Fuel leak? From sump or somewhere else?

[Supercop0184]

What say y'all? 

[N201MKTurbo]

Put a new O-ring on it.

Get a friend with a rubber glove (those are hard to find some times)

Have him unscrew the valve and put his finger on the hole.

Clean and get a new O-ring, then hand it back to him and have him screw it in.

Better he gets his arm soaked with gas instead of you.

Edited May 17, 2016 by N201MKTurbo

[Marcopolo]

I say o-ring on the sump, Might try to tighten it just a scoche!

[Mooneymite]

Is it an active leak, or did it just not seal properly once?  It doesn't look damp from the picture.  A fuel stain can last a long time.

[Guest]

Try cleaning the stain with some Acetone or nail polish remover. Then see if it comes back.  The O ring is an MS29513-014, or if replacing the drain it comes with a new one.  Be very careful removing the drain when the tanks are full, being soaked in 100LL and catching fire would be fatal.

Clarence

[Yetti]

I would buy two.  Keep one in the plane, will come in handy when the other one goes

[N201MKTurbo]

Sometimes some crud gets in your tank and a little piece of something will get on the valve seat and keep it from sealing. A few pokes with the fuel sampler will often clear it out and all is well again.

[neilpilot]

Just now, N201MKTurbo said:

Sometimes some crud gets in your tank and a little piece of something will get on the valve seat and keep it from sealing. A few pokes with the fuel sampler will often clear it out and all is well again.

Correct, but clearly not the OP's issue or the stain/drip would be to the floor.  

Suggest you fly the tank nearly empty, and order a complete drain valve as well as a new o-ring.  Install the new valve and keep the used valve, with new o-ring installed, with your spares in the luggage compartment.  Useful to have on the road if a persistent drip suddenly occurs.

[N201MKTurbo]

11 minutes ago, neilpilot said:

Correct, but clearly not the OP's issue or the stain/drip would be to the floor.  

Suggest you fly the tank nearly empty, and order a complete drain valve as well as a new o-ring.  Install the new valve and keep the used valve, with new o-ring installed, with your spares in the luggage compartment.  Useful to have on the road if a persistent drip suddenly occurs.

I have had them leak and the fuel wicks along the surface of the wing. I would expect stains on the end of the valve though.

[Supercop0184]

Anyone know the part number for this valve by chance? And I believe the o ring comes with the valve?

thanks all for the help 

[Guest]

8 minutes ago, Supercop0184 said:

Anyone know the part number for this valve by chance? And I believe the o ring comes with the valve?

thanks all for the help 

Normally an F391-53S.

Clarence

[carusoam]

1) Buy the new valve.

2) swap out the old valve.

3) clean the fine dirt particle out of it.

4) store the cleaned old one on the hat shelf.

5) check the dirt particle to see if it is rust.

6) if it is rust, check the fuel neck at the top of the tank to see if it is SS.

7) if it isn't stainless steel, get one or two from your MSC or LASAR.....

8) take the advice on safety working with100LL drain. It is easy to light on fire and difficult to put out.

Some PP ideas rolling around in my head based on my 1965 M20C experience...

Best regards,

-a-

[DXB]

 

On 5/17/2016 at 6:47 PM, M20Doc said:

Try cleaning the stain with some Acetone or nail polish remover. Then see if it comes back.  The O ring is an MS29513-014, or if replacing the drain it comes with a new one.  Be very careful removing the drain when the tanks are full, being soaked in 100LL and catching fire would be fatal.

Clarence

Now I have the same problem- very slow intermittent leak at the right sump, leaving a similar stain as the OP here on my '68C.

Are the parts the same if one has bladders, or do they have different drains after bladder install ?

I will first run that tank down to <5gal remaining, maybe siphon as much of the rest out as possible, and get experienced A&P help to avoid untimely demise by self-immolation.

[Guest]

3 hours ago, DXB said:

 

Now I have the same problem- very slow intermittent leak at the right sump, leaving a similar stain as the OP here on my '68C.

Are the parts the same if one has bladders, or do they have different drains after bladder install ?

I will first run that tank down to <5gal remaining, maybe siphon as much of the rest out as possible, and get experienced A&P help to avoid untimely demise by self-immolation.

I’m not sure what drain valve is used in the O and N bladder installation.

Clarence

[jaylw314]

On ‎5‎/‎18‎/‎2016 at 6:13 AM, N201MKTurbo said:

I have had them leak and the fuel wicks along the surface of the wing. I would expect stains on the end of the valve though.

+1, just because the stain is on the wing does not mean it isn't a leaking valve.  If the leak is slow enough the fuel will wick up and and then evaporate before there is enough to drip on the floor.

Edit:  well, that's great, I just +1'd a 2 year old comment!   Never mind me....

Edited April 5, 2018 by jaylw314

[DXB]

So the part for the bladders per the new STC owner Griggs Aviation is F391-18. It doesn't look like this one comes with an O-ring though.  Anyone know if it needs one??

[LucasC]

I have the same leak but changing the gasket has not helped. Cant tell if its coming from the rivets next to it from the  nut plate or something else.