[January 18, 2007]

Tonight I wanted to leak test my right tank. I was a bit nervous about this; mostly scared of what I would find and where the leaks could be. My biggest concern is that I wasn't doing something right from the getgo and there would be leaks galore.

I have Van's leak test kit which contains a handy adapter that allows you to pump air into your tank with a bicycle pump in the tank drain port. It also comes with a plug for the fuel line. In the instructions they recommended to use either a balloon or a manometer to keep pressure in the tank - about 1 psi. I didn't like the balloon test because it could play tricks on you. You could think it got bigger or smaller. Also, balloons are thin skinned rubber things that leak air on their own -- how many times have you tried to save birthday balloons when you were small only to find them limp and on the ground the next day? So using a manometer was what I was going to do. All I needed was some tubing and a way to hook it onto the tank, so I went shopping today for some vinyl hose at Home Depot.

So I have everythign I need to do the tank test - adapter for the fuel outlet to the vinyl hose, plugs for the vent and the fuel return, the schraeder valve adapter and some EZ Turn. I buttered up the o-ring and the bicycle pump adapter with the EZ Turn. I made the mistake of putting it on my bare finger and applying it. This stuff was NASTY to get off of my fingers. I should of used a glove.

This was my adapter for the hose. I didn't like the idea of clamping the hose to the elbow fitting, for fear of a leak developing there. So with leftover parts I made this nifty adapter. I used two clamps just because I could.

Next I fitted everything to the tank and filled up the tubing with some colored water. I used blue die only because that is the same color as the carpet in the basement - an accidental spill would go unnoticed. So I filled up the tubing with water. Then I pumped air into the tank. Then I filled the tube up some more with water, then more air. Basically an iterative process until I measures 27" between the two water levels.

All of the fittings on the tank.

This was the initial water level. You can kind of make out the marking I made with a sharpie.

After about 30 minutes, the water rose about 1/4"

After 2 hours, the water rose 5/8"! Since the basement temperature was fairly constant, I couldn't figure out why the water was rising. Then it came to me. There is a storm coming tonight and the barometric pressure is probably dropping. I went to weather.com and backup up my theory. Sure enough the pressure dropped. I thought it would be neat to mathematically prove the relationship between the barometer change and the change in the water level. Sure enough it can't be that hard - we know the volume of the gas tank, the area of the tube and the amount that the water moved. But then again who cares. It is pretty clear that I have a LEAK FREE TANK!

Finally I did some final prep work on the left tank - mounted and safety wired the pickup tube, bent the vent tube and checked all of the countersunk rivets holes on the skins.


Last Modified: September 4, 2017