M936 Seized Fuel Cap

[rumplecat]

I have my 936A2 on display at the local military museum, I crank it monthly and let it run for an hour or so. We received a C130 for display which came with about 2,000 gallons of JP8 we had to dispose of before we mounted it. So the wrecker has full tanks, so no need to fill for months! I wanted to check the fuel a few weeks ago and the fuel cap is seized tight, so tight that when pressure is applied the fuel filler neck starts to unscrew from the tank! Any suggestions, heat is not an option and I don't want to unscrew the neck from the tank due to it being full and not wanting all the neck sealant falling into the tank!

 

[BKubu]

The threads on the fuel filler neck have most likely rusted and the cap won't come off. Use a chain wrench (a strap wrench with a chain instead of a strap) to loosen it. I have an NOS fuel filler neck if you need it, although you really don't need it. You can just install the fuel cap onto the tank once you have it off.

 

[NDT]

Tap the cap gently with a hammer around the threads.

 

[Valley Rock]

Tap the cap gently with a hammer around the threads.

And if that doesn't work get a bigger hammer !

Applying a moderate amount of heat with a propane torch isn't going to hurt anything and it definitely will help, sounds like you need a couple pair of the big channel locks

 

[charlesmann]

Mine got stuck as well and did as ndt said, heavily persuaded it with a 3lb shop hammer in the loosening direction while using a large strap wrench to hold the neck extension