Dieseling again, is this normal?

[rkr]

I dug out my Hunter Sport after the winter and started shooting it. This is the gun I gave a light tuning last summer, some lubes + fit the guides to the spring. To my surprise it was dieseling badly and went supersonic. After some 20 or so shots it quieted down and I was able to zero the scope properly. Well, today I played a bit with the trigger (somehow the GRT-3 is never just right for me) and went back on shooting. It was dieseling and supersonic again. Is this normal, I thought that once the dieseling is over it won't happen again unless you squirt some oil to the chamber.

[Crock Pot]

Hello,
I replaced a spring and seal in my Gamo 440 recently.  All was well but after about 500 shots with beeman FTS I switched to Crow Magnums (which were much tighter fitting) and the gun began to diesel.  I then switched back to FTS and the problem stopped.  However! I did also find that when I fired in rappid succession i would get minor dieseling too but if i slowed my shooting down it stopped. I am not sure why this happened.  Maybe while your gun was put away over the winter some oil seeped down into the chamber?

[Big_Bill]

Hey Rob,

What lube did you use on your compression seal ? That is probably your problem, you should use a light dielectric grease or light Molly 70 film. Any flammable grease or oil that gets through will cause dieseling or detonation. Your compression seal may be too small, or damaged, allowing excessive seepage !

I hope this helps.

[Big_Bill]

First rkr,

You should never put oil of any kind in a modern springer, ever ! I don't know how you store your rifle, but if standing muzzle up, oil can seep down into your compression chamber, if you oiled your barrel. Oil or flammable lube could be seeping past a damaged compression seal, or a seal that is too small. As below, proper lubes are necessary for the proper function of a springer.

I hope this helps.

[Crock Pot]

Hello Bill,
When I installed the seal I used silicon spray.  I also accidentally shaved off some tiny bits of the seal on the sharp insides of the pressed out slots and holes in the reciever. I thought it would be ok but i think this must be the reason it is dieseling.  I will order another another seal and smooth these edges out properly and put a new seal in.  What is a good brand of grease to use on a seal?
Thanks,
Rob

[rkr]

Big_Bill - 5/29/2008  9:36 AM



First rkr,

You should never put oil of any kind in a modern springer, ever ! I don't know how you store your rifle, but if standing muzzle up, oil can seep down into your compression chamber, if you oiled your barrel. Oil or flammable lube could be seeping past a damaged compression seal, or a seal that is too small. As below, proper lubes are necessary for the proper function of a springer.

I hope this helps.

Hmm, as I have understood it a thin film of silicone spray on the seal is OK when when installing the piston? Other than that there's some moly grease at the skirt of the piston and some tar like grease in the spring. I think this is the usual way to do it?

Gun was stored in horizontal position so it is possible that something has creeped past the seal. The problem is that it allready quit dieseling and continued it the next day. That would probably indicate that the seal got damaged during the first days dieseling. I guess I'll have to tear it down again, it's a good thing I got spare seal and spring.

Cheers, Riku

[Big_Bill]

Hey Rob,

Any dielectric grease that can be found in an auto parts store, or Toyota 70% molly grease, only put a very light film over the sides of the seal.

[Crock Pot]

Great! thanks Bill