Rebuilding Minimag (Old Timer)

[greystone]

I think this is what your going thru


http://www.automags.org/forums/showthread.php?t=248105

I tried the suggestion in this thread, the seal was worn. It had a circular mark as described. I flipped it over, re-assembled, still have the same problem.

I checked the tank on 3 other guns to make sure the reg on the tank wasn't dumping some insane pressure....two autocockers and a sterling pump. No issues.

[greystone]

It sounds like you are getting sever overpressure. Did you make sure to put the regulator seat oring in so that the wider end snapped into the holder on the front of the valve back? It won't seal properly if it is on backwards.

Yes. The larger side is snapped into the reg.

[athomas]

When you changed the orings, did you do a complete wipe down of the parts in the valve and reg area with a clean cloth? Perhaps a piece of dirt got caught in the oring on the regulator piston assembly.

[flyingpootang]

It may be a piston o-ring. Degas your marker, remove your velocity screw, remove the spring pack, then the piston, Examine the o-ring around the piston for tears. When installing/inserting new o-rings it's better to lube them to prevent tearing...

[greystone]

Update....

Here's an odd thing. Out of pure frustration I've been swapping around O-rings to see if maybe I accidentally screwed one up while installing. Every O-ring looks fine by visual inspection, no marks or damage. I notice I was getting leak from between the valve and the regulator also, so I put back on my original, 10 year old large regulator O-ring, and the leak from around the reg stopped!

No leaks, I was able to dry-fire the marker until I ran out of air

The trigger pull was extremely hard.

I sit back down at my desk, and notice that the regulator valve spring and pin were sitting on my desk...I didnt re-install them. So apparently I no leak issues when the regulator valve spring and pin is missing...but they are both brand new.

???

[DeuceSV]

How interesting..

[Coralis]

perhaps you have rust or debris in the hole where the regulator pin and spring goes causing some over pressure problems , you could try cleaning it out with Q tip.

[secretweaponevan]

Be sure to thank TK that he designed the reg to withstand 3000 psi.

Interesting that your reg piston didn't overpressure-relieve though. I recommend looking at your reg piston for the malfunction.

[athomas]

That should have definately over-pressured the regulator piston assembly, given that you were putting 850psi directly into the chamber. There is a malfunction inside your regulator piston assembly.