How to repair a MB/GPW fuel gauge. Lots of pics

[Viking27]

Guys,

Can´t see the photos anymore, but might be because my connection is slow. Anyways, after reading this, I wanted to restore my original gauge, but now after taking it apart....its sadly to rusted away.......... RIP

Need a new (repro) or restorable original with long needle for early GPW. Any idea where I can get one? Most repros I see are with short needle.

Reg

[ElwoodJayBlues]

Just tried, Pics are still there.
Must be your connection.

Do you have pics of your rusted gauge?

[aamir567]

If fuel gauge does not show properly then one of the reason may be that the gauge in fuel tank is not working or not compatible.

[Jeepfreek]

hi.totally awesome.very well done and very informative.thanks jim.

[airsmart]

Mite want to consider the WW2 gauge has radium on the dial and numbers contact with the skin could cause skin cancer!!!!!!!!!!!!!!!!!! these gauges should be disposed of properly,I got this info from a WW2 vintage aircraft site.I read your post with great interest as I have a fuel gauge that needs repair,But I am concerned about a skin cancer popping up If some of the radium should get on me or be injested

[ElwoodJayBlues]

Good point,

but:

fuel gauge, amperemeter, temperature gauge, oil pressure gauge of a WWII jeep do NOT (NOT!!) have luminous dial markings or hands.!!
They're just painted white, no radium here! (See my pics)

Only the speedos have the point of the hand and two of the speed markings painted with radium.

EJB

[tamnalan]

Pics are still available? Alas, I can't get them to appear.

Alan

[tamnalan]

They're back! Thanks much!

[iowa]

VERY NICE ELWOOD!
copied all this info into my notes
thanks
dave

[Sean]

Hey Felix, excellent how to mate and pretty much what I do to a fuel gauge. One suggestion is while you have it apart give the case a clean and repaint along with the bezel. Instead of the earth wire inside the housing I tin the inside of the case and the brass flap on the gauge for a good earth contact and originality, also tin the middle of the back of the case and the end of the bracket spring. If you just sand it back to bare metal it won't be long before it is rusting again and earthing problems will start again.

How did you come to those resistance values.

I get a constant 34 to 36 ohms in this instance and the four Nos gauges I have are a constant 35 to 35.6 ohms.
Stewart Warner gauges register around 44 ohms.



The four Nos gauges I have all register between 48 to 51 ohms in this instance and my restored ones generally register
between 44 and 50 ohms.

[ElwoodJayBlues]

Hi Sean.

Thanks for your input!

Yes, just tinning the two components is better to keep originality.
But I wanted the safe way for my gauge.

I had a whole lot of gauges on my workbench during the last months and I've measured almost every resistance value one can imagine...

The four Nos gauges I have all register between 48 to 51 ohms in this instance and my restored ones generally register
between 44 and 50 ohms.

I think your value is more realistic...

[Steve Bump]

My gas gauge has all the right ohm readings after I took it apart and soldered up some of the broken wires inside, but it still just reads empty...so I want to know whether I can just hook one post up to my positive battery terminal and the other to the negative battery terminal to see whether it works or not. If I did this I think I would also need a ground from the case, is that right? I understand that the rest of the circuit could be a problem, but want to be sure that the gauge is functioning normally. What do you guys think?

Steve

[ElwoodJayBlues]

Is your tank and sending unit grounded properly?

EJB

[Steve Bump]

I believe so...I had a mechanic friend look it over and he said everything but the gauge was working, that the sending unit was working normally. He said that the gauge was the problem. For that reason I am trying to assess the gauge.

Given that my readings seem to fit yours, I am thinking the same thing I suspect that you are...that there is a problem elsewhere, but I wanted to know if there is a fairly simple way to test the gauge alone so that I know that it is good. If we establish how to do that, it may be helpful for all of us.

I have all the ground straps in place, including the one to ground the fuel line behind the air filter, the gauge should be well grounded (I sanded the edge of the gauge hole and cleaned that part of the gauge housing) but I also know that these things can be very sensitive...

Are there other things I need to do to ensure that my sending unit and tank are grounded? My next step is going to be to run a wire from the sending unit to a ground (did that before, but I think it was before I fixed my gauge). I appreciate your thoughts.

Steve

[Steve Bump]

With your help I have figured out a simple way to test the gauge to see that it works while putting it together. It would make sense to perform this test in addition to checking the ohms at each stage, given my own experience. Take a 1.5 V DC battery and connect the positive lead to the right post, and the negative lead to the left post (which goes to the sending unit on the jeep). The needle should deflect about ¾ full, as shown below:



Hope this helps someone. Unfortunately, just checking the resistances as described in this post was not entirely predictive of a functioning unit. My unit worked temporarily, long enough to get this pic, but when putting the bezel back on it stopped working (even after pulling it apart again). So my problem appears to be in the gauge rather than in the grounding and you can tell if that is the case for yours by this simple test above.

Steve