Calibration wire in hydrostatic fuel gauge?

[capt17]

Ok. So I am in the process of refurbing my gauge to a 1935 truck. I have read all the previous threads about it which has gotten me this far. A couple posts in these threads refer to a small calibration wire. My gauge shows no sign of such wire and all my diagrams don't show it. Where is it? What does it do? Can I reproduce one easily? The next step for me is to blow out the line with a bicycle pump and assemble. Thanks for the help!

 

[FlatheadTed]

Hi Capt,You can use a car pump as well .about 50 pumps .To activate the Gage you can blow in the flex pipe at the pump back to the tank or just rock the car or just drive it,To make the small calibration wire you cut some 1/16 bronze brazing/welding wire to 1"1/4 and drop it in the threaded hex tube ,depending how it performs you may need to shorten it .put 2 gal gas in ,fill the glass tube up to empty with the red liquid ,You can do this with Gage tied with string on the front of the dash .,blow through the 1/4 flex fuel pipe as you do it to get a reading .add more gas like 1/2 tank maybe 7 gal at that point it should be sitting on half full .I have done some other posts on this were I demonstrate how to clean out your glass tube etc, If you can find that thread there is maybe more detail .,

 

[TerryOH]

As mentioned the wire is in the hex storage tank for the red indicating fluid. Look inside the hex and you may see it. Don't bother trying to remove it if it is there. There isn't a lot of information regarding the wire, it is only my belief it acts somewhat like a brick in the toilet water closet. It displaces some of the fluid in storage and may help the fluid move from the storage to the glass section?? If the wire is not in place don't bother replacing it, the gauge should work without it. I have soaked the hex tank in liquid toilet bowl cleaner full strength overnight to clean out the old crud, it should climb into the glass section if the small connecting tube is clear of obstruction. flush with lots of clean water and blow dry before using. Read directions on the cleaner and follow since it is very harsh.

 

[capt17]

Thanks a lot guys! I have already used a lot of your previous posts to get me this far. The brake cleaner didn't touch the crud stuffed in the brass air tube and when I went to straighten it out, it actually snapped. Since I don't have another one of these laying around, I improvised two couplings from the old arrow connections from the existing system. I used a small piece of brass tubing from my rebuild kit and replaced the broken tube. Everything seems to be holding air tight so I think I might have pulled it off. I also did a lot of searching around the workbench and found the calibration wire. It must have fallen out and I didn't hear it. Hopefully the install goes well today!

Here's a picture of my soldering job.

 

[G.M.]

A measured amount of red fluid was was put in the gauge and a brass wire was inserted down in the threaded hex and cut to length to zero the gauge reading. The small brass tube needs to be soldered to the hex below where the new repair sleeve is installed, This is to keep the glass from breaking. PC-7 or JB Weld is put over the joint of the glass and tube to strengthen and seal them. If the calibration tube is removed or replaced put a small bend in it to hold in place. After soldering the tube to the hex cut the tube with a thin Xacto saw on the hex side above where it is was soldered. Run a thin wire from a paper parts tag and solvent through the tube into the glass to get the encrusted dried out red fluid out. Make a brass sleeve like a copper pipe coupling, tin both ends of the tube, put flux on and solder the sleeved joint. There should be enough solder from the tinning to solder it. To much solder will plug the tube. Blow through the glass and tube to make sure the tube is open. Fill the glass with red fluid to the ZERO mark. Pump your pointer finger up and down on the hex to raise the fluid to 1/4, 1/2 or 3/4 and hold your finger tight, the fluid should stay at that mark as long as you hold your finger tight. Keep the gauge vertical until installed. The test hose shown can be installed in the car to test the gauge, blow in the hose with your mouth WATCHING the gauge at all times so you don't blow the fluid out. Hold you tongue over the tube and the gauge will stay at where it was raised to. Blow through the air line from sender to gauge to make sure it is open. Check both ferrules to make sure they are soldered on these ferrules do not squeeze on to the tube. I also put a THIN coat of Permatex on the ferrules with a tooth pick to seal them good. Make sure all of the holes in the sender are open but do not enlarge them. Solder any cracked catcher cups or loose tubes and this will work like new. Put a rag over the filler neck and blowi into the tank to raise the gauge or bounce the car up and down or drive the car hitting brakes to pump air into the gauge. This type of gauge don't work when the ignition switch is turned on it needs air generated in the tank. G.M.

 

[capt17]

Success! (I think).

Hooked everything up today just as you guys described and I have a fuel reading, I have approximately 5 gallons in the truck tank and we are showing 1/4 full as the picture shows. Anyone know how many gallons at 1935 truck tank is? I blew into the gas line as some described and then filled to this point. I have yet to drive it because it has a Christmas tree in the back of it lit on display for visitors at our Fire Station. Thanks for the help! Now to figure out that vacuum wiper motor . . .

 

[FlatheadTed]

Wow Thats great ,well worth the effort ,I think 15 gal full for a car ?? The main thing is to make sure you have a good amount of gas in there when it shows empty