Fuel Drain Valve for 63 C model

[Greg Ellis]

I need to replace the right wing fuel tank drain valve on my 63 C model.  I read on an older thread that the valve for a 75 F model is F-391-53S.  Is it the same for a 63 C model or is there a different part number?  Thanks in advance.

[47U]

44 minutes ago, Greg Ellis said:

Is it the same for a 63 C model or is there a different part number?

Yes, the same.  Provided the below SB has been accomplished.

https://www.mooney.com/wp-content/uploads/2020/12/SBM20-188A.pdf

[Greg Ellis]

3 minutes ago, 47U said:

Yes, the same.  Provided the below SB has been accomplished.

https://www.mooney.com/wp-content/uploads/2020/12/SBM20-188A.pdf

Thank you.

[carusoam]

On 4/2/2023 at 10:24 AM, Greg Ellis said:

Thank you.

If you haven’t changed one of these before…

Know the torque for the valve…

Its probably in inch-lbs…

It is really easy to destroy the new valve if you use a typical socket wrench that matches the size of the valve….  

Then the drip has been eliminated… now it’s a torrent!

M20C owner that misunderstood the guidance of the mechanic that handed him the part….  
 

Best regards,

-a-

[Greg Ellis]

4 hours ago, carusoam said:

If you haven’t changed one of these before…

Know the torque for the valve…

Its probably in inch-lbs…

It is really easy to destroy the new valve if you use a typical socket wrench that matches the size of the valve….  

Then the drip has been eliminated… now it’s a torrent!

M20C owner that misunderstood the guidance of the mechanic that handed him the part….  
 

Best regards,

-a-

Thanks for the advice.  I am leaving this one up to my mechanic. 

[Guest]

10 hours ago, Greg Ellis said:

Thanks for the advice.  I am leaving this one up to my mechanic. 

Much depends on wether yours has been updated or not.  If you have an external hex nut, it’s updated.  The one on the left is the correct valve for a Mooney.  The one on the right is from a Cessna and while it threads in, it’s wrong.

[carusoam]

Note the drain hole at the bottom of the tank… not an inch high.

the extra height would accidentally keep a lot of water from draining properly….

Best regards,

-a-

[Greg Ellis]

Thanks.

[Greg Ellis]

13 hours ago, M20Doc said:

Much depends on wether yours has been updated or not.  If you have an external hex nut, it’s updated.  The one on the left is the correct valve for a Mooney.  The one on the right is from a Cessna and while it threads in, it’s wrong.

Thank you.

[Greg Ellis]

Question: When replacing the drain valve, is it absolutely necessary to drain the tank first or do you just have to be quick with your thumb to plug the hole after removing the one drain and quick again putting the new one in?

Also, if there is a small amount of stain around one of the screws in a inspection panel of the fuel tank, I have read that it is possible to remove the screw, add some sealant to it and put it back in place.  If so, is it necessary to drain the fuel with this procedure and do you use the same sealant as is usually used inside the tanks?  Sounds like a stupid question but I need to get the right sealant to do the job.  I have developed two small leaks, one from the drain and one from around one screw and I want to be armed with enough information to communicate with the mechanic that will be doing the work.  Thanks.

[EricJ]

15 minutes ago, Greg Ellis said:

Question: When replacing the drain valve, is it absolutely necessary to drain the tank first or do you just have to be quick with your thumb to plug the hole after removing the one drain and quick again putting the new one in?

Every time I've done it (maybe three or four times), I've just plugged the hole with my thumb.    My previous IA warned me not to do it with a full tank since the added pressure can make it worse, and I don't think I've ever done it with a full tank.  Naturally, the lower the better.  Just be prepared that there'll be some spillage, it's probably going to go down your arm (so don't wear long sleeves), and be ready to make the swap once the old one comes out.

I once spent quite a while under the wing with my thumb on the hole while @N201MKTurbo tried to do a bench repair on one of my drain plugs that was leaking.   It can be done. 

Doing it in a well-ventilated area with a fire bottle handy is a good idea.

[Fly Boomer]

17 minutes ago, EricJ said:

Doing it in a well-ventilated area with a fire bottle handy is a good idea.

[47U]

33 minutes ago, Greg Ellis said:

Also, if there is a small amount of stain around one of the screws in a inspection panel of the fuel tank,

Is the inspection panel on top of the wing or bottom of the wing?  

[Fly Boomer]

37 minutes ago, Greg Ellis said:

If so, is it necessary to drain the fuel with this procedure and do you use the same sealant as is usually used inside the tanks?

Usually CS-3330.

[EricJ]

2 minutes ago, 47U said:

Is the inspection panel on top of the wing or bottom of the wing?  

There are multiple panels on the top and the bottom.

[EricJ]

43 minutes ago, Greg Ellis said:

Also, if there is a small amount of stain around one of the screws in a inspection panel of the fuel tank, I have read that it is possible to remove the screw, add some sealant to it and put it back in place.  If so, is it necessary to drain the fuel with this procedure and do you use the same sealant as is usually used inside the tanks?  Sounds like a stupid question but I need to get the right sealant to do the job.  I have developed two small leaks, one from the drain and one from around one screw and I want to be armed with enough information to communicate with the mechanic that will be doing the work.  Thanks.

Permatex 3 can be used on the screws.    If the plastic cap behind the screw isn't broken apart the screw can be removed without creating a larger leak.    It's probably worth being careful on the bottom ones in case the plastic cover is broken inside, but it's pretty easy on the top ones.    It's a good idea to dig the old crap out of the screw hole before putting the screw back with new sealant, to help keep from breaking the cap if it isn't broken already.

[Greg Ellis]

Thanks for all of the replies.  I very much appreciate it.  The inspection panel with the leaking screw is underneath the wing.