SpudFiles

I have a rainbird CP 100 Sprinkler valve and whenever I fill it it leaks out of the top where I drilled to put the blowgun in. It doesn't dump the pilot, but it loses pressure quickly. I am still able to shoot it if I use a compressor and shoot it right away before it loses all the pressure. I have tried jb-weld and epoxy on the blowgun to keep it from leaking but it still leaks. Any idea what could be wrong?

my guess would be that when you screwed in the blowgun or hose barb that the hole you drilled was too large and you didn't get a good seal. if you want to fix it you could get an adapter for the blowgun that makes the male connector larger by a little bit and the drill a slightly larger hole in the valve and screw in the blowgun with the adapter.

A photo would help a better assessment of the problem

There is a product called Leak Lock which works wonders. I use it on air conditioning systems. It's blue and available in a tube or jar at any fine hardware store near you.

teflon tape=solve all

Is it leaking through the fitting or around it? Spray it with some soapy water to find out (look for the bubblies).

If it is leaking from around the fitting, just put a good epoxy around it. It will seal it, but make it non removable. If it is leaking through the fitting, then replace it.

Another thing to check is the drain plug. It should be a tiny screw found somewhere on top of the valve. You'd be surprised at the number of people who forget about this little doohicky. Just take out the screw and fill in the hole. Oh, and make sure you have filled the solenoid hole correctly.