Water Pump Died!

ScottG

The water pump in my 2015 T@B has worked fine for nine seasons. I last used it about three weeks ago. While winterizing a few days ago I flipped on the pump while the system was depressurized, and... nothing. No whirr, girgle, hum, crunch, or sound of any kind. However, there was an obvious current draw on the battery so it was trying to do something. This likely rules out a power supply or pressure switch issue, and suggests a seized motor, but it seems odd it would quit just like that with no warning. (Maybe. There's at least one old discussion here when somebody described a similar abrupt failure.) The pump is currently on my workbench awaiting an autopsy.

So, I'm asking...

• ...has anyone experienced a similar failure with their pump? If so, did you figure out a resolution short of replacing the pump?
• ...if I do end up replacing the pump (which seems likely), any recommendation for a good alternative?

Thanks in advance for any advice or insights.

DukeHewett

Yep, same year T@B and pump failed with no warning within the last year.  Might have been the pressure switch, but it wasn't worth the time trying to troubleshoot further.   We just bought a replacement that was easy to accomplish.  I may have had to mover the new one over or down just a tad, but it fit fine.  Not sure where we got it, but you can Google:  Pentair Shurflo 4008 RV Revolution By-Pass Pump.  It has worked great and supposedly will not burn up if you run it dry.   Under $70 on Amazon.  Good Luck and "let it flow".

jimcenname

I live in a 2019 400, I use the pump and tank water exclusively. I've replaced pumps 3 times until I installed a Shurflo accumulator. Smoother operation and longer lasting service. 

pthomas745

@jimcenname you certainly get some use from your trailer!  Your thread about a faulty Auto Air Bleed valve helped a FB user today.  That strategic whack with a screwdriver handle got them through a cold night!

otr_320

Our '23 320 and two prior RV's came OEM with the Shurflo Pentair 4008. No failures or problems of any kind.

ScottG

@DukeHewett, @jimcenname, and @otr_320, thanks for the input. I'll check out the Shurflo Pentair 4008, and possibly an accumulator.

I guess I can't complain too much. I gotten nine full seasons out of the pump (though certainly not full time), and at least it had the decency to die after my last trip of 2023!  :-)

DukeHewett

Per Pentair/Shurflo regarding an accumulator:

The Shurflo will adjust the outgoing pressure and flow to match the needs of your plumbing system. This means that you do not need an accumulator tank since the Smart sensor pumps will speed-up and slow-down as required to meet the demand for water.

ScottG

I've been looking at the Pentair/Shurflo Revolution Pumps. For 12VDC applications it appears there is a 3GPM/7.5A/55PSI shutoff model 4008-101-E65, and a 2.3GPM/5A/50PSI shutoff model 4028-100-E54.

The smaller version seems like the better choice both for water and power conservation, as well as keeping system pressure within spec. Do others concur?

otr_320

For what it's worth, the 4008 has a small Allen screw that adjusts the shut-off water pressure up and down.

BrianZ

@ScottG what about the control switch unit used to turn the pump on & off?  Is it working normally & does it supply the appropriate amperage for the pump?  On our 2018, I rewired our SeaLevel and Shurflo pump circuits (on the same converter circuit), adding an extra fuse & relay switch, so each could use its own fuse to limit current to the manufacturer's required amperage.

ScottG

@BrianZ, good thought, but yes the control switch is fine. After removing the pump, I checked the cut leads with a voltmeter and was getting the expected voltage when the switch was on (and nothing when it was off).

I've considered it could be a problem with the pump's internal pressure switch, but the current draw--which comparable to when the pump is running--makes me think stuck motor.

ScottG

@otr_320, thanks. I noticed that after I dug a little deeper in to the specs. Good feature.

ScottG

For those interested in such things, I finally dug a little deeper into the cause of my water pump failure. A proper autopsy revealed it was indeed a stuck motor. However, the problem was not the motor itself, but rather two failed bearings on the motor shaft.

The photo below shows the relevant parts of the pump (in my case an Artis Power Drive Series One). Water in the pump chamber is separated from the motor and associated mechanicals by a thick diaphragm. My best guess is that the diaphragm developed a small leak, water seeped into the bearings, and--after sitting for a few weeks--the bearings corroded and froze. Although the motor was trying to turn (hence the voltage drop when it was switch on) the shaft was held tight by the two failed bearings.

Although the diaphragm seems the most likely point of failure for pumps of this design, I'm still impressed I got nine trouble-free seasons out of it.  

vhollow

Thank you, Scott, for the final diagnosis. It is helpful to see how the pump works, and a way in which it may fail.

ScottG

To follow up on this, I really wanted to try the smaller of the two Shurflo Revolution pumps mentioned above, but was surprised to find the smaller 4028 model was quite a bit more expensive than the larger 4008 model. Regardless, I located a "Used-Like New" 4028 for a bargain and took the chance.

I installed it recently and it works great. Really great. Soooo much smoother, quieter, and consistent than the OEM pump. Although I don't completely understand how it works, I attribute at least some of this to the bypass feature of the Shurflo pumps. Now I wish my old pump had crapped out years ago!  :-) 

AnOldUR

Thanks to @ScottG I just made an impulse buy of the smaller 4028 model. My pump is still working but has gotten progressively louder. After a trip last year, the pump switch got bumped on with an empty water tank and unknowingly ran dry for a long time. I've had an accumulator in my Amazon cart, but I'm now hoping that swapping out the pump will help the noise problem.

Also went for a "used - very good" option for almost half price. Fingers crossed.

ScottG

@AnOldUR, I read somewhere in the pump literature that the bypass function is supposed to eliminate the need for an accumulator. One of the big differences I've noticed is that once the lines are primed, the pump shuts off immediately when the tap is closed. My OEM pump would always rattle on for a second or two to reestablish system pressure.

I think newer T@Bs are now coming with these Shurflo Revolution pumps, but I'm not sure when they made the switch.

AnOldUR

@ScottG Well, so far so good. I swapped out the 4008 version of the Shurflo pump for the 4028. Beside the T@B yoga involved, it wasn't too difficult of a job. I can still hear the pump running, but all the rattling is gone. Big improvement!

I'm not getting the immediate shut off that you mention. The pump continues to run for maybe ten seconds to build up pressure. It might have something to do with the by-pass adjustment. Did you make any changes there?

Looking over the parts lists, the only physical differences between the pumps seems to be the Pump Head and the Pressure Switch. The 4008 requires a 10 amp fuse compared to the 4028's 7.5 amp. I'm thinking the only reason is that the additional water pressure of the 4008 puts more load on the motor. I'd be curious to know what the difference is in the Pump Head, but not enough to pull them apart to find out. They look identical from the outside.

ScottG

@AnOldUR, I didn't have to fiddle at all with the adjustments. Is it possible you have an air pocket trapped somewhere? Ten seconds seems a long time--even would my old pump would only chatter on for a second or two after closing the tap (assuming the system was fully primed).

About building up pressure... Another thing I notice about this new pump is that when the lines are fully primed and the switch is off, there is virtually NO pressure when I open a tap. I've assumed this is another feature of the bypass--it only pressurizes the system as needed. This also seems to prevent a big spurt of water when a tap is opened when the pump is ON--another thing my OEM pump tended to do.

AnOldUR

ScottG said:

... Another thing I notice about this new pump is that when the lines are fully primed and the switch is off, there is virtually NO pressure when I open a tap.

Interesting @ScottG. I decided to install an in-line filter that I had left over from a home project. For that I had to drain the lines first. With the pump off I got nearly a gallon of water drained into a bucket in the sink before the pressure was gone.

The odd thing about this project was that my first attempt was to replace the Shurflo in-line strainer with this filter since it has the same straining ability along with finer filtering. The problem was that the pump wouldn't prime itself. I'm guessing that the filter was too restrictive. I moved the pump over to the left enough to make room for the filter to fit on the output side of the pump and it worked.

Not sure how much it will improve the water quality, but it can't hurt.

ScottG

That is interesting. I wonder if somebody tinkered with the settings on your pump (or maybe mine...).

At first I though the lack of tap pressure when the pump was off was odd, but it works just fine. As soon as I open the tap the pump kicks right and I have a steady flow of water.

AnOldUR

ScottG said:

That is interesting. I wonder if somebody tinkered with the settings on your pump (or maybe mine...).

Since we both purchased used pumps it's hard to tell what adjustments were previously done. I just realized that the manual that came with my pump is for the 4008 model, not the 4028. The pressure shut-off for the 4028 is 50psi compared the the 55psi of the 4008, but I'm not sure if the by-pass instructions are any different. I'm looking for an easy way to check the pressure in the line after the pump cycles off.

It sounds like your by-pass is set to open much earlier than mine. I'd be interested to hear from others about how theirs works? How much water will come from the faucet after the pump switch is turned off?

ScottG

FWIW, mine came with the same manual. That said, I think it had a little table that had the specs for the four different models. I suspect the adjustments are the same for all.

ScottG

@AnOldUR, I wanted to follow up on this discussion having now field tested the new pump.

In actual use my pump is behaving similarly to what you described above. When first priming the lines, it will run for some time (ten seconds seems about right) to build pressure. Once most of the air is purged it behaves much like my old pump--running for a couple seconds to reestablish pressure after closing the tap. Once pressurized, I also get sustained flow from the tap for several seconds with the pump off.

In hindsight, when I first installed the pump I tested it with the Alde bypassed. This greatly reduced the volume of water in the system, and--probably more importantly--eliminated the "air cushion" inherent in the Alde's HW tank. I suspect this air cushion acts as an accumulator of sorts, increasing the time it takes for the system to build pressure once the tap is closed, and providing a certain amount of sustained pressure when the pump is off.

In summary, I think both our pumps are working properly. I still really like the Shurflow as it is much quieter and smoother than my OEM pump ever was.

AnOldUR

ScottG said:

In summary, I think both our pumps are working properly. I still really like the Shurflow as it it is much quieter and smoother than my OEM pump ever was.

I agree. I really like how much quieter and smoother this pump is. I'd hoped to attach a pressure gauge to the system (maybe at the outdoor shower since I have a quick disconnect there) to get a measurement of the actual pressure the pump produces. My thought was that if there was too much pressure it might contribute to how much water flows after the pump is off. We're getting ready to leave for uCamp, so pressure testing probably won't happen before then. We're in the boondock section, so the pump will get a weeks worth of testing there. Actually we're heading west from uCamp for almost three months before heading home, so have fingers crossed that swapping pumps was a good decision.