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tank sump o-ring

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drmax

Well Known Member
Hey ya fellas, a couple questions. I got a weeper on my right tank sump drain. I know the part num. is CAV-110. Can anyone give me the part number of just the o-ring or orings? It's leaking internal, and not from the threads. Also, what size of bolt threads into the tank, while I clean the old part, to plug the tank?

Is it worth to replace the entire assy, or just the o-ring? I'm creating an order from Spruce and want to get in on the way. Thx folks, DM
 
drmax said:
Hey ya fellas, a couple questions. I got a weeper on my right tank sump drain. I know the part num. is CAV-110. Can anyone give me the part number of just the o-ring or orings? It's leaking internal, and not from the threads. Also, what size of bolt threads into the tank, while I clean the old part, to plug the tank?

Is it worth to replace the entire assy, or just the o-ring? I'm creating an order from Spruce and want to get in on the way. Thx folks, DM
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You need a 1/8" NPT pipe plug (these are not bolt threads) and the plug is part of my flight kit in case an o-ring starts leaking while on a trip (it will happen). CAV-110 is the o-ring part #, $0.35 each from Vans or exchange a soft drink for an o-ring from a local A&P. :)
 
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Fuel Tank Quick Drain o-rings: MS29513-006.... This part I have saved from another post on VAF: (Viton o-rings from McMaster-Carr P/N 9464K11, size 008)
 
Unless it's really old it probably just has some debris in it which causes them to leak.
 
Get another drain, and a few spare O rings.

Carry them with you in the plane.

When you have a leaker, just switch out the drain complete with a new O ring in it.

Leave the fuel filler cap on, and there will be a minimum of mess with fuel leakage as you switch units.

Dont forget a bit of Gas Tite/Fuel Lube on the threads.
 
Walt said:
Unless it's really old it probably just has some debris in it which causes them to leak.
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Concurr! My slow drip disappeared once I flushed it a couple times by collecting a couple nice healthy fuel samples. Keep a couple o-rings handy in your x-cntry tool kit though.

erich
 
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fuel sump drains

FYI Saf-Air fuel drain valves are also available in STAINLESS STEEL, and eliminate the rust on the outside and on the inside (which will cause leaks). Just ask for CAV-110SS. Gene
 
Sam Buchanan said:
You need a 1/8" NPT pipe plug (these are not bolt threads) and the plug is part of my flight kit in case an o-ring starts leaking while on a trip (it will happen). CAV-110 is the o-ring part #, $0.35 each from Vans or exchange a soft drink for an o-ring from a local A&P. :)
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I'm lost....if it isn't a threaded plug, how does it stay in the tank? :confused:

CAV-110 is the part number for the assembly, not the oring. I'm looking for the oring part number and I'm thinking it is this...
MS29513-006. I'll grab some of these rings with a new drain, and some lube. Thx
 
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Mike S said:
Get another drain, and a few spare O rings.

Carry them with you in the plane.

When you have a leaker, just switch out the drain complete with a new O ring in it.

Leave the fuel filler cap on, and there will be a minimum of mess with fuel leakage as you switch units.

Dont forget a bit of Gas Tite/Fuel Lube on the threads.
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Ok, this is what I'll do. Where do you buy the GasTite product? A quick google search revealed notta. Thx Mike
 
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drmax said:
I'm lost....if it isn't a threaded plug, how does it stay in the tank? :confused
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it is threaded, it's just that the threads won't match any bolt you can buy. They are pipe (NPT) threads, hence the need for the plug, which will have the correct threads.
Erich
 
drmax said:
I'm lost....if it isn't a threaded plug, how does it stay in the tank? :confused:

CAV-110 is the part number for the assembly, not the oring. I'm looking for the oring part number and I'm thinking it is this...
MS29513-006. I'll grab some of these rings with a new drain, and some lube. Thx
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Correction: Vans part# for the o-ring is "CAV-110 O-RING". Their website is a little ambiguous.

Pipe threads are tapered whereas bolt threads are not. I used to carry a spare drain valve in the flight kit but now I just insert the pipe plug and fly it until I get home and have time to replace or clean the o-ring.
 
Sam Buchanan said:
Correction: Vans part# for the o-ring is "CAV-110 O-RING". Their website is a little ambiguous.

Pipe threads are tapered whereas bolt threads are not. I used to carry a spare drain valve in the flight kit but now I just insert the pipe plug and fly it until I get home and have time to replace or clean the o-ring.
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Sam, are there "2" orings? one internal to the assembly, and then one that mates the plug to the tank? Please advise
 
Only 1 o-ring on the valve. The valve seals to the tank by its tapered threads called pipe threads. Google "NPT Threads" to learn more. It gets tighter in the hole as you torque it more and more. Tapered threads need a lubricant to turn enough so that a good seal is formed, thus the recommendation for fuel lube, a fuel compatible pipe thread lubricant. Look up a product called "EZ Turn" at Aircraft Spruce.

The o-ring for the fuel drain valve, in viton material (ethanol compatible in addition to 100LL) can be found at McMaster Carr as part number 9464K11. They come in packs of 100, more than you could possibly use in a lifetime. PM me your contact info and I'll throw a few in an envelope no charge.
 
krw5927 said:
Only 1 o-ring on the valve. The valve seals to the tank by its tapered threads called pipe threads. Google "NPT Threads" to learn more. It gets tighter in the hole as you torque it more and more. Tapered threads need a lubricant to turn enough so that a good seal is formed, thus the recommendation for fuel lube, a fuel compatible pipe thread lubricant. Look up a product called "EZ Turn" at Aircraft Spruce.

The o-ring for the fuel drain valve, in viton material (ethanol compatible in addition to 100LL) can be found at McMaster Carr as part number 9464K11. They come in packs of 100, more than you could possibly use in a lifetime. PM me your contact info and I'll throw a few in an envelope no charge.
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Thankyou...nothing like getting some education! I see from here....
http://www.mcfarlane-aviation.com/pdfDocuments/SAF-AIR Product Catalog.pdf that the 110 don't have a surface seal, so I understand now how it works. I sorta thought a -6 seal that I listed, was too large. I'll just order some through spruce, and some sealant. I wanted to get a tube that I could carry in flyaway 1st aid kit. I saw that sealant from spruce and looked like a big containter. Maybe I could just put a finger full in an old medicine bottle and leave the big can behind.
 
Another RV pilot made a device that inserts into the drain and blows some air into it. I have seen that fix a slow leak that is probably due to a small piece of debris.

Open that fuel cap before using.

This reminds me that I need to get some of those O-rings and a NPT plug for my travel kit.
 
Spruce sells 2 quantities. The smaller quantity comes in a squeeze tube like toothpaste. More than you'll ever need but convenient.
 
krw5927 said:
Spruce sells 2 quantities. The smaller quantity comes in a squeeze tube like toothpaste. More than you'll ever need but convenient.
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Just seen that. Still getting used to Spruces ordering system. I'll pm you. Thx man
 
During quarterly condition inspection I replaced O-rings on both tank sump drains. The corrosion is caused by you know what. The same formula in the fuel helped to soften and considerably enlarge O-rings (old ring to the left). New ones are much harder. Let's see how long they last.










 
Vlad, the o-rings you pictured are NBR rubber, which have similar (lack of) ethanol resistance as the stock Buna N rubber o-rings. If you are using any fuel with ethanol, and I'm just assuming that's what caused your corrosion, a fluorocarbon material like Viton will fare much better in service. I bought a bunch from McMaster just for my fuel drains and would be happy to send you some without charge. PM if you're interested.
 
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