Looking to buy a 300sd fuel sending unit

[ambiate]

I bought an 83 300sd last weekend. I had to fix every lock on every door, and the sunroof drains were plugged.. which resulted in mold all over the backseat.

After extensively tearing apart the interior, I decided to fix the fuel gauge issue by cleaning up the sending unit. After 2 days of struggling with channel locks, and hitting up 8 stores looking for the 44mm socket, I finally prevailed today.

Only to find out that my sending unit is completely shattered, there is no 'bottom' and the cylinder was kind of just hanging there. Completely blackened.

The copper wire and 2x silver wires were both still attached to the rod, and the weight too!

I wonder where the bottom piece and screw are at... oh well.

I need a new one, and the $200-300 price on ebay/amazon seems quite steep. Can anyone help me out? My local pick shops (75miles) do not have any Mercedes. I live in Waco, TX. I would gladly pay a reasonable price for an older one that still functions or somewhat functions.

Thanks!

Somewhat offtopic, but if I splice the wires for the Fan, I can get the air to come on. If I hit the AC buttons on the dash, nothing happens. I assume there is a relay somewhere that is burned out. The sunroof and most other buttons work, only the AC/Heat is unavailable. Any guidance?

[vstech]

wow, no MB's in waco? wild.
ANY 126/123 sedan sender will drop right in. gasser or diesel, same part.

I've got a few sitting on a shelf. but do a little shopping around and I bet you can find a mb yard near you.

[vstech]

oh, and welcome to the forum!

post some pics, and update your userCP with your location if you like!

[charmalu]

I just pulled a sending unit out of a 85 300D yesterday, $22 plus tax etc....
for my fuel tank swap project.

Wish I had seen this this morning, there is a 84 300SD and a 79 280CE in the yard.

I swaped in a 300D tank into a 82 240D, to up grade from 17G to 21G. there is a difference between the 2 sending units by 1 1/2 inch.

Charlie

[ambiate]

I absolutely love this place. It is a treasure trove of knowledge. I did not realize I posted this in the wrong subforum though, I apologize. I'm just so excited. This car is so modular and easy to work on. Everything just flows well. I'll try to call up some more places and see if I can find anything in Fort Worth or West Dallas. I was devastated when the sending unit was completely shattered. I thought it would be a quick fix.

I will definitely make a post for fixing malfunctioning manual locks later on, I took pictures of the whole situation and the one piece in the lock itself that was jammed. I have not attacked the vacuum system, but that should be my weekend adventure.

The help I've received here has been amazing! Thanks so much for all that you guys do.

I'm working on a twitter server for my networking class and have an algorithms exam tomorrow, but after that it's back to the car!

[vstech]

Originally Posted by charmalu

I just pulled a sending unit out of a 85 300D yesterday, $22 plus tax etc....
for my fuel tank swap project.

Wish I had seen this this morning, there is a 84 300SD and a 79 280CE in the yard.

I swaped in a 300D tank into a 82 240D, to up grade from 17G to 21G. there is a difference between the 2 sending units by 1 1/2 inch.

Charlie

oops, yes, it's true, the 240 sender is different... small tank, small sender, also the wagon sender is different as well, I THINK the coupe sender should be the same, but not positive.
if the wire is intact on your sender, you could pull the nut and cap and swap them to your sender if they are different

[charmalu]

I think it was the 240 that is longer. told my wife if I use it in the 21 gal (300D) tank, by the time the reserve light came on, you would be coasting to the side of the road.

Here is the diagram for the W123 vacuum system inter lock system.

W123 Vacuum InterLock Diagram

Charlie

[ambiate]

Hrm, I think I just connected some dots.

If the bottom of the fuel sending unit (bottom cap) and screws are in the bottom of the fuel tank, could that be what is creating the strong amount of pressure/sound after I open up the tank?

Thanks for the diagram.

[charmalu]

You are welcome.

No.

The pressure, or more than likely is vacuum and is sucking when the cap is removed. your tank vent is probably plugged. It is located under the car near the floor, and behind the L/R wheel. look for a little bell shaped thing pointed towards the ground, then a little plastic round thing, and a short piece of rubber hose connected to a metal pipe.

If the vent is totally plugged, the feed pump has enough oomph to suck in the sides of the tank.


The sending unit will have no effect with pressure/vacuum.
Charlie

[ambiate]

When I pulled the sending unit, it was in pieces.

The screw + rod + bobble + 3 wires were connected (somewhat).

The bottom piece that screws in is MIA. The screws are MIA.

The silver cylinder was loose and no longer connected, I had to dig it out, but luckily the unit kept it upright.

I am just unsure if the pieces are in the tank or if this is from the previous owner, haha!

[Yak]

There are a few current threads about sender cleaning. If the wires and the electrical contacts are in good shape, then you should just need the spirally looking plastic part, the disk and the nut. Any 123 sender in a JY ought to have those parts.

[whunter]

Originally Posted by vstech

wow, no MB's in waco? wild.
ANY 126 sedan sender will drop right in. gasser or diesel, same part.

I've got a few sitting on a shelf. but do a little shopping around and I bet you can find a mb yard near you.

Here is additional related information.
http://www.peachparts.com/shopforum/diy-links-parts-category/142399-fuel-delivery.html


.

[kerry]

this tool works on the SD also:

Alternative for 46mm socket on TD fuel sender

[SpecialDelivery]

welcome to the forum! I'm going to my pick n pull tomorrow, theres a couple of w126's over there, let me know if you still need the sending unit

as far as your AC goes, my friend is an automotive AC tech I will ask him for you

[ambiate]

I believe the AC has been pinned down to just the AC Control Unit being fried. I'm still looking for a sending unit! I was considering taking a road trip down to san antonio or houston, but I would much rather spend my break repairing the car.

I ripped the air filter out tonight. It looked 30 years old, completely black, crushed, moldy, etc. Went down to autozone and found a quick replacement and cleaned up the area and the ex-wasp family which used to live there.

Is there supposed to be a vent of some type of protection before the cold air intake reaches the actual filter? Something just seems like it needs a hack there.

After the air filter, I found the blown fuse that controlled my front window!

At this point, I'm looking at replacing the Fuel Sending Unit, Temperature Control Unit/Board, and one black Door Lock Knob.

The current plan is to do a diesel purge at fuel sender/receive tomorrow morning.
The next step is to locate the cause of the gas tank having suction and abnormal pressure.

I attempted to adjust my rack damper screw, but I could not get it to budge. I still have the original version.

I want to get a quote to replace the engine and transmission mounts. This one is out of my league, especially on campus.

The main priority is to conquer the vacuum system and find a tool to diagnose. I pulled a vac plug today which was extremely cramped and bent, but after testing all 3 outlets in combinations of two, I received pressure/sound from each.

Is there supposed to be a large empty space in the passenger/front of the hood? It serves as an excellent office desk, but I worry because that is typically the spot where the AC compressor hides in most modern cars.

Thanks again for the advice and help! I want this car to be my prized possession, but there is so much work to be done!

There is a pretty ruff transition from the first gear to the second gear, no matter what. Accelerating from 0-40 seems awkward, as opposed to 40-70.

At first, it sounded like the tranny was slipping, but the dynamics of this and the way it only happens from 1st to 2nd kind of throws me off. I'm going to check the trans fluid out tomorrow and make sure there are no debris from clutch material. I thought it could just be a result of the pressure in my gas tank from a clog. It could also be that bolt, because my 300sd can basically dance side to side in idle.

Another excellent night, I finished off the full exterior pull of the rear seats/upholstery and hand-toothbrushed the inner-chasis to ensure no molds/algaes/etc were growing. While annoying at first, the car actually smells normal now and the rear seat belts flow smoothly. The air filter (which looked like a 10 year old oil filter) was the biggest win of the day.