Troubleshooting a Sprinkler System Indexing Valve

Here is a question from Neil,
I have a flotec 1 1/2 hp pump which gets water from a large retention pond. The pipe that goes into the pond is mounted on a pvc sled that I made to keep the pipe off the bottom. I have a K Rain 4000 series 5 zone valve (6 outlets, 1 capped) that sometimes skips a zone. In my trouble shooting process, I removed all the screws from the top of the K Rain valve, but have not figured out how the top comes off. Does it twist off clockwise or counter-clockwise? or does it come straight up? Also, once the cover is removed, will this cause my pump to lose it's prime? I dont know if these are related, but In another issue, a few weeks ago, my pump had lost its prime, so I replaced my check valve down by the pond, which seemed to solve that issue. Or so I thought.. My lawn had been getting water for a few weeks since I replaced the check valve, until the other day. At 6:45am I saw the sprinklers were watering on a zone. At 7:00am when the sprinklers should be on the next zone, the pump was running dry. I re-primed the pump which is always a pain... I always end up taking a bath every time I have to prime this pump. I think I'm going to put something togeather that will screw into the pump prime inlet, and have a valve with a hookup for a hose. then whenever I have to prime the pump, all I have to do is connect a hose and open the valve, start the pump, close the valve and disconect the hose. Anyway after priming the pump, it has been working for a few days without losing its prime. Whats up with that? Thanks, Neil

Hi Neil,
The K-Rain indexing valve has a an air vent that you gently tap on clockwise to free the bonnet.
In the photo it is at the bottom left of the valve. Replace both the cam and the diaphragm when rebuilding the irrigation valve. Be sure to install the o-rings! Opening the indexing valve will not lose the prime in your pump.

As to the check valve, I would place it 12" below the ninety coming out of the suction side of the pump. This will save you a lot of time when priming the pump, as you have to displace much less air. If the check valve on your sprinkler pump is failing often, I would look at the screen on the end of the suction line. You do have a screen, not an open pipe, right? It only takes a small amount of debris to jam the plunger in the check valve and leak out the prime.

I hope this helps.