Diesel in Oil

Hi to all, I’m Paul and I have a 2001 D2 TD5 which I’ve owned for eleven and a half years.

I’m getting a diesel leak into the oil which I’d consider to be a slow leak...
I know diesel/oil mixing is well documented to be an issue with the head but after adding UV dye to the fuel filter I expected to see the dye leak from the fuel rail area or injector pockets or injector rubber seals but all five injectors were leaking from the around the plunger.
I replaced all five with recon Delphi injectors from Land Rover and found exactly the same result. While the injectors were out I also dye checked the injector pockets and all were fine and changed the diaphragm in the fuel regulator to eliminate any issues there but still getting a slow mix of diesel/oil.
Have leaking plungers been seen before?
I will be checking fuel pressure at the weekend as I’ve bought a pressure test kit and wondered if an over pressurising fuel pump could force fuel past the top of the injector, a new pump bought from Land Rover was fitted December 2018 so should be under warranty if the pump is to blame.

So has this issue been seen before? Over active pump or two lots of bad injectors? (unlikely)

Diesel in the oil is either injector O rings or a cracked injector port. Either way, with the rocker cover off and the system on fuel purge you should see it bubbling up from around one of the injectors. The injectors won't be the problem

Hi Tom, thanks for the reply.
New rubbers and washers were first fitted on original injectors, dye test found diesel at the plunger so changed injectors which came with their own washers and rubbers, pockets were tested while injectors were out and found to be good. The dye is coming form where the plunger goes into the body of the injector and that’s on two sets of injectors. I’m trying to eliminate that trace of fuel so if the leak persists then will then know it’s time to get the head checked.
With no trace of dye on the visible part of the fuel rail is it possible for a crack to appear on the return channel or is it usually the pockets or feed side of the fuel channel?

With the rocker cover off and the system on a fuel purge cycle can you see any bubbling?

No bubbling, plus bubbling fuel would be also traceable with the UV dye I’m using too. The only place I’m seeing dye is to plunger of the injector. The cylinder head had been cleaned thoroughly on the fueling side when looking for traces of dye and the only traced were at the plunger, so is there a possibility the leak is on the fuel return channel and not on the visible feed and port/pocket side. I have pictures of the dye leaking from the plunger and will post once I’ve figured out how... photo bucket I assume

Paul18k said:

No bubbling, plus bubbling fuel would be also traceable with the UV dye I’m using too. The only place I’m seeing dye is to plunger of the injector. The cylinder head had been cleaned thoroughly on the fueling side when looking for traces of dye and the only traced were at the plunger, so is there a possibility the leak is on the fuel return channel and not on the visible feed and port/pocket side. I have pictures of the dye leaking from the plunger and will post once I’ve figured out how... photo bucket I assume

Click to expand...

This is a strange one, not heard it before.
Try upload direct, click upload a file click the little green box when you type the post, then browse your computer until you find the picture then select it and upload, the you will see a small picture with two options thumbnail or full size pick full size.
Good luck

Thanks raywin
Yellow dye from plunger pic

this is just one of the injectors but the same trace was found on all five and two different set of injectors, if I can eliminate this leak and the problem persists then its got to be the head but can’t move on till I eliminate this trace