Viano grey smoke saga

[Steeelyglint]

Hi some advice please. Viano with 98K on clock. No engine warning light on.

Apologies for long post - need help already feeling a bit sick with worry on this one.

Had grey smoke issue with car for a while ( couple of posts already) which became quite dramatic recently on way to work and I drove straight to my Mot garage for a diagnosis.( not MB specialist)

They rang me later to say it was a turbo issue. I've paid ( A lot) for a replacement and picked Viano up on Monday. The car is still smoking which the garage says is just burn off from the exhaust but which I think is more.

If I start car no smoke for first mile or so until engine is warm and has been driven, Smoke not always there, mainly grey and is most dramatic as I pull away and is worse in crawling stop start traffic I.e.my journey to work

Bur when sat stationary with car ticking over for 10 mins ( whilst I looked for OBD port) no smoke at all.

Drive car 10 mins and stop at lights and there can be an embarrassing amount of grey smoke smelling of oil. Seems to be getting worse and worried I am going to goose a brand new turbo. Car seems to be using oil too but hadn't until this issue started.

I suspect it's a PCV check valve issue.

I now have access to code reader but have insufficient skill to know what to look for ( but know how to use)

No error codes other than intermittent fault on glow plugs 3 &4 according to garage.

Searched forums but any related threads but they never seem to conclude.

Other info. A few years ago oil leak under bonnet was traced to dip stick coming free. It was fixed with a tighter o ring. I now think that might have been check valve failing and dip stick being forced out by crank case pressure.

Questions

Could it be PCV check valve? Alone or in combination with new issue?
is there a definitive way to check the crankcase vent system?
How can a check valve fail in a way that blows a turbo?
Should I take cam cover off to have a look for sludge. etc. & if so will I need new gasket?
Are there simple checks I can do with turbo hoses?
Should I ( get garage to) do a compression test?
On my engine is my check valve maintainable or is it part of engine cover?

Any other theories?

Want to avoid spending money on something that may ultimately be uneconomic to repair. As always any help really appreciated.

 

[Steeelyglint]

VIN. WDF639815********
Model CDI22TRE/E4X2 3430
Production Date2008-02-11
MP3Engine OM 646 DE 22 LA 110 KW (150 Hp) 3800 Rpm

 

[Petrol Pete]

If its grey smoke coming out of a diesel vehicle and it smells like burning oil ...it probably is. You don't say if its coming from under the van or out of the exhaust pipe.

No smoke when stood idling for a while but smoke when driving away could indicate an oil leak onto hot surface when the engine is under load.

I had a strange 'oil' experience years ago with a Toyota Carina that was using oil, I couldn't for the life of me find where it was going until one day in anger/desperation while under the bonnet I wrenched on the accelerator cable and revved the nuts off the thing only to see a thin jet of engine oil escaping in a perfect arc onto the tarmac below , not touching a single other part of the car. These were the days before under trays and countless pipes and gizmos to get in the way.

The pressure sensor switch on the side of the engine block had some kind of fault/pin hole in it !! . not much help to you I know, but it could be something as simple. Good luck

 

[Steeelyglint]

Hi thanks for reading my essay! no oil leak under car, 95 % certain oil is from exhaust tail pipe.

 

[Steeelyglint]

I took off the air box to look for the PCV check valve or equivalent. The black rubber pipe to left of Allen key joins black rigid air inlet to turbo and comes from under this black cover - no sign of check valve. I thought I'd take the black cover off but as soon as I cracked (15 degrees) this cap head, fluid came weeping up around it. I retightened sharpish As I don't have any gaskets etc I stopped. Am I safe to proceed and is this typical phenomenon?

 

[Steeelyglint]

 

[Steeelyglint]

View attachment 90026

 

[Steeelyglint]

minor update.
good news : have researched and for my engine (646.980) there is a separate oil separator under the black cover. when you google it as a part (£30 ish) it is described as having a diaphragm as well so I think it doubles as a PCV check valve

bad news: if you take the dipstick out with the engine running, engine oil spews out of the dipstick "pipe". If you remove the oil cap it doesn happen. Clearly the dipstick pipe is dipped in oil and crank case pressure is forcing oil out of the dipstick pipe.

so I either have a breathing problem (heres hoping) or its mechanical i.e. so much blow by the pistons that the breather cant cope...

If anyone knows how a 646 engine "breather" system works please let me know...

 

[Steeelyglint]

One more post into the void....
Have replaced oil separator (£90 part from Mb) and grey smoke has gone completely . Will have to drive a while to see if the car is now consuming excessive oil but I think it is sorted. Wonder if this is what killed the turbo or if the turbo was just oily because oil was passing through into exhaust and the garage misdiagnosed.? . Glow plug intermittent fault also seems to have gone., could that also be caused by too much oil in cylinder??

 

[GaugeBoson]

Excellent that it is sorted, but a shame that it cost you a new turbo which would appear to have been a 'guess' diagnosis by your MoT garage. I would imagine that the intermittent fault on the glow plugs was based on the engine management system detecting an abnormal electrical resistance; it could just be that where wiring has been disturbed during the turbo fitting that the connectors to the two errant glow plugs were moved are now making better connection.

 

[Steeelyglint]

There was a lot of oil in the exhaust so I am telling myself that the blocked engine breather somehow led to blown turbo oil seal and a £900 bill. It's a bit annoying that such an expensive fault goes "unnoticed" by the engine management system and therefore invisible to digonosticians.