De-winterizing 5th Wheel- Water Pump Issue

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Metalman RVer

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I decided to de-winterize our new to us 5th wheel Glendale Titanium today, this being the first time for getting things going for me since owning this unit & the 12v water pump wants to keep running on after building pressure. I dont think it has freeze damage as I dissconnected the lines running to it (inlet & outlet) after putting air through the system last fall. Purged the air from the HWT tank today by opening the pressure relief valve till water came out there.  Purged air from all taps, shower, outdoor shower, toilet etc so dont believe that there is air pockets in the system.  The pump is slow to kick in & then when it does it builds good pressure & then after pressure builds it does not shut down completly, just humms quietly but will not cycle off.

No visible leaks anywhere in the system.

Any ideas?

I did buy a spare pump, just to have, so can switch it out if need be.
 
What year is your RV?
How do you fill the water tank?  Is it by opening a tank fill valve. If it is, that valve may be partially open or leaking by allowing the water to go right back to the tank and not allowing the pump to shut off.
 
I have had that happen when I didn't get the cap on the valve where I attach my anti-freeze syphon really tight.  I mean with a pair of vice grips.  I hope this makes sense. 
 
Rene T said:
What year is your RV?
How do you fill the water tank?  Is it by opening a tank fill valve. If it is, that valve may be partially open or leaking by allowing the water to go right back to the tank and not allowing the pump to shut off.
Click to expand...

It is just by putting the hose in the removable fill cap (gravity feed).

It is almost like the cut in/out sensor is not working properly, lets the pressure drop to a dribble before cutting in, then once up and running, it is fine, only it never completly cuts out once pressure builds, just sort of hums very quietly & vibrates a little bit when not needing water, never shutting off completly.

HWT is working ok & no air in the system, so no lack of bleeding out the air.

Maybe time to change the pump out?

 
stevensc said:
I have had that happen when I didn't get the cap on the valve where I attach my anti-freeze syphon really tight.  I mean with a pair of vice grips.  I hope this makes sense.
Click to expand...

The antifreeze syphon is on the suction side of the pump. The issue this poster is having has to do with the discharge side of the pump. If that cap is not tight, the most you'd be doing is sucking air I think.  It would hurt to check it though. Their pump is not building up enough pressure for the pump to shut off.
 
metalman55 said:
Titanium is a model year 2007.
Click to expand...

Being 11 years old, It could also be the check valve inside your pump could be letting water back into the tank. I would think that would be the last thing I would look at.
 
I wonder if the check valve is just a floating ball & if it can be taken apart & inspected?

I can have a look tomorrow.........

 
metalman55 said:
I wonder if the check valve is just a floating ball & if it can be taken apart & inspected?

I can have a look tomorrow.........
Click to expand...

Can you reply to my 1st post?
 
Rene T said:
Can you reply to my 1st post?
Click to expand...

I am not exactly sure of your question, but there is not tank fill valve, just a fill hose leading to the tank that fills by gravity.
 
metalman55 said:
I am not exactly sure of your question, but there is not tank fill valve, just a fill hose leading to the tank that fills by gravity.
Click to expand...

OK. That eliminates one possibility. Thanks.
 
Well, being a newbie I gotta be missing something here..............changed the pump out for the new one I had purchased for standby & it does exactly the same thing............will start up when there is demand (works fine), then once there is no more demand, it builds pressure but does not shut down completly, just keeps running on quietly once the demand is off, but just like the other pump, just sort of hums, so that you can hardly hear it, but can feel it when you put your hand on it & does not shut down until killing power to the pump in the coach.

No visible leaks anywhere.

The logic mentioned about somehow there being some water returning to the fresh water tank seems like a possiblilty, but I have no idea how.

I wonder if the water is somehow getting to the grey or black tanks?  Since all is clean I suppose I can pull both drain valves & see if it drips when the pump runs on.



 
The only way water could be getting to the gray tank is by a leaking sink faucet. And the black tank, the toilet would need to be leaking. You'd see the water leaking in any case.
How long would the pumps do this? If you let them run would it go on forever?
If you don't see any water anywhere, it sounds like it may be going back to the tank and it would be through a tank fill valve. I know this RV is new to you, but are you sure there isn't a tank fill valve? My RV has one and also the gravity fill pipe you mentioned you have.
Did you buy this RV through a dealer or private sale. Either way, can you contact them and ask if there is a tank fill valve someplace.

This video gives you a good understanding on the water system:

https://www.youtube.com/watch?v=LkU0FyFYr-k
 
I dont think it has a fill valve.  If these attachments came through ok, one shows the new pump in place & the other is where the fresh water tank is filled by gravity on the left & the other hookup is the spot where you connect to city water, likely pretty standard.

BTW, after going back out after lunch & working on it some more, after running it for an extended period of time, the pump did eventually shut off finally.  I am thinking that it has a bit of air in the pump & that is the cause for the pump to keep running on.  I am planning to go out & top up the fresh water tank again & run some more water through the system & see if it continures to improve. I am learning!!  Thanks for the comments.........much appreciated!
 

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Try for the 2nd picture showing the pump mounted up.
 

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Rene T said:
How long did it run before it shut off. Mine runs about 15/20 seconds before it shuts off.
Click to expand...

It ran on indefinetly until it got all the air out. After several minutes I would shut it down, not wanting to overheat the pump motor.  I did this several times before suspecting there was a deeper problem that I was missing, then reaching out here.

It just took an extrordinarily long time to get the air out I now believe. There must have been a bit of cavitation in the pump I am thinking, keeping it from building proper pressure.

Now it runs like yours 10-15 seconds before building pressure & shutting off. 

 
Update..........water pump is working flawlessly now.  Must have just taken a super loooong time to get air out of the system. :)
 
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