Schwarzer Diesel! | Posts 16+

Hello Rainer,

In the illustrated link I attached, "TraZvis" (the mechanic who disassembled the tandem pump) mentions that it took him approximately 5,000 km for the filter to become completely sealed again.
Alex replaced the filter for the second time after just two days. At that point, there wouldn't be much visible debris in the filter yet. Furthermore, the oil is not being sucked in in large quantities, because those affected do not notice the defect through a decreasing oil level, but rather through the other symptoms described.

/Jan

User Malzhirn will surely get back to us and report on things...

@Jan03: Your suggestion is good and makes sense, but I don't see insisting that it *must* be exactly this as helpful.
I myself have already filled up with diesel that turned everything black afterward. And that's in a vehicle that doesn't even have a tandem pump, let alone any connection between the fuel system and the oil circuit.
Perhaps you own a gas station, which is why you are so categorically excluding this possibility?

Best regards, Rainer.

I've already replaced many diesel filters, and they were all black.
It could be due to adulterated diesel, but if that's the case, it would have to be happening at all gas stations. I also suspect that this contamination is coming from the tandem pump.

The declining quality of diesel fuel is also evident in the increasing number of high-pressure pump failures in common rail (CR) systems.

Hello everyone,
Startled by the new readings, I immediately checked the oil filter. Again, it was black. Not as extreme as the first time, but still black. Then I checked the oil level and was shocked - it was overfilled! I hadn't added any oil since the last oil change. I had to pump out about 1 liter to get it back into the "normal" range. Oil dipstick is coming. I think that is quite .

The original pump costs approximately €360. A Pierburg pump costs €225. Does she do it or not?

By the way, I read that you can check the fuel pump for internal leaks. This involves disconnecting the supply and return lines at the pump. One of them is closed off and a pressure gauge is connected to it. The other line is pressurized to a maximum of 1 bar, and the air supply is then shut off. If the pressure cannot be maintained, the tandem pump is leaking.

I think I can skip this exam .

Well, in that case, I would also consider replacing the tandem pump.
However, the BMM system, along with its software related to the DPF, can also allow some diesel fuel to bypass the cylinders and enter the engine oil, especially during the active regeneration phase. But 1 liter per kilometer is quite a lot.

Quote:

A pump from Pierburg costs 225€. Does she do it or not?

Pierburg always delivers. Exception --> LMM.

How many miles have been driven since the last oil change?

I have a similar case here with a Passat 3B6 equipped with a DPF.

He needs approximately 2000 km for each liter of oil increase. The tandem pump would then be a likely culprit.
Let's see if he can get it repaired or if he's going to sell it.

The last oil change was about 6000 km ago!

You can purchase Pierburg products without hesitation, especially when it comes to tandem pumps, EGR valves, or similar components.

Many Pierburg parts even have the original VW part number stamped on them and then milled out, which suggests the same manufacturing process.