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Tank seal or O-ring?


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Dear all.
Anybody an idea whether the stains in the marked area also originate from the obviously leaky valve drain port or rather from a broken sealant inside the tank?
 
Greets from Germany
 
Martin
749BDD38-CDAB-4F83-B775-3DCC3C4D78D1.thumb.jpeg.0eda28b47b1d104593b11e0df699aae5.jpeg


I agree. Change out the fuel drain first. I saw a lot of fuel around mine and when I changed it out, it stopped the leak. The drains are not that expensive.

e36f9e10024fa4afee090a07d1e91bbe.jpg


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To me, looks like Fuel is or was coming from sump drain as well as the inspection panel screw. Just wipe off the fresh blue stain from the screw and see how long it takes to return. Still worst case fix isn't a reseal but just a re-seal of the leaky screw - but see how long it takes to stain - since it looks very minor. 

Personally I'd clean the area real well around the sump drain first and see how long it takes to blue stain as well. Its so dirty there you can't really tell if that is fresh stain or not. A bit of avgas on a towel will easily clean it up. If and when replacing a sump drain be very careful to not overly torque it, (follow your MM instructions) doing so will create a much worse leak :(

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Hey Martin!

Looks like you have both solutions that you are asking about...

1) Inspection panel screw leaks are pretty common... easy to fix... might start with a new screw and clean threads to improve the ability to fix it once....

2) Drain sumps don’t last forever... the rubber seal is often carved into the head of the drain device... a very light torque holds it in place... anything more snaps it off in the hole.... expect that there are two seals internal and external...
 

Make sure you get the proper drain device for your plane... there are several versions... that look similar... As you can see in the pics by Marauder... there Can be a difference in height of the drain holes.... The height of theses holes from the sealing surface dictates how much water gets left in the tank, after draining...

Some Mooneys have a different internal tank structure that these drain holes have to be above... the holes need to be above the structure to allow the Fuel/water out...

This is a great first fuel leak project... high probability of quick success... :)
 

Pp thoughts only, not a mechanic...

Best regards,

-a-

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15 hours ago, ArtVandelay said:


Is there suppose to be a rubber gasket on them?

Deleted because I am not Clarence.  Great photo below with part number.  My question is: Does the valve change for different vintage planes based on tank size/configuration?  Is this the valve for WHAT models of Mooney’s or ALL Mooney’s?

 

Edited by Missile=Awesome
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Martin,

Clean the area with Acetone or some nail polish remover borrowed from your wife, it will remove the old stains.  Roll some toilet tissue into a point and use it to dab around the area to find the source of the leak.  Sometimes very small amounts of fuel are hard to see on white paint, tissue paper helps.

The O ring under the valve is normally an MS29513-014, the valve is an F391-53S. Drain valve torque is 40-65 inch pounds, from SB M20-188

The valve on the left is the correct one, the Center is the nut which is in the wing tank, the valve on the right is the wrong one.

Clarence

FB5E3A0D-3F19-403D-A73F-D1D90A154EB2.jpeg

Edited by M20Doc
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If you ever want to “rebuild” one, the kit consists of two o rings and new clip. Like others mentioned, I do not think the o rings in the kit are even Viton which is mindblowing considering the price of the kit. Maybe our [mention]OSUAV8TER [/mention] friend can compete with a similar kit that uses Viton.

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3 hours ago, M20Doc said:

Martin,

Clean the area with Acetone or some nail polish remover borrowed from your wife, it will remove the old stains.  Roll some toilet tissue into a point and use it to dab around the area to find the source of the leak.  Sometimes very small amounts of fuel are hard to see on white paint, tissue paper helps.

The O ring under the valve is normally an MS29513-014, the valve is an F391-53S. Drain valve torque is 40-65 inch pounds, from SB M20-188

The valve on the left is the correct one, the Center is the nut which is in the wing tank, the valve on the right is the wrong one.

Clarence

FB5E3A0D-3F19-403D-A73F-D1D90A154EB2.jpeg

O.K. What is the first valve that was shown Clarence?  Is that a valve for a vintage Pre-J Mooney?  I replaced valves on ‘66 and that valve did NOT have the rubber gasket as shown in these photos.  This is great information. Thank you.

Edited by Missile=Awesome
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7 minutes ago, Missile=Awesome said:

O.K. What is the first valve that was shown Clarence?  Is that a valve for a vintage Pre-J Mooney?  I replaced valves on ‘66 and that valve did NOT have the rubber gasket as shown in these photos.  This is great information. Thank you.

Check the IPC (parts catalog) It shows just what is pictured here-  a drain valve and an O-ring just as he describes. 

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49 minutes ago, cliffy said:

Check the IPC (parts catalog) It shows just what is pictured here-  a drain valve and an O-ring just as he describes. 

Good point on checking the parts catalog. And for reference, the drain pictures I provided above are the aftermarket drains for the O&N bladder system. 

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2 hours ago, cliffy said:

Check the IPC (parts catalog) It shows just what is pictured here-  a drain valve and an O-ring just as he describes. 

Cliffey, My question has NOT been answered.  The original poster didn’t identify what model his plane was.  NOT every owner has a parts catalog for their model...That’s why they come to Mooneyspace with a question.  

1. The first valve (after later clarification) photo is for a bladder on ? Mooney models.

2. Second (Left valve) is for what Model and tank capacity?

This stuff can make a huge difference when you are trying to get the “right” part.  My take away is that parts diagrams on line often don’t have good detail and get me a clear “answer” to my question.  Second take-away, Parts guys at Mooney Service Centers are invaluable.

Thanks for your reply.

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I recently replaced a drain valve in my 1975 M20C with bladder tanks.  I think the number was F391-18.  Looks very similar to the left valve in the first picture.  I asked Griggs for the number before finding it listed on the drawing.  While talking with him, I looked the number up on the Aircraft Spruce site.  Asked about the O-ring and he said it used no O-ring like the picture at Spruce. Then I realized the -18 was the 1/8" NPT that seals on the threads, not by O-ring.  Not much taper on the 1/8", I didn't even notice.  In the end, check you part numbers every time.

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6 hours ago, Missile=Awesome said:

O.K. What is the first valve that was shown Clarence?  Is that a valve for a vintage Pre-J Mooney?  I replaced valves on ‘66 and that valve did NOT have the rubber gasket as shown in these photos.  This is great information. Thank you.

The left valve is the standard valve used on all models, other than early one’s.  Early models had riveted valves which are no longer available and are replaced with SB M20-188 kit, which are also getting harder to find.

Clarence

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7 hours ago, tigers2007 said:

If you ever want to “rebuild” one, the kit consists of two o rings and new clip. Like others mentioned, I do not think the o rings in the kit are even Viton which is mindblowing considering the price of the kit. Maybe our [mention]OSUAV8TER [/mention] friend can compete with a similar kit that uses Viton.

There is no rebuilding of these valves, they were never meant to be repaired.  Note that the upper end is pinched closed, if you try to un-pinch it, it will crack.

Clarence

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There is no rebuilding of these valves, they were never meant to be repaired.  Note that the upper end is pinched closed, if you try to un-pinch it, it will crack.
Clarence

But there is a “seal kit” for $3.
be3b48da81d5e56819e3c79f3880bf4b.jpg
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Just now, M20Doc said:

I don’t see how you’d use that kit on an F391-53S as used in a Mooney?

Clarence

That is correct. Its for a SA18 valve. I just read McFarlane's web site and the kit actually does come with a Viton o-ring. My bladders have the SA18 valve.

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Wagaero sells a kit for the S53 valve. I just replaced mine. They come with 2 orings and the new c clip. When I disassembled mine I found the clip was not installed properly internally from safe-air. :-0
I just bought a few extra kits to have on hand.

-Matt

 

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