BLS Oil Leak: Tandem Pump Area

Good day!

I'm reaching out because I'm currently at a loss and hoping for/asking for help!

"Vehicle: Caddy2KA, manufactured in 2006 (105 horsepower), with 300,000 km mileage. The turbocharger has 130,000 km, the tandem pump has 5,000 km, the valve cover has 1,000 km, and the DPF (Diesel Particulate Filter) has approximately 10,000 km."
The boost pressure, EGR values, and coolant temperature are all within the normal range.
The oily issue is estimated to have been present for about 30,000-50,000 km, but it's now getting worse and I really need to address it.
"In reality," there is no oil consumption. The liter that I have to top up every 15,000 km, I attribute to a leak.

The turbocharger hoses have been visually inspected and manually checked for leaks, and they appear to be tight with no signs of oil leakage. The tandem pump is also sealed all around; it has been examined both physically and with a camera. When the valve cover was removed yesterday, it appeared to be sealing properly. There's no oil leaking downwards. However, starting from the intake manifold on the outer side, near the gearbox, there was oil present around the seal.
The turbocharger itself and all of its oil lines are also dry.
The crankcase ventilation seems to be sealed properly. At least, there's no oil leakage in that area.

Error description:

After a cleaning and a highway drive at a constant engine speed of 2500 RPM over a distance of approximately 500-1000 km, a small oil streak initially forms, about 4 cm wide, in the location shown (see picture). When driving the same distance under full load, which results in an engine speed of 3200 to 4000 RPM, the engine looks like it does in the picture. After several thousand kilometers, a drop of oil occasionally hangs from the EGR cooler.

Could it be the head gasket? But why does it seem to depend on the load?
Surely no oil can leak out of the intake manifold, right?

I hope I haven't written too much nonsense here, but I would be very grateful for any positive feedback you might have.

"Where exactly does it come out? That's important!"

Under load, the oil becomes hotter and consequently thinner.

Rüdi wrote:

Exactly where is it coming from; that's important!

Located near the turbocharger or intake manifold. It's not easy to pinpoint exactly where it is, as both parts are mounted closely together. But could it really be there?

The boost pressure is higher with more load, so I imagine that a bit more oil mist might be pushed out compared to when the boost pressure is lower.

You were right. The left channel (on the transmission side) was leaking. One steel nut wasn't as tight as the others, even though everything was assembled uniformly according to specifications at the time...

Thank you for the feedback!

What's worrying me now is this picture, see the attachment! It shows an oil film in the leaky pipe. Or should I be less concerned about that...?


-The engine starts immediately without any hesitation, even in cold temperatures.

- I haven't observed any smoke while driving, except: With the old DPF (original, only rinsed with water at the time, year 2012), the engine would occasionally produce a brief puff of smoke during cold starts. Since a new (non-VW original) DPF was installed in 2019, the engine no longer smokes during cold starts. However, I've noticed that with the new DPF, it produces a larger cloud of smoke from the rear when the regeneration process begins, but only when accelerating.

Hello,

If the oil in the image from the combustion chamber were coming from there, the engine would definitely be producing white smoke while driving.

If he doesn't do that, hopefully it leaked in during the expansion process. It's practically impossible to have liquid oil in the exhaust manifold due to the high exhaust temperatures. However, if it does happen, you'll notice something is wrong without needing to be an expert.
Then, looking in your rearview mirror, you'll only see a white-gray wall behind you.

During the regeneration process, no smoke should come out of the DPF; none of my vehicles have ever produced any smoke during this process, and I haven't observed any smoke while driving on the road either.

Best regards, Rainer.