Fuel selector leak

[flylow]

I have the Univair fuel selector and a fuel leak. I replaced the O-rings and still have a leak. It seems to be coming from the bottom of the fuel selector/ line to the gascolator.

I removed and installed a new Weatherhead 90° street elbow thinking maybe that was the culprit and the leak still exists.

It leaks when it’s in the off position. Is it time for a new fuel selector? Any advice?

Thanks

 

[skywagon8a]

Are there any tiny white specs of corrosion on the fuel line? Sometimes one tiny piece of corrosion eats through the aluminum fuel line causing an "invisible" annoying stain/leak.

 

[Steve Pierce]

Is the valve leaking external to the valve or internally through the line? If internally I would install new o'rings again and pay particular attention to the parts looking for trash or burrs. Installed new O'rings in plenty of things for them to leak or not work correctly only to work fine the second time. O'rings are cheap.

 

[flylow]

Are there any tiny white specs of corrosion on the fuel line? Sometimes one tiny piece of corrosion eats through the aluminum fuel line causing an "invisible" annoying stain/leak.

I don’t see any but I’ll double check!

 

[flylow]

Is the valve leaking external to the valve or internally through the line? If internally I would install new o'rings again and pay particular attention to the parts looking for trash or burrs. Installed new O'rings in plenty of things for them to leak or not work correctly only to work fine the second time. O'rings are cheap.

Well it’s -20 today and it’s outside. It looks like internally. I’ll try changing o-rings. They are cheap!

 

[Supertwotwo]

Did you replace the oring around the OFF closed port on the lower of this picture? If that oring is doing its job than no fuel can come out the bottom line even if the line is disconnected and hanging loose off the valve.

The oring is not on in this pic because I was drilling a new hole in the plug to make it a BOTH fuel valve instead of just Left and Right

 

[flylow]

Did you replace the oring around the OFF closed port on the lower of this picture? If that oring is doing its job than no fuel can come out the bottom line even if its off and not even connected to the valve.

I removed the fuel selector and found that the off position o-ring had a small tear from install. I made sure there were no burrs and cleaned everything good. It’s been 24 hours and no leaks.

Thanks for the great community encouragement. Thanks for all the replies and Steve Pierce for telling me to try it again. That’s exactly what I needed to do.

Here’s some helpful things I learned:



1. Part numbers
I have the Univair fuel selector. The small O-ring for the ports on the Univair is a -12. Others are -11. I was in a remote area of Alaska, ordered the parts and had them delivered from town. If you don’t know for sure which fuel selector, buy both -11 and -12.
MS29513-114 large (2)
MS29513-012 small Univair
MS29513-011 small Dakota Cub

2. Be careful with the brass Weatherhead fittings. They are soft at the opening and easy to crush. Ask me how I know

3. I decided to replace fuel drain valves while I had everything empty.
Flush valve F391-14
CAV-160 Saf Air fuel drain valve

4. Initially I had a plastic sleeve I cut/taped together to hold the springs and BBs in. After a few tries, I found it’s just as easy to reinstall without. I kept a large Ziploc bag under the fuel selector, installed the first spring and BBs and just held them in place. After sliding the first set in, I installed the second set and pushed them in.

5. Don’t forget EZ Turn fuel lube

6. It only takes 5 gallons or so to check for leaks. You can fuel up 5 gallons then check with the fuel selector.