Check the DIY section, I think there's a write up about it.

Seems to me, there's a weird screw on the bottom of it, a 2 part head to it. I happened to have had an upholsterer's screwdriver, which sort of has a notch cut out in the middle, which is what you really need, or you can get a wide screwdriver and cut out a notch. The screwdriver, from memory, has to spin around, without affecting the area or rod in the middle, which is why it has to be notched.

This is all a very easy fix. You take the rod out, and it's probably a bit rusted up, mainly from the tank not getting filled up for very long periods of time (a car that's sat for 2 years for example, or only got $3 of fuel at a whack). Without the tank being filled up, the float doesn't go up and down over the rod, and it eventually rusts.

The hardest part, is trying to read what to do, trying to understand it, then doing it. By the time you're done, you'll say, wow, that was easy!

jeff 1991 300d

added for reference

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1985 300TD Turbo Diesel Wagon
273,000 miles

Yes correct I can't see the wood for the trees it is here

http://www.peachparts.com/Wikka/W123FuelSender

I wanted to make sure that I had got the sender unit as clean as I could. I bought a set of security bits that had several two pronged driver ends and took the little screw at the bottom of the sender off.



Here you can see that even just under the bottom washer there is a load of crud that unfortunately could not be shifted other than by disassembly.

Here the outer casing is being pulled from the end with the electrical plug



You can clearly see the three delicate wires...

And here is a picture looking down the tube. Muck.



And this one is showing how much muck I had to scrape out of the bottom.



It is all cleaned out now and back together. It really is a 10 minute job.

Question: how hard is it to get the plastic disk off the bottom once you've removed the slotted nut? On my 240D fuel sender the plastic bottom just seems to be stuck tight to the aluminum tube... should I use channel-lock pliers to gently persuade it to let go of the tube by pulling in the long axis of the tube? Or try rotating the plastic bottom with the channel-locks, as a prelude to pulling it off entirely? Or I wonder if I need to start the cleaning process by shooting solvent into the hole where the nut came from, on the theory that the gunk that is holding the plate in place is anchored to the threads of the inner rod?

Cheers,

Kurt

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- '79 240D - engine swap complete! Engine broken in! 28-31 mpg! Lovin' the ride!
- '86 190D (W201-126) - 2.5 NA engine, 5 speed, cloth interior, manual climate controls, 33-34 mpg (sold to forum member).

In homage to the magazine cover: "Do you feel lucky, punk?"

When I cleaned mine I didn't realize the plastic base disassembled. I removed the nut, slid off the tube with the bottom intact and stuck together, then was surprised when it all fell apart. Try removing the tube + bottom from the top. Less gunk and crud cementing the top together.

Look at what awaited me. That's some serious gunk.

Kurt

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- '79 240D - engine swap complete! Engine broken in! 28-31 mpg! Lovin' the ride!
- '86 190D (W201-126) - 2.5 NA engine, 5 speed, cloth interior, manual climate controls, 33-34 mpg (sold to forum member).

Wow I'm impressed - you're the leader in the grottiest float competition!

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Does anyone have a diagram or know what wires get connected to which terminal on a 1980 300TD sending unit? I took mine out to clean and the connector fell apart. I tried to put them on where I thought they were, but now the gauge doesn't work at all. If I touch the unit to the side of the hole it will spike the gauge up to full. I'm thinking I have the ground wire connected to the wrong terminal. The reserve light now works though. Any help would be appreciated.

The Brown wire is your ground.

Blue/Green wire is for the low fuel indicator.

Blue/Black wire is for the Fuel gauge sender.

This is as per my Electrical Trouble Shooting FSM 83-85 model yr.

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

Same for my 123.130 non turbo from what I can make out from those rat nest diagrams!

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

thanks

FYI on wagons, there's a resistor to compensate for the fuel tank shape. The basic colors are the same, but it looks like the fuel level wire connects to pin 4 for the wagon, pin 1 for sedans and coupes. I posted a pic of the drawing from section 47 of the FSM in his other thread. It makes it clearer. 4 is unused on the sedan/coupe.

Wire functions by color are the same in sedans/coupes/wagons.

I just readjusted everything and the fuel gauge still reads empty. If I touch it to the "T" it pegs at full. If I touch the blue/Green wire to the "T" terminal the reserve light comes on so the "t" would be the ground. I attached the brown wire to it and then the Blue/green wire to the "W" and the blue/black wire to the "G". The blue/black wire also has a resistor going off of it to another plug, but there are only 3 terminals on the sender for 4 plugs.

The guage worked perfectly fine before I disassembled the sending unit, but the reserve light didn't. i cleaned it out really good. Now the gauge doesn't register at all and the reserve light works. What could I have done wrong?

If you have a G, a W, and a T on the sending unit, I would assume these correspond to the markings G, W, and 31 from the pdf of the tank in the other thread.

31 = T, and that's brown
W = W and that's the warning light, so should be blue/green
G = G for the guage and that should be blue/black.

Because the shape of the TD tank is different, it has the added resistor. The gauge basically measures the length of the resistance wire. As the float sinks, the amount of wire seen by the gauge gets longer. In the wagon, they add the resistor to simulate some extra length due to the shorter tube. You want to hook the very end of the blue black wire+resistor to the G pin, then make sure the other pin is out of the way. This puts the additional resistance back into the circuit

Do you have a multimeter and know how to use it to read resistance? If so, measure across terminals T and G. At full the wagon should read 3.2 ohms, at empty 52.2.

If it reads infinite, then you broke the resistance wire while cleaning it. That's bad.

If it reads correctly, but the gauge indicates empty, that probably means the contacts inside the float aren't touching the wires. You may be able to squeeze them tighter.

Check your PMs.