Fuel tank gate valve leaking

[Tator]

I've been trying to track down a small air leak in my fuel system. My fuel tanks have top feeds that are controlled by what appears to be gate valves. In pressuring the system, I discovered that I had a leak coming out of the packing nut on one of the valves. When I removed the packing nut I discovered that there was no sign of packing material. Is there a packless gate valve? Is it possible that it is some other type of valve? It would be a big PIA to replace the valve as it appears to be possibly epoxied into the opening and pickup tube. Plus it is not very accessible.

Thanks, Tator

 

[Ted]

Assuming you have the handle off try a little packing or a small "O" ring

Ted

 

[Giggitoni]

Do you have a photo? I wouldn’t use a gate valve in a fuel system. Try to replace it with a fuel-rated ball valve.

 

[syjos]

I've been trying to track down a small air leak in my fuel system. My fuel tanks have top feeds that are controlled by what appears to be gate valves. In pressuring the system, I discovered that I had a leak coming out of the packing nut on one of the valves. When I removed the packing nut I discovered that there was no sign of packing material. Is there a packless gate valve? Is it possible that it is some other type of valve? It would be a big PIA to replace the valve as it appears to be possibly epoxied into the opening and pickup tube. Plus it is not very accessible.

Thanks, Tator

Sandpiper is a Bluewater like yours. Do you have sumps at the bottom of the fuel tanks? Fittings in the sumps have valves or plugs?

I converted the fuel tanks to pick up fuel from the sump at the bottom of the tanks. Plugged the fittings at the top of the tanks. Many advantages to picking up fuel from the bottom.

As for the gate valve, do as Ted suggested and pack it with a diesel compatible washer or O ring. Buy several sizes and choose the one which fits snug and will seal the shaft when the nut is tightened.

A ball valve would be an ideal replacement except for the existing valves questionable installation. I have seen epoxy like JB Weld used to stop leaks around a fitting by applying an excessive amount of the putty to the joint.

I'm going to the boat tomorrow and will see what the OEM fitting consists of.

 

[rgano]

I saw this same type miserable excuse for a fuel installation on a Taiwan trawler long ago. Apparently the valves up high were allowing air ingestion which would of course stop the engines cold because some owner in the past had literally poured epoxy resin over them in an effort to seal them. Take Syjos' recommendation and convert to a bottom draw system. In the meanwhile, seal up that POS as best you can and never use a gate valve in your fuel system again.

 

[Tator]

Thanks all. Well aware of advantages of ball valves and bottom feeds. Either one would take a major effort. I was curious as to the valve design and the lack of packing. I don't have a sump on my tanks and very limited access to the valves. I did put in a vitron o-ring this afternoon which has seemed to stopped the drip when pressured up. However, my pressure gauge, which is part of my temporary installation, dropped off from 10psi to 0 in about 3 mins even after putting in the o-ring. I'll pressure up again in AM and soap the fittings looking for another leak (didn't see any other fuel leaks). The fuel may have all run back to the tank. It seems odd that the returns are ball valves, but not the feeds.

Tator

 

[Giggitoni]

Tank vent must be temporarily sealed. Otherwise, all your pressure will head that a way. Not sure of pressures used in testing tanks. Seems like I’ve heard 1.5 to 2 psi is enough depending on surface measurements of your tanks. Ten psi is ten pounds per square inch. For sake of discussion, if your tank has side walls measuring ten by ten inches each, or 100 square inches, you’d be exerting a force of 100 x 10 or 1,000 pounds. At that kind of pressure, you’d stand a chance of blowing out welds. Others, do I understand this correctly?

 

[Tator]

Giggitoni, You are correct on pressurizing the tanks. I'm not testing the tanks, just the valves and fittings. All valves are turned off. No need to block the vents. It takes about a 1/4 stroke on my tire pump to pressurize the lines and fittings.
Tator

 

[Giggitoni]

Got it! Thanks.