Well I pulled my sending unit in hopes to get the gauge to stop bouncing around...well couldn't fix that, just screwed up my thumb and broke the low tank wire Well anyways, I noticed oil on the sender unit....took a peak in and the fuel smells horrible like gas...thought its not and its milky white/grey color. I have heard that a bad lift pump can introduce oil into the fuel system....I had a newer style primer pump, that I pulled from PNP...stuck that on and I did get a little power increase....but I won't know if that was the issue, till I burn out what's in the tank and refill a few times....curious if the lift pump is the only thing that can introduce oil into the fuel system?

__________________

Unless youre secretly doing a WMO experiment...

__________________
Current fleet
2006 E320 CDI
1992 300D - 5speed manual swapped

former members
1984 300D "Blues Mobile"

1978 300CD "El Toro"

Wait, aren't there some on this board that think this is a good thing???

Seriously, maybe something leaking inside the IP that is passing oil into the return line.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Can't be oil if it's a diesel, which should be black.

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

I think you may have found him out...

__________________
"Senior Luna, your sense of humor is still loco... but we love it, anyway." -rickymay ____ "Your sense of humor is still loco... " -MBeige ____ "Señor Luna, your sense of humor is quite järjetön" -Delibes

1982 300SD -- 211k, Texas car, tranny issues ____ 1979 240D 4-speed 234k -- turbo and tuned IP, third world taxi hot rod

2 Samuel 12:13: "David said to Nathan, “I have sinned against the Lord.” And Nathan said to David, “The Lord also has put away your sin; you shall not die."

Milky white almost sounds like some water may be getting into the tank....how is the seal on the fuel tank filler cap look?

__________________
2012 Mercedes ML350 Bluetec 91K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 231K (mine)
1998 Volvo S70 T5 Turbo 196K (kids)
1994 Ford F150 4WD 249K (firewood hauler)
1983 Mercedes 300D 376K (diesel commuter)

Sounds like a fair amount of water mixed in. I would remove the fuel and settle out the water then return the fuel portion to the tank if wanted.

Water through injection pumps being like sandpaper . The separated fuel should be reusable. Or install a water trap in the system. Also you might consider finding another place to fuel if currently you are only using one vendor.

You might do a separation test for water in your fuel. Drain about a quart into a glass Mason jar and let it settle for a few hours, looking for a fuel/water separation. We did this easy test on aircraft in the military.

However, you may not have fuel "problems" at all. Diesel fuel is naturally a little "dirty", due to the way it is refined at low distillation temps. Here is an article that describes some of this: Source Of Diesel Fuel Problems

__________________
Sam

84 300SD 350K+ miles ( Blue Belle )

For sure not attempting a wmo experiment, though I thought about it....after an oil change, then I read the commits on wmo and I seen its not a good idea.....

The gasket on the fuel tank cap is new...

Didn't think about water in the tank....

The last places i got diesel was at Chevron.... And before that the same, haven't thought about bad fuel...

How do I explain the oil on the sender?

Also I was or should I say thought I was burning a lot of oil, I assumed the worn engine was accounting for the oil consumption, now I am wondering if it was being sucked into the injection pump....

I don't personally think my fuel would be black, unless I was burning wmo....and that I am not.....

__________________

Do not worry about it.

1) Any engine oil return from the IP ( if there is a problem at all ) will be so minute that it would be diluted by the diesel. Oil and diesel mixes well.
2) The fuel gets into the sender thru a small hole. So the chance of any oil ( not mixing with diesel ) and got into the sender is next to nil.

The oil or oil liked substance you see probably are crud deposited/accumulated inside the sender for the last 30+ years.

__________________
Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.

Oh I am not, you know the saying "curiosity killed the cat". Well I am the cat

I had the tank out and got a used sender about a year ago, I took it apart and cleaned it then too.....so that's what got me curious...

I think chances are I just got bad diesel or really old diesel from the last station I went to...

__________________

Pull a sample and see if water settles out as someone suggested. It still sounds like you have a lot of water.