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]

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.

https://www.amazon.com/gp/aw/d/B00SQ4F4V2?psc=1&ref=ppx_pop_mob_b_asin_title

 

[grsterr]

Thank you, mikracer. The pump is brand new, so I am hoping the pressure leak won't be in there, but I will keep this possibility in mind if nothing else solves my problem. --Glen​

 

[mikracer]

Thank you, mikracer. The pump is brand new, so I am hoping the pressure leak won't be in there, but I will keep this possibility in mind if nothing else solves my problem. --Glen​

You can pull that part of the pump off and check the plunger to make sure its not stuck. Easy to do and doesn't cost anything. If you aren't seeing any water leaking anywhere, this is probably the culprit.

 

[boywonder]

My shurflo started randomly cycling a few years ago...

I pulled it apart and found bits of plastic swarf in the pump from when the holes were drilled in the plastic fresh water tank. The plastic shavings were in the bottom of the tank and at some point got sucked into the pump.

Plucked out the bits and the pump has worked fine since.

 

[Steve Hunt]

My shurflo started randomly cycling a few years ago...

I pulled it apart and found bits of plastic swarf in the pump from when the holes were drilled in the plastic fresh water tank. The plastic shavings were in the bottom of the tank and at some point got sucked into the pump.

Plucked out the bits and the pump has worked fine since.

I went to great lengths to get all those bugger plastic swarf bits out of my tank too. So far it appears none made it to the pump but even with compressed air and latter water flush it was tough getting them all.

 

[Orv-SMB]

Make sure you check outside the van. The city water feed line on mine runs under the floor and is a pretty good candidate for freezing. Also, I once had the check valve stick on the city water fitting and water slowly leaked out of the cap, causing the pump to cycle; it was hard to see because it was evaporating almost as soon as it hit the ground.

 

[Scalf77]

The fill valve is also a know weak spot for cold temperatures.

While this shouldn't be the OP's issue, as he replaced the water pump. I too became a victim of that cold spell. My original plan was to keep the heater on, I have a Truma Combi that takes propane and electric. I usually just keep on electric low and heat the van if it get cold at night.

That plan fell apart when the wind knocked out power. I could have fired it on propane, but decided to take the easy way out. I opened up the hat water tank, but could not open the tank drain as it was outside and already frozen. I was able to run water out of the faucet and shower and thought I did enough, power was out and my large air compressor was empty, so I couldn't blow anything out. I must have got a little water left in the pump, so after the freeze it just ran, but no water came out.

I took it a part and found this valve was stuck.

I took that apart and was able to free it up.

I put it back together and it works fine.