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fuel tank drains

jask

Well Known Member
I have a fuel tank drain leaking. The new one from Spruce is brass. Is there any type of sealant used to prevent leaking after install?
 
Is it leaking around the threads , if so use a thread sealant. Most commonly they leak through the drain itself. If so you will need to drain your tank and remove the quick drain to replace the small o-ring. Usually it’s contamination that gets stuck on the o-ring that allows fuel to sneak past. I would also flush a bit of fuel into the tank with the drain removed to flush out any remaining contamination.
O-rings can be purchased from ACS .
 
I changed my leaking tank drain last week with a full tank.
Applied sealant to a new spare drain valve, sealed the tank vent with duck tape and quickly replaced the valve.
Lost about 1 - 2 oz of fuel in the process.
Don’t forget to remove the tape on the tank vent.
 
JD air

While you’re down there, I recently added the JD Air vents and drain covers.. works of art!
 

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Is it leaking around the threads , if so use a thread sealant. Most commonly they leak through the drain itself. If so you will need to drain your tank and remove the quick drain to replace the small o-ring. Usually it’s contamination that gets stuck on the o-ring that allows fuel to sneak past. I would also flush a bit of fuel into the tank with the drain removed to flush out any remaining contamination.
O-rings can be purchased from ACS .

No need to drain the tank or plug the vent. But you need to stand beside the leading edge of the wing while you quickly remove the old valve and insert the new valve or a 1/8" pipe plug. If you lie down under the wing.....you will be wearing fuel in your armpit for the rest of the day..... :D
 
I recently added wing root filters on my 14. I used a D cell battery powered transfer pump to pump out the fuel into a Mister funnel. I was surprised how much fuel I was able to remove through the filler cap hole. It didn’t take long to pump out and the last 2 to three gallons didn’t take long to drain through the quick drain. I think you would be able to get a better seal with everything dry than with fuel draining out. I know it’s doable, done it many times on large diesel tanks.
 
I agree with Sam. Don’t lay down. Just have new valve ready to go. Remove the leaky one and quickly place the new one with sealant on the threads. This allows any junk to flow out of the tank and u lose an ounce or 2, in a well placed bucket. Done in a minute.
 
Tie a rag or old tube sock around your wrist it’ll stop the dribble of fuel from running down your arm wile your swapping out the old valve with the new one or the 1/8” pipe plug to clean out or replace the “O” ring.
 
I had both wing fuel drains leaking a little. Mine are the SafAir CAV-110s. I know there's a rebuild possible with new O-rings, but the new CAV-110s were $15 each so I just replaced all three drains with new ones, rebuilt the old ones and threw them in the parts bin

Yes, you need a fuel-proof solvent, but readily available on Amazon. I used some LocTite 565 or 567 (can't remember). No issues.

I changed them out after removing all three and emptying the tanks for a new weight and balance, then re-filling each tank two gallons at a time to do fuel gauge re-calibration on a new EFIS install. Altogether, it was a bit of a tedious exercise but changing the drains was straightforward and cheap.
 
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A rag around your wrist is a good idea and I have done this more than once with fuel in the tank.
I use my fuel spill kit "bucket with sand" under the drain and accept the fact that I will loose a few ounces of fuel in the process.
I also ground the plane for this.
 
Two thumbs up

I changed my leaking tank drain last week with a full tank.
Applied sealant to a new spare drain valve, sealed the tank vent with duck tape and quickly replaced the valve.
Lost about 1 - 2 oz of fuel in the process.
Don’t forget to remove the tape on the tank vent.


O-rings

But MAC, if you need some I will send for only $5 each. :D

Permatex Aviation #3 sealant won't wash off unless using ethanol fuel.
 
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A quick fix for the o-ring leaking is while lightly pulling down on the plunger turn it several times in both directions. Sometimes that removes or dissolves whatever is under the o-ring. If it doesn't work then you're only our a few moments of time.
danny
 
O-rings

But MAC, if you need some I will send for only $5 each. :D

Thanks...I bought some from Spruce when I bought the new drains and installed the new O-rings on the old CAV-110s. The"rebuilt" drain valves now rattle around in my spare parts bin "just in case" :).
 
it shouldnt need any sealant NPT threads shouldnt leak on a new drain. you can put EZ-turn on them but i dont think its needed
 
I have a fuel tank drain leaking. The new one from Spruce is brass. Is there any type of sealant used to prevent leaking after install?

You can Check with Bruce Hill or ping me and I'll run down there to help out. I installed a "low-profile" fuel drain on my -10 and they are not rebuildable. They are cheap enough that I just swap them out if needed.

-Marc
 
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