460 Fuel sender unit on the blink

fig

G-Wagen Club SA
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Mar 7, 2013
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Lindequesdrif
So my 1982 300GD fuel gauge stopped working after refilling the tank earlier this year.

When I removed the sender I found the resistor wire had broken, and one of the little stainless strips that hold the wire at the top was MIA inside the tank.

Thanks to Alan for the resistor wire. I replaced the missing strip with a piece of thin galvanised steel wire looped at the ends, because it was all I could come up with in a hurry. I fully expected to have to do it again, but the gauge is working now!

I did have to remove the sender a few times to get everything right. It's very sensitive about alignment and position of everything and the float got stuck at bottom. I also left a little tail on the resistor wire, which touched the fuel warning light wire and caused it to stay on all the time. I also had to replace the O-ring seal to the body, which didn't like being removed and replaced multiple times. Luckily I had an unused one from a new thermostat, which was the correct size.

Anyway, I eventually got everything positioned correctly and the gauge is now working properly, despite the bloudraad replacement for the little stainless hanging thingy.

Thanks for the resistor wire Alan!
 

fig

G-Wagen Club SA
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Mar 7, 2013
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481
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Lindequesdrif
Some feedback post my report above. Shortly after I posted, the fuel gauge needle started to swing about wildly with engine revs. The gauge still worked, but was only readable when stationary.

I figured my bloudraad repair was the problem and found some thin stainless steel to make a more accurate copy of the little stainless strips that hold the resistor wire. When I removed the sender and opened it up again I found that the resistor wire was quite loose, as I had been quite conservative when tensioning it prior to soldering.

I replaced the bloudraad with my fabricated stainless tab and then tensioned the wire until the copper hangers were under visible tension, then soldered it again. Back in the car, the fuel gauge now sits steady at all revs on the move.

I suspect the waving needle was caused more by the loose resistor wire than by replacing the bloudraad with a stainless strip. Something to think about for anyone who attempts this repair.
 

Gerhard van Rooyen

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G-Wagen Club SA
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Thanks for this feedback fig! I suspect my car's sender needs the same tensioning. I also replaced the resistor wire being very conservative with the tensioning of the scarce resistor wire (thanks Alan for sourcing) and the needle is jumping around a bit. At some point I will take it out and increase the tension a little.
 
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