I checked this out last summer when I was trying to pinpoint my wonky fuel gauge. I pulled the unit and was to my surprise relatively clean. The outer coat was black but there wasn't any sludge on the inside of the unit either.

My issue was ultimately a bad ground in the cluster itself. Either way it's a good idea to clean it.

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-Typos courtesy of my mobile phone.

About three days ago my fuel gauge started bouncing badly and the reserve light flashed like a blinker light!

I pulled the sender and found that the bottom nut and plate were gone. I nearly lost the metal tube while pulling the thing out!

Question is: I have made a bottom piece out of an old ACC vacuum pod, but I need to find a tiny nut to go back on there....anyone know the correct size for the nut?

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----Adam

1985 300SD 322,000

Grab another sender from the salvage yard.
Gasoline or diesel will have the same plate and nut.

JimmyL may have a spare.

With reference to the photo in post #14, is the thin wire one whole wire looping at the botttom or are they two separate wires?

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'85 300D Cal 280,000 miles
'14 GLK 350 60000 miles

IIRC the fuel level wire is a single wire that starts at the top connector then loops under the lower part and returns to the top. There is another wire that simply runs top-to-bottom. The slider/fuel float "shorts" across the loop to decrease the resistance. The resistance increases as the level falls (a longer path for the current across the resistance wire).

Per the FSM 54-257; at full for sedans/coupes the resistance = 1.6 +/- 0.7; at reserve = 56.9 +/- 1.9 ohms. Measure at G and 31 on the sender.

Thanks for the reply. Im working on another car, not a mercedes. Its a bmw. One of the thin wires had snapped. I soldered another wire in place. Hope it works.

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'85 300D Cal 280,000 miles
'14 GLK 350 60000 miles

what kind of wire did you use?
OE is nichrome for it's resistance at length...

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

I didn't know there is a drain hole in the black plastic end cap. There is another drain hole (about 1/16" diameter) on the bottom of the aluminum tube/ housing.

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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

When I did mine I found one wire floating/snapped. I re soldered it back.....nerdishly carefully. (I'm good with soldering )

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

Just used a regular chrome looking wire for now. Will probably hit the junkyard this weekend.

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'85 300D Cal 280,000 miles
'14 GLK 350 60000 miles

It was too short to resolder.

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'85 300D Cal 280,000 miles
'14 GLK 350 60000 miles

So was mine....I slowly built a little solder tower and made it work.

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

I made tool for removing the nut holding the unit together.

First, I found a flat-head screwdriver that was narrow enough to fit inside the bottom.

I then took a dremel grinder and ground out the center of the screw driver wide enough to fit around the small center area on the sending unit. The screwdriver looks like it has two little legs on it. Worked great.

It is very important to get the two wires very clean, so I sprayed them numerous times, let them soak a little, and then very carefully, stroked the wires with two fingers until they shined. Anything that does not allow free movement inside will cause jerky movements on your gauge as the fuel level gets low. I used a green scotch pad to clean the outside, and like others said, make sure the hole in the bottom cover is really clean and fully open. It is important to get this very clean because any residual deposits will attract more gunk.l

curious..aside from the scotch pad..what did you use to clean the plate at the bottom? Mine is black and crusty. I'm thinking it isn't even possible to get it smooth and shiny. Also, I think this is the reason why my reserve light won't turn on. The crust is obstructing the circuit connection. Simple green? Let is soak? carb cleaner?

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1985 300d Turbo Diesel

I have cleaned 3 of these senders. once I had it apart, I used brake cleaner to blast the majority of the gunk, then used an Acid brush for the stubborn stuff.

Be very careful of the thin wires. what didn`t blast off with Brake Cleaner, i used a Kleenex with Brake Cleaner and wiped the wires.

For the tube spray it down and wipe with a clean rag to get the black stuff off. then the inside I used a long screwdriver to run a rag back and forth. then spray it down and let air dry, and assemble.



Charlie

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works