Hydrostatic fuel gauge problem

[Karl]

I installed the dual temperature gauge in my 34 over the weekend and its really nice to know what the temperature is of the motor. I think the gas gauge needs some fettling however . The old gas gauge would only read 1/2 full but would hold at that level and drop as it should with use. The new one was set up as suggested and I can blow it up to read correctly but that level is not maintained. Over 8 hours it drops down to read close to zero . A drive will bring it up but it doesn't stay up - I'm thinking slow air leak - Agree? Karl

[FlatheadTed]

Yes I would think a Air leak ,thread tap around the olive Ted1

[Karl]

Thanks Ted - since really the only think that I touched was the airline to gauge attachment I suspect that joint is the problem. The problem with putting a die over the thread is with the thermometer attached the gauge is a pain to get in and out - I might just resort to a little smear of silicone round the joints and see how we how we go with this . The car is lovely and as you described a real gem. When I installed the gauge I noted there are no thermostats installed. Original 193 4stats are probably pretty thin on the ground - My Model A has a 160 Thermostat welded to a pipe that fits nicely in the hose -worth using those? -Karl

http://www.snydersantiqueauto.com/thermostat-507

[FlatheadTed]

Hey Karl Glad you found the car as described ,Thread tap ,should have been thread tape ! Thermostats are quit a subject and has been discussed here at length ,I have done quit a bit of experimenting as have others here .This is just my opinion it can depend on the flow of the pumps and Radiator efficiency air flow ,Shroud ,6 blade verses 4 blade fan use a std thermostat with a bit of stainless pipe welded to it can work .if you have a radiator in very good shape it will likely work good but may need to be removed in summer ,depending on the other things . Ted 1

[32sedan]

Hi Ted. I just wanted to let you know that, even though I haven't posted to you before, you have helped me immensely! I 'm hoping you can do it again. I apologize if this seems like I'm highjacking. I'm tagging onto this thread because, frankly, I don't know how to start a new thread that is directed to you. In any event I think my issue is closely related to this current thread.

I have read your posts all over the site. As for the hydrostatic fuel gauge, it seems clear that not every one is plugged in the same way. I know that some people have had good luck cleaning them with toilet bowl cleaner, brake fluid, acetone, dish soap etc. None of them worked for me. I even soaked it in warm vinegar for days. Then I read your post where you said, if all else fails, I might have to straighten out the curly tube in the gauge itself and push a small wire thru. I thought that was a terrible idea b/c I was certain that the old brass tubing would break. But when nothing else worked, I did what you said and it worked perfectly! I was just slow and gentle with uncurling and curling the tube. That old gauge hadn't worked since I was a kid. It was a thrill to watch it come back to life.

However, I'm hoping you would have some insight about the fluid itself. I'm not sure that I like the fluid I used. I have tried two different 'brands' of the fluid - one from Macs and one from some other place whose name I can't remember. In both cases, it doesn't fade (I garage my car so there's no excess sunlight on it) but it seems like it evaporates. I did put the little felt plug and brass cap back in the back of the gauge but I think it still evaporates quicker than I would like. It's not an air leak i.e. It doesn't drop off overnight or even a few days. It's just that after a month or so, the gauge no longer reads the same when full (for example). Seems like it ought to be much longer between top-offs. Any suggestions? Is it actually a calibration issue? Seems like if it is correct for a while but then drifts after a month, it wouldn't be calibration. I don't want to use automatic transmission fluid like some suggest. I believe that would make the gauge go up and down but I bet it wouldn't be accurate. Help!

Thanks again for all of your participation in this site. This is the first time I have contacted you but I bet that I am only one of very many 'silent' beneficiaries of your expertise.

[Terry,OH]

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It does appear you have a small air leak. I believe you also have a problem with the sending unit upper cups, since they do not add to the air pressure sending the fuel level reading over 1/2 tank. Dirt in the tubes from the upper cups or even cracked solder joints Hard to remove but easy to fix.

[morrisgauge]

This instruction sheet may help in calibrating your gauge.