Mooney M20E leaking fuel drain valve

[Stefano]

Hello Friends 

I have a problem with a leaky fuel drain valve

it is the old original type, that is riveted to the lower wing tank panel

On the other fuel tank the drain valve has already been replaced with a more modern threaded valve. This was done before I had the aircraft and I don’t know if it was performed according a Mooney instruction or bulletin

Can anyone give me a suggestion?

Attached photos of the leaky drain valve and the newer type of valve installed on the other tank

Thank you very much!

stefano

 

[N201MKTurbo]

I think your best bet is to replace the the old valve with the new style. I see the rivet is leaking on your new valve. To fix it you need to drill out the rivets and put new rivets in. When the rivets are put in, they should be coated with sealant before they are set. Either way yo need to remove an access panel to get access. Cleaning the access panel is way more work than the valve change.

[Shadrach]

Mine were done in the 90s.  The new drain looks properly located and installed though we can only see the outside.  It is clearly leaking, but that may simply be the o-ring on the drain that seals it against the mounting plate but as Rich mentions above is more likely coming through the rivet. You will need to have SB M20 188A completed on the tank with the old style flush drain.  As an aside, there is no need to slop sealant on the old patch the way it was done on your plane.  The patch is visible on mine but the rivets are clean. The patch is sealed from the inside. Sealant has very little effect when applied externally. We filled the external void under the patch with clear RTV. 

[47U]

9 hours ago, Stefano said:

Can anyone give me a suggestion?

Sometimes, a couple bursts of shop air up through the sump drain clears debris that is stuck to the o-ring.  If you have tank sealant and/or top coat degradation generating debris, the shop air trick is going to be short term.