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gomi_otaku, Technician
Category: UK Car
Satisfied Customers: 3462
Experience:  VW Technician, VW FastTrack, VW Academy, VW Certified
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09 VW golf tdi (cbab engine) - Problem with oil leak inside

Customer Question

09 VW golf tdi (cbab engine) - Problem with oil leak inside the ASV's black housing (where gears and DC motor is located). Very much oil here..
The EGR and ASV has been cleaned after MIL came up last year. Fault: Stuck open/closed.
Mechanic wanted to change the ASV because of the fault and also said I needed to change the EGR because it was leaking (oil on the underside of EGR).
After cleaning no MIL has come up for a year before the other day. Though I have had engine shakes when turning off the engine the whole time.
Disassembled the ASV and EGR and as said, the ASV was full of oil inside the black housing. Egr was clean here..
I suspected that the wheels were worn and that was the problem with the opening and closing fault. Both the EGR and ASV's gears are completely in good order, no sign of any wear.
The question is why would there be leakage inside the ASV - where does it come from? The gaskets-rings between the black housing cover and the valve were like new.
I'm wondering if there is to much oil coming in through the valve's from somewhere, where someone mentioned turbo and possible runaway candidate..
I have checked both side's of the IC hose' for any fluid and they are both clean with just a few drops of black oil coming out (which I've been told is completely normal for diesel's).
I understand that the ASV is probably faulty, since it's not closing when turning off the engine. But could that have anything to do with the amount of oil inside the black housing cover?
The air (with moist oil) just flows right through the valve and further in through manifold anyway, so why would it suddenly leak oil into the ASV's cover?
Is it because the EGR was leaking and the leaking went further to the ASV where it leaks into the cover?
When I disassembled the ASV and EGR the other day, there wasn't any signs of leakage underneath the EGR like last time.. So I'm thinking, a new situation? Seems that in this case I've tightened the EGR so it stopped leaking? But then where would the leak inside the ASV cover come from?
It could also be that the ASV has been full of oil since last year, because I didn't open the black housing to check inside. Since the engine shakes are still here it could be it hasn't been working all this time. But why not an MIL?
Right before I got the MIL this time, the car was juddering and I felt like I heard the gears trying to open and close on of the valve's.. That is why I thought it would be worn gears..
I'm thinking of buying a new 12V dc motor for the ASV. But I don't know if this will solve the leak into the cover..
Submitted: 1 year ago.
Category: UK Car
Expert:  gomi_otaku replied 1 year ago.

There is always oil coming through the intake- due to the small amount of seepage at the turbo seals, which is normal. If you take off your lower hoses you will dump out a half cup or more.

This oil gets flung around in the air, and will stick to any surface it contacts, and will run down. There are just certain areas it tends to collect, as there are obstructions in the airflow. It's been like this on every generation of the diesels.

The EGR tends to get more sooty and dry deposits over time, not wet and runny.