AusVarmint

Hi all,
I finally got a new piston seal for my Diana model 36 and about to reassemble.
Shot lots of air rifles over the years, but this is the first time working on one.
The new Seal is synthetic and impregnated with moly, supposed to be permenantly lubricated. This replaces a leather seal which I used to oil, so does the new type not require oiling?
Need some advice on greasing for reassembly also. Am I correct in keeping compression chamber and seal dry and just lubing (moly grease) piston from rear of seal and lightly greasing spring.
Any advice appreciated

What sort of moly do you have?

There is common moly grease which has a small amount of moly in it, around 3% and is a lightweight grease, and there is moly paste that feels more "gritty" and stiff and has around 70% moly.

Common moly grease will tend to move around and shift with the firing cycle as it's soft and not all that sticky. Moly paste acts to impregnate the metal surfaces.

Before putting the piston back in, it is a good idea to smooth and deburr the cocking slot - this removes sharp edges on the inside that can cut the piston seal on reassembly. And it can smooth cocking.

Before reassembling, clean out the compression tube with a lint free rag on a dowel or some paper towel to remove any old lube and crud.

You can use the likes of metho to help clean the stuff out but be sure it's fully wiped out and dried before reassembling.

Piston - you can give the piston skirt a bit of a smooth and polish while it's out, this can make cocking smoother and reduce abrasion inside the cylinder. This is a friction point that also needs a light wipe or brush of lube around the circumference. That is one place that moly paste goes.

You can put a light wipe of moly around the circumference of the piston seal, just a very light wipe as too much will act like a sticky brake and slow the piston down. Some folks wipe it on behind the seal. TBH I actually prefer a dry Teflon wax lube on the seal and have gotten better velocities with my two springers over moly paste on the seal. Just a dry wax Teflon bike chain lube. Wipe it on the circumference of the seal, let it dry and reassemble.

Cocking linkages and breech jaws and breech pivot bolt will all benefit from a light wipe of moly.

Moly on the rear spring guide.

Spring - a light coat of "spring tar" which is a heavy shockproof grease is what's normally used, however you can put a light coat of moly on it.

Thanks,
Moly is the 70% stuff I got from the fellas I got the seal from.

Ok, good to go then.