CCV pressure, possibly gone turbo?

[vpavlov]

Hello again.
I've recently made a post about blown turbo with my 2005 Seat Alhambra.
Well, I replaced the broken turbo with a reconditioned unit about 2 weeks ago.
Up to now the car had been driven for about 1000 miles with the new turbo.
Today I decided to check on the state of the turbo - the compressor wheel particularly.
Externally the unit was in good condition with no visible leaks or anything.
But... When I opened the hose from the air filter to the inlet of the compressor housing there was a thin layer of oil on the inside of the aluminium housing - on the bottom. This immediately ringed an alarm in my head...
I came to the conclusion that there were maybe two possibilities:
- excessive crankcase pressure not allowing the oil to flow through the oil return line in to the sump.
OR on second thought
- oil fumes from the camshaft cover/CCV entering the inlet pipe directly after the air filter and seeping into the turbo inlet

When I installed the turbo there were not any unusual sounds from it for around 5 minutes at idle, but after that the sound changed as if the VTG was engaging. The car (the turbo is a little bit noisier when started in the morning but in ar. 5 minutes it settles. The sound from the turbo is heard distinctly with open windows - especially when the VTG opens or closes the fins. With closed windows the turbo is heard very faintly - in frist or second gear, after that the road noise overcomes the others.
The turbo was installed properly:
oil in the oil inlet
new gaskets
all the pipes cleaned
intercooler cleaned
oil and oil filter change
starting the car for 10 minutes idling

My questions are:
Is there a way to check on the CCV ventilation? I've opened the oil filler cap and it "danced" around but it is normal I presume.
Is there a way to ascertain whether the oil comes form the CCV or the turbo itself?
Should I try to clean the CCV ventilation on the camshaft cover?

[vpavlov]

Forgot to mention - the shaft of the new turbo hasn't got any noticeable play (radial or axial) at the moment (after 1000 miles) - I inspected it today.
Thanks.

[johnnyroper]

It's normal to have some oil most forming in the turbo due to the design however when on boost the sucking created by the turbo drawing air in should close the crank case vent in rocker cover. If it isn't then I would expect oil blow by to be quite severe.
I have used a manometer in the past to check breather pressure but I would have no idea what is acceptable on these engines,as far as checking vent closes when on boost apart from changing rocker cover then only way I can see to check is by routing breather through a catch can and seeing how much oil is carried over?

[vpavlov]

Thanks for the answer.
As I understand the function of the valve in the rocker cover:
- it is a spring valve that is used to vent (mainly) the air/oil mix form the rocker cover/crankcase to the inlet pipe to the turbo
- the main function is to release the pressure form the rocker cover/crankcase
- when there is enough pressure in the rocker cover (maybe all the time for a TDI) the valve is opened to release that pressure to the turbo pipe
- the suction on the side of the turbo pipe works against the opening of the valve - i.e. when there isn't enough pressure in the rocker cover the suction closes the valve
- there isn't any type of mesh in the valve to catch the oil mist from the rocker cover from entering the inlet pipe to the turbo so oil enters freely the turbo pipe
- standard check for blowby/valve is to open the oil fill cap... The cap starts to hop/dance on the opening fo oil filling... Pinching the rubber pipe from the rocker cover to the turbo pipe makes the cap more "jumpy" - i.e. the gases from the rocker cover are not entering the turbo pipe and find their way through the oil fill opening.


I don't know about the trueness of the above statements but this is my understanding of it.

[johnnyroper]

I am under the impression the valve is permanently open and then when on boost the suction overcomes the spring to close the valve to prevent the turbo consuming the engine oil.


If it worked like you think it does the 'standard check' would not work as taking oil cap off would release pressure so the spring would not be overcome and pinching pipe would have no effect.

[vpavlov]

Hello.
I got the information about the valve from here:
http://www.t4-wiki.de/wiki/Kurbelgeh%C3%A4useentl%C3%BCftung
And the trick with the pinching from here:
https://www.youtube.com/watch?v=4GddZqt46gg

[johnnyroper]

That goes with what I said that valve is open all the time as the gasses exited when pipe pinched from filler cap,therefore it cannot be closed all the time until pressure has increased enough to overcome the spring and open the flow to turbo.

[mike wilson]

I don't think the guy who uploaded that video understands how crankcase ventilation works.

Yes, if it blows the top off or there are excessive fumes there is serious blowby.  But that video looks perfectly normal to me.