Does anyone know the chemistry of the float used in the early 107 models? I know later models used a series of wires, but the cross-section diagram I found for the unit installed in my model year showed a float inside the unit.
Reason I ask is because mine has been off since I got the car, but that's changing. When I first got it, a gauge showing empty meant I still had 9+ gallons left. That's slowly changed until now the gauge showing empty means I have ~5 gallons left. I'd assumed that the float had soaked up the gas and would always be off until I replaced it, but that doesn't seem to be the case. Anyone know what the float is made of? Maybe I don't have to replace the sending unit after all.
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When I die I want to go quietly, in my sleep, like Grandpa.
Not screaming, like the people in his car.
No, but I took apart two (the bottom has a nut you unscrew) 1980 450SL and 1978 450SLC. They were different inside but both had the same float. It was amazing. The float bobs up/down on a center rod. It has two arms that connect connect to a wire. This creates a variable resistor. More gas less resistance. Less gas, more resistance. I cleaned off the crud along the wires and rod (there was a lot) and mine started working after being stuck on "full" (it had sat for 4 years with a full tank of gas). At first it would sometimes read lower than I new was in the tank. I figured I had not clean well enough or the little arms were not making good contact. Recleaned, no problems.
Hope this helps. I can send a photo of the 1978 SLC if it would help.
Scott, I hope you don't mind me jumping in here. I have a simular probem with my gas guage. I was about to post and here I find yours. Any info or pics would be great.
Hope this helps. I can send a photo of the 1978 SLC if it would help.
Much help - thank you. Is the float a solid foam, or is it a hollow container? It might just be the wire that needs to be cleaned inside it. It sat for most of the 4 years previous to me getting it, so I'm sure the old gas fouled things.
My problem is more of a stability of the fuel guage. When I first got the car (2 weeks ago) the guage was OK until about 3/4 of a tank then the needle started bounce around and getting worse as the gas level fell. Once it got to about 3/8 the needle just stayed on E. Now the guage seems more stable until under a 1/2 then starts it's games.
Is my problem the same as Scott's a dirty sending unit?
Linear Mode
