Hissing Water Pump

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Giss

Member
Joined
May 31, 2022
Posts
16
Location
Montana
After the first use since winterizing, my water pump cycles on and off. The check valve was acting up also, allowing city water to fill the fresh water tank. I took the pump apart and think I fixed that. But the pump still cycles, and when it shuts off, there is definitely a hissing sound. No water comes out anywhere. I definitely feel like it should not make that sound, but maybe they do right after shutting down...? I can't figure out where else there might be a leak in the system. I ran a ton of antifreeze through the pump and pipes, so I feel confident there isn't a busted pipe anywhere. Is it likely just a pump needing replaced? I've check the input/output hoses and the o-rings look fine..... Rig is only a year old.
 

Giss

Member
Joined
May 31, 2022
Posts
16
Location
Montana
Depending on the pump make/model, you may be able just replace the check valve. An external check valve can even be added if necessary.
I don’t think the check valve is the issue anymore since it isn’t back flowing into the tank. Do you think a bad check valve could still lead to the cycling pump?
 

Kirk

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Joined
Oct 30, 2005
Posts
2,740
Location
Full-time , Escapee
Do you think a bad check valve could still lead to the cycling pump?
It could because the pump shuts off when pressure builds up to the set point. If the pump is leaking back to the tank that pressure will bleed off and the pump will turn on again just long enough to build it back up. I have never heard a water pump hiss, but it might be the pressure leaking back.
 

imnprsd

Well-known member
Joined
Jul 27, 2015
Posts
117
You might have an air-gap that needs to be blead out.

What model pump do you have?

Note: Some pump designs include a drain valve after the pump for this purpose. If your coach does not have one, and if this is an air-gap problem that prevents the pump from priming, and as a result it just spins wildly and pumps no water, then you can add a drain line by inserting a T-Valve and drain hose.
 

Giss

Member
Joined
May 31, 2022
Posts
16
Location
Montana
I don’t think the check valve is the issue anymore since it isn’t back flowing into the tank. Do you think a bad check valve could still lead to the cycling pump?
You might have an air-gap that needs to be blead out.

What model pump do you have?

Note: Some pump designs include a drain valve after the pump for this purpose. If your coach does not have one, and if this is an air-gap problem that prevents the pump from priming, and as a result it just spins wildly and pumps no water, then you can add a drain line by inserting a T-Valve and drain hose.
EE54B11F-54DE-4012-99D1-FC6A1486D7C9.jpeg
It still pumps water, so it’s not a primed issue. No drain valve after the pump from what I can tell.
 

Giss

Member
Joined
May 31, 2022
Posts
16
Location
Montana
It could because the pump shuts off when pressure builds up to the set point. If the pump is leaking back to the tank that pressure will bleed off and the pump will turn on again just long enough to build it back up. I have never heard a water pump hiss, but it might be the pressure leaking back.
Hmmm. Ya know, as I think about that, that just may be the issue. The check valve was already messing up by allowing the city water to fill the tank. Maybe I fixed it enough T to stop that, but it’s still losing some pressure through the check valve…?
 

Giss

Member
Joined
May 31, 2022
Posts
16
Location
Montana
Hmmm. Ya know, as I think about that, that just may be the issue. The check valve was already messing up by allowing the city water to fill the tank. Maybe I fixed it enough T to stop that, but it’s still losing some pressure through the check valve…?
Hmmm. Ya know, as I think about that, that just may be the issue. The check valve was already messing up by allowing the city water to fill the tank. Maybe I fixed it enough T to stop that, but it’s still losing some pressure through the check valve…?
Would I install a check valve before the pump? That way the pressure gets past the valve inside the pump but gets stopped in the intake line?
 

imnprsd

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Joined
Jul 27, 2015
Posts
117
If this hissing is another way of saying your faucet is spitting air... I'm guessing you only experience that on the hot side of the faucet. In which case, maybe you have a leaking pressure relief valve that screws into your hot water heater. (Just a guess.)
 

Giss

Member
Joined
May 31, 2022
Posts
16
Location
Montana
If this hissing is another way of saying your faucet is spitting air... I'm guessing you only experience that on the hot side of the faucet. In which case, maybe you have a leaking pressure relief valve that screws into your hot water heater. (Just a guess.)
The hissing sound is right at the water pump, not at a faucet.
 

imnprsd

Well-known member
Joined
Jul 27, 2015
Posts
117
...Like it's bleeding-off air? ...And it's only present when the pump is operating?
 

NY_Dutch

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Joined
Nov 22, 2010
Posts
7,819
Location
Where our wheels take us!
Would I install a check valve before the pump? That way the pressure gets past the valve inside the pump but gets stopped in the intake line?
An inline check valve can be added on either side of the pump. On the inlet side the arrow points towards the pump, and on the outlet side the arrow points away from the pump.
 

gwinger

Well-known member
Joined
Nov 6, 2018
Posts
226
Location
Natrona Hts PA
The pump you have is only about $100. With all the time you've put into trying to find the problem, just replace it. The rebuild kit is about $40 itself. Sometimes you just have to bite the bullet.
 
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