SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

You can always do a "guts swap" on a valve, where only the original valve body remains. R204 diaphragms are definite candidates for replacement.

This should do it.
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I need to make a youtube video of how to repair this particular valve. This is the only style valve I ever have to do this on.
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Just unscrew the bonnet and take it off. Don't forget to turn the water off first.
Let all the water drain out. A pro doesn't have to let all the water drain but you better because it's easy to put this bonnet back on crooked or turned a little bit.
Make sure no debris gets inside the valve during this process. If it does flush it out.

Ok here's the part I've come to find is the best way of replacing the diaphragm and bonnet.
You want to do it all at once.

Attach the diaphragm and spring to the bonnet first then place the whole thing onto the valve body.
What you do is turn the screws through the diaphragm about three threads worth. Then pull the screws up so the diaphragm is tight against the bonnet.
You'll have to hold the diaphragm tight against the bonnet because the spring will be pushing it outwards.
Now you place the whole thing onto the valve body. Wiggle it back and forth until the bonnet is flush. Now tighten the screws while holding the bonnet in place.
Pay close attention to the screw holes and the small plastic nipple so the bonnet is on straight. You don't want to damage that nipple.
It's very easy to miss the holes and damage that nipple when you tighten the bonnet. That's why I do it this way.

You can try just placing the bonnet on the body first then the spring then the bonnet if you wish. That's how I used to do it until I learned but pay very close attention to that plastic nipple and screw holes. It's easy to mess up this way.

After you're done open the bleeder screw before turning the water back on. Turn the water on slowly. Then go back and turn the bleeder screw off. You do this to get the air out of the valve. A valve can stick on with air in there. Also adjust the flow control. You don't want it open all the way.

Let us know how it goes. Good luck!

If you buy the entire valve, you can use it as a guide to how everything goes together. First-timers do well to have the entire new valve in hand.