Gas guage - PeachParts Mercedes-Benz Forum

Slow Joe · #1 08-21-2012, 11:02 PM

I have an 86 300E with a broken gas guage. It does not bounce around, like I have read about. It doesn't do much of anything. It moves between 3\4 empty and 5\8 empty when it's full. The reserve light comes on so I know when to fill up. Any suggestions on how to fix this?

bunksbbq · #2 08-21-2012, 11:27 PM

The float is sticking, probably due to buildup on the strut or wires that it runs along as the tank fills/empties. You can remove the guage from the top of the tank and carefully open the tube to access the wires and float. I used a large pipe wrench to take off the collar. The tube is opened by a small nut at the bottom of the guage. You have to be very careful taking it apart, the wires themselves are very thin and can easily break. Once apart, with care clean the middle pole that the float runs on. Don't try to clean the wires, they will break if you touch them, guarenteed. If all goes according, you should be able to get it back to working. If you should break a wire they can be replaced. I was able to source the sending wire as 42 guage nichrome wire, iirc. The second wire is just for the warning light and is regular fine wire. Good luck

Slow Joe · #3 08-22-2012, 12:12 AM

Thanks! I'll check it out in the morning.
Where is the gas tank?

JK..thanks

bunksbbq · #4 08-22-2012, 12:48 AM

In the trunk, behind a carpet covered board at the back that just pulls away. The sending unit is at the top of the tank in the middle. There is a plug with wires attached. When you remove the collar, be careful with the large o-ring. You may get away with reusing it. You have to lift the sending unit up and then tilt toward you to remove and clear the bottom of the speaker deck. Sometimes, as was the case with my '91, the deck is too low and you will have to go to plan B which is to pull the tank. If that is the case, I would get a new sending unit altogether and not waste the effort of doing what is really just a bandaid for now. Pulling the tank is a bear of a job and one you only want to do once. If you are lucky and it comes right out, it pretty easy to fix.