seems to be OK, although I'm not expert! Is there anything else that anyone can please suggest before I keep throwing unnecessary time and money at trying things without success? Thanks in advance

[Warrior193]

Hello, S, not sure why the smoke stops when the MAF is unplugged - but from your description, it seems that your engine is burning lubricating oil. This could be due to worn piston rings or valve guides, but I would not expect that much wear at your mileage - are you sure of mileage history?

Another thing could be PCV valve - which could fit with the symptoms - but high oil use from excessive crankcase pressure would still indicate worn or broken piston rings. 

How much oil is it using per 1000 miles?

Edited 21 January, 2023 by Warrior193
Query

[Scvrs2]

Thanks for the reply, I'm 100% sure on the history of the car as its been in the family since new. I was also thinking it could be a blocked PCV/CCV or even a blocked/stuck egr valve. I pulled the breather hose from the rocker cover and it was spitting oil through it, not sure if that's supposed to happen or not. 

[Warrior193]

4 minutes ago, Scvrs2 said:

Thanks for the reply, I'm 100% sure on the history of the car as its been in the family since new. I was also thinking it could be a blocked PCV/CCV or even a blocked/stuck egr valve. I pulled the breather hose from the rocker cover and it was spitting oil through it, not sure if that's supposed to happen or not. 

Good morning, no, it definitely shouldn't be spitting oil from the breather hose! I fear that damaged piston or worn/broken rings are the cause - at your mileage, depending on time scale this issue appeared, I suspect damage or failure rather than wear 😭 Unfortunately, the only way of verifying this would be an engine strip down.

[Warrior193]

A compression check would help identify the cylinder at fault, but fixing the problem is likely to be uneconomic 😢

[Warrior193]

A thought just occurred to me, as you have a PD, have you checked the smell of the oil on the dipstick? Does it smell strongly of diesel? - if so, it might be a faulty fuel injector leaking fuel into one or more cylinders and down into the sump, which then raise the oil level to the point where it blows out of the sump from overpressure - but this would normally also be associated with difficult starting and a lot of black smoke on start.  

Edited 21 January, 2023 by Warrior193
correction

[Scvrs2]

I get no black smoke at all. Hopefully it's not beyond economical repair,fingers crossed. But why would this issue dissappear when the maf is disconnected, does that make sense to you? 

[Warrior193]

1 hour ago, Scvrs2 said:

I get no black smoke at all. Hopefully it's not beyond economical repair,fingers crossed. But why would this issue dissappear when the maf is disconnected, does that make sense to you? 

The only thing I can think of is that perhaps disconnecting the MAF is temporarily shutting-off the PCV - but to be honest, that's a pure guess.

How much oil does it appear to be using - and have you done the smell test with the oil?

Edited 21 January, 2023 by Warrior193
Typo

[Scvrs2]

I haven't been out to do a smell test yet but I'll let you know. From what I read somewhere the PD engines don't have a PCV as such but a CCV, is that right? Appears to be using about a litre of oil every 150/250 miles. 

Smoke appears to come from the back of the engine too, maybe a rocket clover gasket...? 

[SuperbTWM]

48 minutes ago, Scvrs2 said:

I haven't been out to do a smell test yet but I'll let you know. From what I read somewhere the PD engines don't have a PCV as such but a CCV, is that right? Appears to be using about a litre of oil every 150/250 miles. 

Smoke appears to come from the back of the engine too, maybe a rocket clover gasket...? 

 

Yea there is no PCV valve to speak of on the PD engines, not that I can remember anyway, the top end is usually at pressure anyway due to the tandem pump exhausting into the rocker cover

 

Do you get this smoke while driving or idling? Is it visible in the warmer weather?

Edited 21 January, 2023 by SuperbTWM

[Scvrs2]

Both driving and idling but on a long run it seems to go away! It's been slowly getting worse over the last few months so I'd say it is there on Warner weather too, although it's now so bad I can't see behind me! Unless I unplug the maf then it's fine! 

[Warrior193]

1 hour ago, Scvrs2 said:

I haven't been out to do a smell test yet but I'll let you know. From what I read somewhere the PD engines don't have a PCV as such but a CCV, is that right? Appears to be using about a litre of oil every 150/250 miles. 

Smoke appears to come from the back of the engine too, maybe a rocket clover gasket...? 

I assume that it's not also dumping sump oil on the ground?  A litre, even at 250 miles, sounds pretty bad. 

[SuperbTWM]

The most likely culprit to me is the turbo if it’s burning that much oil. You wouldn’t push that much through the CCV and the engines are usually strong. 
 

 

[Scvrs2]

Turns out I had 3 bad glow plugs and that was stopping the dpf getting to temperature and blocking it up. Back pressure was causing the smoke! Glow plugs changed and now to regen the dpf and hopefully that'll solve the issue! Thanks for everyone's help and opinions! You may still be right but for now I'm hoping that the dpf will Regen and all the smoke will go! 

[Warrior193]

I'm hoping that I'm wrong - but I suspect your problem is not just the glow plugs. AFAIK, they only activate at start to assist initial combustion.

[Scvrs2]

47 minutes ago, Warrior193 said:

I'm hoping that I'm wrong - but I suspect your problem is not just the glow plugs. AFAIK, they only activate at start to assist initial combustion.

I had a look online and apparently glow plugs are used to help the dpf get up to temperature and burn off the soot. If the glow plugs fail then the dpf starts to block, dpf was/is definitely starting to fill up, this seems have caused back pressure and therefore oil blowing up through the crankcase. When Maf was unplugged it shut down the egr and stopped the pressure blowing through the case so much. All this is just what I was told based on some diagnostic readings and educated guesses! The smoke is definitely improving after new plugs so fingers crossed! But you could still be right, I just hope you're not! 🤣 Thanks again for all the help everyone, once again this forum proved a lot more helpful then all the others! 

[SuperbTWM]

Never heard of glow plugs helping a DPF regen, if anything they could result in pre ignition of the unburnt fuel that is destined to burn in the DPF which seems counter productive but happy to be proven wrong as always.

 

It is always better to have them operational though as it will sure help the engine's combustion after initial starting in cold weather.

 

Did you have the DPF lights on? if it was that blocked you should of had multiple warning lights