A6 3.0 TDI - sudden smoke & oil loss

[Crasher]

Was the front pipe disconnected from the turbine housing to check for oil in that side?

['WG']

Yes, all pipes disconnected. Only sign of oil was in charge air pipe to towards the intercooler. No oil in exhaust. Turbine dry.
I can’t think why the CCV & pipe would be apparently blocked solid on the car, but now miraculously allows full unrestricted flow now it’s off in pieces.
I’m sourcing a pipe to suck/blow test the CCV aperture, but would have thought its just a hole in the crankcase...
All this work and still absolutely no clue what could be wrong. Now I understand why warranties are so expensive!

[Crasher]

I was hoping to not have to suggest this but the way the flow cleared suggests you need to change the pressure control valve for the crankcase breather system 057 103 495 N £172.87, a bit of a pig of a job as you have to remove all three inlet manifold sections and the EGR cooler.. The Audi book time is a shade under three hours which is hysterical, it's more like double that if you know the job and everything goes well.

['WG']

That’s exactly the same reasoning I had, so went ahead and did just that expecting crud in pipe and/or CCV(/pressure control valve). When I eventually got there(my god what a mare of a job, you’re right), the valve looks like new. No crud. Not blocked. Fresh air easily blown both ways. Pipe clear too.

Actually, I think I may have boobed, as I forgot to blow/suck with the oil filler cap off (duh), which probably explains why it felt blocked. I’m going to recheck that theory soon. It still seems odd that the ‘valve’ blows both ways though. I can’t even see the membrane in there to make it a ‘valve’ of sorts I suppose, but so long as it’s not actually blocked I don’t see how it can be causing my issue. If there’s no working membrane, that’ll just mean less oil separation, and more in the charge air than normal, but surely it wouldn’t suddenly pull all my engine oil out in 30 mins of driving. Some people remove the membrane deliberately for peace of mind (so it can’t block or cause problems) and then fit a catch can at the intake end. When mine suddenly ‘blew’ the breather wasn’t even connected to the intake (had been venting to atmosphere with a filter for months).

I’m beginning to suspect a head gasket (by deduction), but there’s no oil in the water, no rough running. I just can’t think what else this could be.

However, all my best guesses so far have been wrong. I’m fast approaching the point where I‘ll have to call it a day, draw a line and sell it for spares or repair. The next owner might get lucky and work it out first go. Gutting.

If anybody fancies their chances, let me know.

[Crasher]

Never ever give up, fight it to the death... It is what I have always done and I am still here.....just.

['WG']

Thank you for your help and support, but this is the tail end of two years of endless problem solving with it. My ‘never give in’ style has already cost others too much and is ultimately a selfish indulgence. Endless diagnosis is futile without a realistic prospect of success. Eventually, one has to cut the losses and move on.

[Crasher]

I never give in, it is only a machine designed by a person and whatever is wrong I can beat it until I die doing so, technology will outlive me but I will go down diagnosing...

['WG']

It’s fixed. I couldn’t face letting it go and I didn’t like 'losing'. I just kept driving it despite the oil loss and smoke and after 50 miles or so it suddenly righted itself. So, either it was self-inflicted by removing the ccv and venting (filtered) to atmosphere, or something inadvertently got corrected during the work. No idea how it led to such catastrophic oil loss and smoke, but it’s ok now.

[Sloppy]

did this ever return,

ive got a a4 3.0 tdi which smoke on idle after a while, blue smoke,

its had injectors tested and i fit a new turbo still the same, goes much faster now but still smokes on idle?

checked pcv for pressure none obvious?

[Crasher]

Is it using oil or water and any signs of this?