MTFCA Forum

I replaced my sediment Bowl and I reused the old petcock after clearing the blockage on the top of it and the petcock is leaking not from the threads but the actual valve part, the spinning part. how might I be able to fix this? I did though disassemble the petcock valve to clean and uninstall and reinstall it but there was no gasket or anything.

Might I add that it also only leaks when the sediment bowl valve is open when I shut the fuel off it quits leaking mind you there's still fuel because if I open the sediment drain valve fuel comes out of the bottom. So it seems it only leaks under a light pressure.

A common problem. You could try lapping the valve with a fine abrasive (rubbing compound, etc. - google it) - it didn't work for me so I bought a new petcock. An alternative is to remove the valve and replace it with a brass pipe plug. Not original but it does the job. Normal procedure calls for turning the fuel valve off before draining the sediment bulb. With a plug you can turn the fuel off and remove the plug to drain the bowl - more efficient anyway.

Lap the shut-off valve as previously mentioned and then lubricate it with bar soap.

Ivory bar soap.

Do not be aggressive with lapping or you’ll screw the pooch & create a bigger leak on & off.

Use tooth paste. I found you can go to far with 400 grit lapping compound.

There is an aircraft product called “EZ Turn” that is fuel resistant, meant to lubricate the turning parts of fuel line valves and petcocks. It will stop minor leaks and seepage.

I also use EZTurn BUT be careful to use it sparingly - it will block the orifice !

RajoRacer wrote: ↑

Sun Feb 16, 2025 4:14 pm

I also use EZTurn BUT be careful to use it sparingly - it will block the orifice !

Well said Steve !! “A little dab ‘ll do ya !”
Apply a thin film to the “cone” make sure none gets in the orifice of the valve. It keeps the moving part from seizing, and will stop a minor leak. Three years now, mine turn easily and don’t seep.

Hi Lucas,
I use timesaver to lap the valve & for lubricant I picked up a can of G-363 military grade plug valve grease. I believe EZ-Turn is the same spec.
Craig.

I've lapped several similar fuel valves with timesaver then used EZ turn. They don't leak and turn well. Unfortunately, it only comes in a large 5 oz tube that will take me 5 lifetimes to use. I plan on getting some small bottles (prescription bottles?) and give it to friends on tour.

I've done the same Noel - more in a tube than I'll ever use !

I picked up this @ a swap meet it's about 1/3 full I will never use it all up but don't know anyone that repairs valves other than me. Craig.