The problem started this summer. Had o-rings replaced, tandem pump re-sealed. Fuel is still leaking into the sump and every mechanic I went to is stumped.

Just because you have replaced the seals on the tandem pump does not mean it has not failed internally and is leaking fuel into the engine.

 

You could also have a bad injector seal.

 

You need to find somebody who knows PD engines a VAG specialist maybe, its not rocket science.

 

First thing I would do is replace the tandem pump completely as this is the easiest part to replace

 

 

Edited 5 November, 20187 yr by SuperbTWM

DPF cars can dump fuel into the sump during regeneration I believe as the injection is modified.   Or so I read somewhere.  Don't know if it applies to the 2.0PD.

1 hour ago, jimbof said:

DPF cars can dump fuel into the sump during regeneration I believe as the injection is modified.   Or so I read somewhere.  Don't know if it applies to the 2.0PD.

 

Any car with a particulate filter can do this although with a PD engine its actually less likely as the injector timing is fixed, this is why DPFs don't work very well on PD engines but its usually the result of a DPF issue or doing short runs that causes the car to actively regenerate over and over again. The extra diesel in the combustion chamber contaminates the oil and can cause the level to rise over a period of time.

 

As it is fairly obvious when a car is trying to regen (fans running, burning smell, high idle) I would hope the OP would have spotted this and mentioned it.

Edited 7 November, 20187 yr by SuperbTWM