SpudFiles

should I lubricate the metal on metal threads with petroleum jelly to stop them from leaking? Is this a common problem?

use Teflon, pipe thread sealant

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Cras nec placerat erat. Vivamus dapibus egestas nunc, at eleifend neque. Suspendisse potenti. Sed dictum lacus eu nisl pretium vehicula. Ut faucibus hendrerit nisi. Integer ultricies orci eu ultrices malesuada. Fusce id mauris risus. Suspendisse finibus ligula et nisl rutrum efficitur. Vestibulum posuere erat pellentesque ornare venenatis. Integer commodo fermentum tortor in pharetra. Proin scelerisque consectetur posuere. Vestibulum molestie augue ac nibh feugiat scelerisque. Sed aliquet a nunc in mattis.

yer do the Teflon tape or get some loctite thread sealant it comes in a tube like toothpaste but a bit bigger

Chaos

I agree with Chaos, get the liquid thread sealant. Thread tape works, but has a tendacie(sp) to wade up when screwing two pieces together. Wire brushing the threads before doing any of this tends to make a better seal,

I would use both Teflon and pipe dope, that usually never fails.

One or the other.
Theres no advantage to applying both.

I use both cause its pretty much 100% guranteed not to leak.

Pull the teflon tape tight round the threads before screwing them in.

I've got about 6 different pressurised metal-metal screw thread connections on my cannon and none of them are leaking at 160psi.

It did however take several goes to fix all the leaks.

use both- thats what plumbers tell me
when wiping off excess dope it shines the copper/brass real nice.
works first try

Im a plumber and I would tell you to use one or the other.

PTFE or plumbers tape works by melting (due to the friction and compresion created by forcing it into a very tight space) into the microscopic and not so microscopic gaps . The tape that wads up at the ends is whats been forced out cos it wasnt needed.
If you lubricate it it wont work as well.
JMHO

I'm unsure of the exact name, but I use a pink colored teflon tape I found at Lowe's. It's designed specifically for gas applications and is a little thicker, yet more plyable than the white teflon tape. JMTC -Lp

I used some thick nasty looking pipe dope on my first pneumatic and it worked really well.

There are two types of teflon pipe tape: one is intended for use in water lines and such, and the other is intended for use with gas.

The former is usually white and thin, while the latter is usually various colors and three times thicker than the former.

To get those threads to seal, take white teflon pipe tape, and wrap six layers right on the edge of the threads. Once this is done, wrap three layers on the portion of the threads right next to the ones which were just wrapped.

I almost never have pipe leaks when I use this method. If you use too little teflon pipe tape, it will obviously leak, for obvious reasons. Unbeknownst to many, using too much tape will also cause leaks. While excess tape will be pushed out of the threaded joint, too much excess can prevent the two pipes from being twisted together tighter, thus creating a threaded joint with leaks

ive got a thick white one and i only use oneand half layer and test it in the pool for bubbles and i almost always get a perfect seal