Oil filler neck leaks 35d 2011

[serge1]

How does oil get into intercooler?

Mostly, due to poorly designed crank case ventilation, specifically filtering of liquids and gasses.

I bet if you take off hose #5 in diagram below, you'd find it fully soaked with oil. In fact, so soaked, it will likely rupture(.

[AnShk]

Originally Posted by serge1

That has to be oil leaking out of intercooler. May have been quietly sloshing in there during previous owner's time, then you driving it hard introduced more boost than normal into intercooler. The seals (designed to hold pressurized air, NOT oil), must have finally gotten deteriorated by the oil and allow it past.

The seals are #2, #3, #13, #14 here:



I had a similar issue around 40K miles.

wow, do you remember the error codes?

Are these seals easily accessible or not?

[serge1]

No error codes. Just had oil drip on ground like in your case.

The seals failing only unmasked the real problem, problem of oil present there in first place.

If not taken care of, anti-shudder valve (#4 below, a $220 part) will eventually get its electronics soaked in all that oil and fail. Failed for me. That one will have a code and rough engine stops (engine will shudder when stopped). Another, perhaps more important, function of that component is to prevent diesel runaway. With so much oil present in the incoming air, the diesel may just run away. The function of the anti-shudder valve is to close off air supply and stop the engine.

Next, the oil in the incoming air is getting baked by hot and sooty EGR gasses entering through EGR valve (#1 on the diagram). As result, intake manifold gets layers and layers of carbon buildup.

If you won't be taking care of crankcase oil/gas separation to remove presence of oil in the air stream, I'd at least take off the intercooler and wash it at the same time when replacing the seals. I would also take off the anti-shudder valve, egr cooler, and exhaust manifold and have them cleaned, too. All that would take a couple evenings, but will buy you 10K miles.

[AnShk]

Oil leak was at turbo boost hose. Hose not clipped properly causing oil blow by. Hose is not damaged.

[AnShk]

Opened belly pan and found oil leak from the same hose.