617 Fuel pump.. leak fuel into block/sump??
 

seem to recall long ago a few suggesting it possible that OEM mechanical fuel pump on 617 can leak fuel into sump; as it gets very worn.. rare-ish but can, any info on that out there in the Netispher?

I am one of them but not the only one.

In post #2 of the below thread see the pic and the green arrow points at the O-ring in the fuel supply/lift pump that separates the fuel from the pump oil sump that intern drains down into the engine sump.

No one has said it has happened so far, but the barrels/elements of MW Fuel Injection pumps are sealed on the bottom with O-rings. However, removing the elements ruins the fuel adjustment that is done for each element. And after those O-rings are replaced, you need to have the pump re-calibrated.

You also need to get the elements back into the hole they came out of and you cannot mix any of the element parts with other elements.

I have not looked for a long time but there is real Bosch and generic made rebuild kits for the fuel supply lift pumps. You need to be sure the kit has the 5mm O-ring because there is a valve replacement kit with zero O-ring in it.

http://www.peachparts.com/shopforum/diesel-discussion/389939-om617-n-lift-pump-rebuild.html

There is old threads on the lift pump rebuild with part numbers for the kits.

Thanks; so not to fawk around with another variable of something else I maybe screwed up ... I've ordered a rebuilt lift pump from a fellow in Greece. He has been very helpful. Wont be here till mid Aug. Will swap it on when arrives. Eliminate another potential issue before it is an issue. .

with more thought . do think mechanical lift pump is leaking. Explains too much... llike seemingly not holding a prime (or Im miss diagnosing that and this is not actually happening. and its bad IP instead?? or jumped a tooth.. or?

Also when removed RIV port cover the oil that came out felt to low in lubricity. like it had diesel in it. Thinned out lube might also explain all my oil leaks. My all brand new Oil lines using AN fittings (new line to turbo, new line to external oil filter head, new to oil temp thermostat. new to oil cooler.. and new line back to engine...and the few times engine has run in testing they all FIGHT me and seem to leak everywhere. Now its just the oil filter itself seems to leak out somewhere in that area and one line on the cooler. Or (and mostly this) I fawking suck and making AN lines (but I'll pretend it is the diesel in the oil and cheap chinese shiat AN fittings)

Annnnyway just to remove a variable . made up a line today to bypass the mechanical lift pump all together. For now will run the elec. pump only. Put that Elec. on a switch, into the new fuel system just in case of issues and I need to keep going with an air leak somewhere or or or?? New system is all AN lines I made up from Engine all the way to bottom of fuel pick up in tank. Its all new Fabri-hacked system. Though not hooked up yet. even have an aux. fuel polisher that will kick once a day (separate small solar charged battery runs it)

Well, I used to work in a fuel injection show for 5 years where I rebuilt fuel injection pumps and on non-Mercedes inline fuel injection pumps, I have seen that 5mm O-ring cause the fuel in the oil issue.

Some have said it can also go the other way around where the oil is sucked out of the fuel injection pump and mixed with the diesel fuel and burns. Over time causing unexplained low engine oil levels.

Any way it is a cheap fix. If you remove the fuel supply lift pump, be careful as the cast flange is a brittle casting. Don't grip the flange in a vice.

interesting stuff. Appreciate muchly.