Redoing my hydrostatic fuel gauge with new red liquid

[JimG]

I had redone my hydrostatic fuel gauge on my 34 in 2017, using red fluid from Classic and Exotic. In a few years, the red color faded even though the car is always kept in a garage, and I also had some white deposits showing up in the gauge, so I decided it was time to redo it. I thought I would post my experiences to help anyone else who wants to do this.

I bought two vials of red liquid from another source last year. I don't remember who I got it from, it seemed like he was a private individual that I may have read about on the barn or some other website like a Packard site. He claimed to have liquid that would not fade, and had only a few vials left. It was a good thing I bought two vials, as by the time they arrived, they had leaked inside the box on shipping so each was only about half full.

When I redid the gauge in 2017, I had soaked it in rust 911 and then painted the rusty inside of the gauge, so it was still in pretty good shape. The first time I did the gauge, it would only come up to about 5/8 to 1/2 when it was full. Went pretty much to empty when empty.

Cleaning up the gauge, I found the tube was dirty and the reservoir had some white powdery stuff in it. I use some brushes in a kit I had on hand from Harbor freight to clean these. The smallest brush fit perfectly in the glass tube and the next side up fit the gauge reservoir. I put a small piece of white cardboard behind the glass tube - just like it had when I originally disassembled it. I used a small piece of teflon tape on the threads of the reservoir.

I had read about how to adjust the level in this thread:

https://www.fordbarn.com/forum/showt...ht=hydrostatic

It said that to adjust the level, you add rods to the reservoir of the gauge - I believe this is to reduce the volume of the liquid in the gauge, so the pressure from the tank has less fluid to support and and this raises the liquid level. No one seemed to be very precise about how much to add, although the reference thread has some calculations. My gauge had one rod in it that was stuck inside. It also had a lot of white powdery residue in the reservoir. I soaked the gauge in lime away for a while and then used a small screw to grab the rod and pull it out. Once I had the rod out, I cleaned the rod up with steel wool and found it was brass, and about the diameter of a 12 ga wire. Since that rod only got the gauge up to half way when full, I bought a 1/8" diameter brass rod at Lowes ($3.80 for a 3 ft piece) and installed the gauge with a 2" long piece in the reservoir. It was larger then the old rod, but not hugely larger. I set the red liquid level at empty with the 1/8" rod in place and installed the gauge. I use a syringe to put the liquid in, as this also let me withdraw liquid if I got it too high. Test drives with the tank pretty empty looked somewhat promising, although the gauge was showing about 1/4 and seemed to go up and down a lot while driving. I went to the gas station and filled the tank and that blew the fluid out of the gauge. So the 1/8" rod was too large. Lost some of my scarce fluid on that attempt.

After that, I decided I needed to be careful as I had a limited amount of red fluid and approach things sort of like a science project - one change at a time and observe results during a test drive. After removing the gauge and cleaning everything up, I reinstalled the original rod in the reservoir and reinstalled everything. This test drive had the full tank level showing at about 1/2 - which is what this rod used to show previously - so I was back to where I used to be level wise, but with new red fluid, and proved that I had repeatability from what I had done 5 years earlier.

Now realizing that these gauges seem to be pretty touchy, I decided to try adding 24 ga brass wire I had on hand, one wire at a time, and test after each installation. So I took the air line off the gauge and added one 2" long piece of 24 ga brass wire as an addition to the original brass rod. Another test drive and this time the gauge went right up to full. So this shows how touchy these gauges are. One piece of 24 ga wire was enough to raise the full level from 1/2 to full. This is the type of information I could not find in any previous threads I looked at on adjusting the level of these King-Seeley gauges.

I would also mention that the test drive doesn't need to be long - but it does help to be on a bumpy road. Just a short drive on a bumpy road seemed to be enough to get the gauge to go to it's max level.

Here are photos of the tools I used and my final gauge position during the last test drive. We will see where the level goes after I drive the car more, but this looks pretty encouraging. I have read that other people have had trouble getting their gauges to more than 1/2 or so when full, so I thought I would relate the results of my science experiment. We will also see how long my new fluid stays red.