[nippaero]

Been reading up on sealants for use on the AN fittings of my motor/oil lines and fuel lines.

Which one of these is should I be using?

Permatex Aviation Form a Gasket
Permatex #1
Permatex #2

 

[BillL]

If you are talking about the NPT ends, then:

Aviation Form a gasket is #3

So, I am using #3 and have for many years on engine joints. #2 is not much different. I would not use #1.

Nothing for the 37 Deg flares and nuts.

They can be dissolved with alcohol, but nothing petroleum derivatives, like oil, gasoline, or mineral spirits etc.

 

[Pat Stewart]

Ok, here goes, don't use anything on fuel lines and not sure if you really need anything on other AN fittings.

 

[Mark Dickens]

Connections using a flared end do not get sealant. They are to be installed dry. Connections with NPT threads MUST have a sealant to be properly installed.

Sometimes you'll have a fitting that has one end flared and the other end NPT. An AN816 nipple is a good example. One end is manufactured to accept a flared connection and the other is a NPT. Only use sealant on the NPT end.

 

[nippaero]

Ok. I am going to use the #2. Do I use it on the fuel system as well?

 

[Walt]

ALL pipe threads will leak if not sealed, so you decide
I use one of the following depending on application: Tightseal light, Loctite 567, Permatex #2

 

[Pat Stewart]

Agree wth Walt on pipe threads only.

 

[nippaero]

How about the straight threads on the fuel pump fittings. Is the rubber O-ring enough by itself?

 

[BillL]

How about the straight threads on the fuel pump fittings. Is the rubber O-ring enough by itself?

Yes, a light lube to allow the ring to seat, but that is all.