Diesel RVs: [diesel_mercedes] Mercedes Fuel Gauge Sender Service [14 Attachments]

[Attachment(s) from Nate included below]

O.K. , your fuel gauge doesn't work or the low fuel lamp doesn't come on or you're Nate and have been struggling with terrible fungus growing in the fuel that won't go away no matter what .

It's time to address the fuel gauge sender and here's how to do it at home cheaply and easily , co$t$ le$$ to buy the tools , take it apart and clean it than buying a new sender does .

Pic. # 1 shows the tool kit box removed and the LARGE water pump pliers you'll need unless you have a 46 MM (IIRC) socket handy .

You'll need to put your hands down inside the body's hole as shown in pic. # 2 , , one side of the water pump pliers will have a larger nut on them making it hard to grip the sender's hexagon , flip them over , get a good grip and pull firmly but slowly , the sender _will_ begin to slowly unscrew , once you get a 1/2 turn , it's easy to unscrew by hand , be aware it is FULL OF DIESEL FUEL so don't just yank it out as there's a tiny little drain hole on one side of it 2" up from the bottom so you have to watch for the thin stream of fuel pouring out and tip it so this fuel drains back into the tank ~ I like to fold up a LARGE clean old bath towel and lay it across the package tray just behind the top of the upper rear seat cushion , this helps catch the Diesel fuel you're sure to dribble no matter how careful you are .

Pic. # 3 shows the sender out of the car , notice it's black or brown , this is the fungus .Also is a bottle (I used two) of Isopropyl alcohol and a tall , narrow plastic water bottle , both from the .99 cents store .

Pic. # 4 ~ use some small water Pump Pliers to *gently* squeeze the brass nut and plastic on the very bottom of the tube to unscrew it and release the bottom cover and maze , the gooey black crud that also has chunks in it , is the dreaded fungus and it why your fuel treatments didn't quite kill it all off ~ it hides inside the sender tube .

Remove the bottom metal and plastic plates *gently* , then wriggle the aluminum tube off and peer in it , Pic. 5 shows a typical fungus filled tube , this wasn't touched at all .

Take the top and guts of the sender and ever so gently submerge it in a cheap water bottle filled with Isopropyl alcohol (picture 6) and take the delicate aluminum tube , soak a rag with more Isopropyl alcohol and gently run it through , like in Pic. # 7 twisting it as you go , when it comes out the tube should look like Pic. # 8 inside and out .

Pic. # 9 is what the sender should look like when you're through cleaning it ~ there are three delicate wires so be gentle , use a small soft bristle brush to work the alcohol into the fungus then wipe it off with clean rags or blow it clean with starting fluid (ether) in a foo-foo can .

Pic. # 10 , invert the sender on the open bottle of alcohol and carefully re assemble it , gently snug up the brass/plastic nut and you're ready to go back to the car .

Pic. # 11 shows one of the many places the special O-Ring might have fallen off (this one I found on the package tray,they also fall on top of / behind the fuel tank) ~ you CANNOT re assemble it sans the O-Ring ! .

climb in the back seat of the car and connect the harness plug then set the sender in the body hole so it hags more or less down , you'll hear the float inside the tube slide down and stop at the bottom ~ reach between the seats and turn the key on only until tge gauges come alive and the dash's warning lamps light , you should have a zero gauge and the low fuel lamp lit . Pic. # 12

It is ? good ! now , tip the sender up whilst watching the gauge and see how the low fuel lamp goes out and the gauge rises to the ' full ' mark . Pic. @ 13

Now you're ready to re install it , wipe the O-Ring and tank top and sender tube and threads clean with a clean lint free rag , place the sender into the tank and carefully screw it in by finger ~ if it doesn't easily screw in , STOP and back up , try it again , it should make several complete turns easily by your hands before snugging down into place .

Now , use the Water Pump Pliers to slowly but firmly snug it tight , not super tight here .

Last pic. shows the car running and the gauge working fine again . Pic. # 14 .

With this 21 gallon tank in my 1981 W-123 240D , I have 153 miles on it and still shows 1/2 tank of fuel ~ I think I'm going to like this modification very much .

-Nate

DCG Whse.

Your Tax Dollars at work !

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