Repairing a Zurn Wilkins 975XL Reduced Pressure Principle Assembly 

This is very helpful, but after I have done everything this video suggested, replaced all sealing rubber, the backflow preventer still leak. I do realize that if I open the number 3 valve, the leak stooped. Checked the valve cap sealing area has no problem. I submitted an online question to Zurn custom support web site, and Zurn custom support Terry called me back and did some diagnoses with me on the phone and tell me she can send a new valve cap and a special tool that can unscrew the valve cap (black plastic cap) with no charge. After I have received the package, I replace the valve cap, but it's still leaking, my wife suggested to me that use sealing tape for the valve cap, then screw it down. Finally, the leak stopped. Thanks for this video, Zurn custom support Terry and my wife. Very happy to get this done, saved me lot's of money.

Thanks for the info! Very helpful in assisting me to do my own repair on my 975XL!

Thank you. Very professional and informative. One negative comment: they are bolts, not screws.

**If water is dumping out the vent, it's because you used the 1 pound spring in valve 1! The two springs for valve 1 and valve 2 look identical but they are not! Squeeze the two springs together and you will see the stiffer 5 pound spring is for valve 1 and the weaker 1 pound spring goes to valve 2. If you do not do this, water will dump out the vent. Thanks to Sanjeev Verma down below for his tip on to fix**

VERY HELPFUL - THANKS!

wanted to share my experience with this. i bought a new zurn 975XL valve to replace a leaking valve of the same type. (OMG these things are expensive!!) so i hire a professional plumber to install it, and guess what, the thing is dumping water from the bottom. the plumber tinkered around a bit and told me that the valve id defective and needs to be replaced, charged me a small fortune and walked away. so i was left wondering...do i remove this thing, take it back for a replacement, or tinker with it myself...i am an engineer by education, so kind of touchy about these things too... after sitting over the thought for months (yes, i procrastinate a lot) and watching a lot of videos (including this one), one evening i set about taking the thing apart, piece by piece, cleaning and re-assembling one valve at a time, but no luck...then it hit me...the spring in the first valve was a lot less sturdy than the spring in the second valve...seemed kinda backwards so i interchanged them...and viola!!! no dumping from the bottom valve, not even a drop! so...lesson learnt...trust your instincts (you can do it if you think you can), and try interchanging the springs if you see the same issue!

Thank you for the customer support! I have one of these in my sprinkler system and it was venting a LOT of water when I turned on my system. I watched the Zurn 975 diagnostic video (ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-3d2rNoroZ_c.html) and these repair instructions - with those videos most do-it-yourselfers will be able to repair one of these. This video says "Before servicing the relief valve you want to make sure to check the troubleshooting section of the instructions. The most common cause of discharge from the relief valve is debris in the number one check valve". I couldn't imagine that was my issue, but believe it or not mine had a piece of plastic debris in valve 1 (obviously from something else from my city water system) that was blocking valve 1 and causing a vent just like the video said. I ordered a repair kit and will replace all the parts next time it has an issue, but with this video I got my valve working!

mine seems to leak water out the bottom when pressurized. It does not do this when the short spring is not installed. I think the 4inch rubber diaphragm is louse and needs to be replaced.

Nice, do you have a replacement seat example?

What is the "special tool" to remove and replace the seat?

Mine is dumping from vent and I’ve switched springs and still no effecg

I replaced the rubber seals, o-rings and springs for all three valves and it stopped the leaking. Thanks.

It failed inspection, as the pressure did not change on the second test cock. I cleaned it out. I sanded the inside, as it was rusted. I have droplets leaking out the hole on the cover. Is that ok? Should I paint the inside with epoxy paint to build material back up to original tolerances or can I find a thinker gasket for the plunger?

I don't know if this model is discontinued or has been changed, mine has only two testing caps in the back, So, my question is this device discharges all the water from the bottom when the sprinklers are off, any idea what could be, just changed the inlet and outlet valves because they were cracked, but we just installed universal parts sold at Home Depot, could be this the cause or something inside?

I cleaned value #1 and the relief value but is still leaking water. The rubber seals all seems fine. What could the issue? Should I also open and clean value #2? Pleaes advise.. thank you

I am just replaced the warped diaphram, but now water is just gushing out the bottom. I have inspected everywhere for debris and I can't find any. I thought I was missing a part, but from your video it shows it is all there. I am at a loss.. Any help??

C