My Shurflo pump keeps cycling after repairs

[grsterr]

Hello, All. I rarely post here, but I have learned an amazing amount reading the daily posts and your kind and well-informed responses. I am currently stymied and am seeking some advice. In the recent and rare multi-day freeze here in Seattle, my water system was compromised. I don't winterize the water system as it rarely freezes here and I use the van year-round. An electric air dryer usually keeps the van a little warmer than outside . . . But, I accidentally had left the pressure switch on during the sustained freeze. The result was a burnt out pump motor and leaks in the galley faucet connections under the sink and in the water valve on the back of the toilet. I have installed a new Shurflo pump, replaced the galley faucet assembly and made new connections to the supply lines, and replaced the water module assembly on the Thetford toilet. But I still have a small pressure leak somewhere, indicated by the pump cycling very briefly every 15 seconds or so. The PEX lines and fittings all seem to have weathered the freeze just fine. I can find no sign of water leakage anywhere I can see. Can you suggest where else the system might be losing pressure if no water is leaking? Thanks for any advice you can offer. --Glen (2000 Dodge Ram 3500 Sportsmobile, which I use often and maintain well). PS: The lines and fittings to the shower handles (hot and cold) show no signs of damage or water leakage. And, although I can't easily get to them, the supply line fittings to the Atwood water heater (propane) do not show signs of leakage that I can see.

[1der]

The water system in our rigs is the one system that can keep me up at night. A cycling pump is a leak or, less likely, an improperly adjusted pressure switch. And the leak could be multiple leaks. If the pump is cycling, it is highly likely water is dripping somewhere, inside the van, silently, with only the intermittent cycling pump indicating a leak - somewhere.

I would make sure there is no air in the lines and that the water heater is completely full. Turn on each faucet until the water flows with no sputtering. That eliminates any air being compressed in the lines. Water does not compress.

I have placed paper towels under/around various fittings to determine if a slow leak is present, sometimes it takes 24hrs to find what paper towel is damp. Lift the floor covering if possible, feel the walls to look for signs of dampness.

I have had hairline cracks in the threads of the filter attached to the pump create this type of problem. I would certainly check that, and certainly change that if not already done. I caught that with a paper towel, super slow leak.

Did the water heater freeze? I would turn off the cold water supply valve to the water heater to see if that makes a difference in cycling. You are going to have to isolate individual runs as much as possible. Basically, if the pump is still cycling, then the leak is in the lines still under pressure. Be methodical in reconnecting lines, one at a time, testing for cycling after connecting.

Try disconnecting the faucet lines and cap the ends. See if the cycling still occurs. If yes, then probably not the faucet.

When I install my water systems I incorporate multiple valves to be able to turn off various runs. This can help with isolating leaks or shutting off an area that might be damaged, or shutting off water to an outdoor shower during the winter. A little extra work and a few more dollars but worth it to me. if you are handy with a PEX cutter and ring crimper, a set of PEX ball valves is very reasonable - $30 for ten valves.

Let us know what you find!

[REF]

Yup…..if there’s a leak, most likely it’s at a fitting. Do you have an exterior threaded city water fill? That was the culprit of a tiny leak that was cycling my pump, hairline crack in the plastic on the backside after a freeze. Replacements are available

[moorefc]

Cap the new pump. Does it cycle?

If not, you have a leak, so follow the lines and check the connections....If you can isolate any part, that can help.

[arctictraveller]

My pump froze last year and broke the swash plate so I canabilized a different pump for parts. Since then, the pump cycles about every minute for a second or so, but there are no external leaks. I suspect it’s leaking internally, but I simply shut it off if I’m not using it. Still, if your pump is new, that’s not likely.

[grsterr]

Thank you for these great suggestions, Ray! I so appreciate your thoughtful and multi-faceted reply. I will keep checking my system's components. I'll post what I discover -- and hopefully fix -- once I have traced the problem. --Glen

[grsterr]

Originally Posted by REF

Yup…..if there’s a leak, most likely it’s at a fitting. Do you have an exterior threaded city water fill? That was the culprit of a tiny leak that was cycling my pump, hairline crack in the plastic on the backside after a freeze. Replacements are available

Thank you, REF. I will check the city water fixture. I have replaced it once a few years ago due to a leak that I could actually see. I'll check for a hairline crack. If the rest of the system tests out to NOT be leaking, I can always replace this fixture as a final resort.
--Glen

[grsterr]

Thanks, Moorefc, for the suggestion of isolating the pump to check if there is a pressure leak prior to the outgoing water pipe. I believe this would tell me whether there is leakage in the tank, the fill shut-off valve, and the strainer connections. If not, I'll know to look further downstream. --Glen

[grsterr]

Thanks, ArcticTraveller. I know the pump is brand new and works fine. But, until I trace and fix my pressure leak, I will simply shut off the system when not needed. Fortunately, my water switch is conveniently located above my galley counter and is easily reached.
--Glen

[mikracer]

The check valve in the base of the pump can be faulty too. I didn't have any leaks but had the pump cycle every so often. After replacing it, the system holds pressure.

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