Community Forums

Jim & Ingrid McIntosh · 01-30-2010, 12:08 PM

Hello everyone...guess I was too optimistic yesterday...pump #6 (5.7 ext series) failed this a.m. after being installed for approximately 18 hours. We will return to CW Savannah on Monday. I agree w/you Basil that the R/O system can't be the culprit but no one wants to listen at Shurflo or CW. We fulltime also and use the R/O constantly, dishwasher and W/D daily as well. We managed to go through just 2 5.7 pumps in 5 years, but have now blown through 6 in less than 2 months. Nothing new on our coach - just Shurflo's redesigned pump. Any more thoughts out there?

DriVer · 01-30-2010, 12:19 PM

Thanks for the information on that "center" screw adjustment. I'm going to have to go and check mine out. I cycled through a few 5.7s myself but overall it's much better than the OE pump.

EngineerMike · 01-30-2010, 12:31 PM

Jim- The RO system per say cannot be the problem; you use city pressure to run the RO membrane, which then dumps into the tank at zero pressure. No way the pump can be affected by the zero pressure disconnect @ RO input to tank.

However, there might be a cross connect between the City input and the pressurized 5.7 output. If the 5.7 is cycling due to this, and if you have pressure gauges, you should be able to see the leak-down on at least the post-canister-filter gauge which (on my 06 anyway) read some feedback of house pressure. I doubt this is the issue, as the cycling would be minimal.

For my edification, what is a 30psi accumulator? The 5.7 makes (or should) about 65psi high end, and should cycle in the neighborhood of 40-45 psi (that's a guess as I don't recall a specified trigger pressure).

Usually an accumulator is a dumb device consisting simply of a volume tank to "accumulate" pressure; the tank adds volume to the system, and a higher volume at a given pressure is more resistant to sudden pressure drop. E.g. if you had a 100,000 gallon pressure tank at 65psi, and you took a 5 gallon shower, you would still have 65psi in the 99,995 gallon tank at any rounding error you could see on a gauge. Smaller accumulator tanks (in the 2-5 gallon range) will cycle more obviously on a gauge.

BTW, I'm not advocating the 100,000 gal accumulator; although it would be nice for long showers, your fuel mileage would probably suffer.

DGShaffer · 01-30-2010, 12:57 PM

I just installed a 5.7 figuring they must have ironed out the kinks by now! I haven't put water back into the system to test it out but you can be shure that when I do I'll have a screw driver in my hand.

Great advise on the adjustment. I do hope I have better luck with mine then what I've just read.

Jim & Ingrid McIntosh · 01-31-2010, 07:55 AM

EM, You are correct about the 30psi. This accumulator tank has a pre-set at 30psi. The thought was for the accumulator to eliminate the initial start-up stress on the pump and the pulsating since the adj screw did not correct the pulsating. It worked as far as the pulsating stopped but the pump still stopped working.

happycamper1 · 02-02-2010, 11:34 PM

Just purchased a 05 Alpine coach 36, on the second trip out I was inside the outside storage compartment and hear a low humming noise. I looked around and found it was coming from the 5.7 Shurflow water pump. No water was on but the pump was running (pump was very hot so I had been doing this for some time) but not pushing any water. What gives. Anyone have this problem and have an answer. On an old motorhome, a pump I had did the same thing and it was a bad pressure switch. I understand that the 5.7 doesn't have one so I am at a loss. I did hit it and it stopped and did not run until someone turned on the water inside and after they turned it off, it started running again.

Wayne R · 02-03-2010, 06:04 AM

Happycamper1,
Do you have the water valve in the sanitary station on fill tank? If so the pump will run slow all the time as you describe. Circulating water to and from the tank.

Basil Shannon · 02-03-2010, 07:16 AM

Quote:

Originally Posted by happycamper1

No water was on but the pump was running (pump was very hot so I had been doing this for some time) but not pushing any water. What gives. Anyone have this problem and have an answer. .

This failure mode has happend to me several times. Bad pump. Go buy a new one. The existing one is guaranteed for 3 years from the mfg date on the nameplate. If still in warranty, send it in for repair/replacement and carry it as a spare. You will glad you have it next time the pump fails. IT PROBABLY WILL.

Ken T. · 02-03-2010, 10:39 AM

Quote:

Originally Posted by happycamper1

Just purchased a 05 Alpine coach 36, on the second trip out I was inside the outside storage compartment and hear a low humming noise. I looked around and found it was coming from the 5.7 Shurflow water pump. No water was on but the pump was running (pump was very hot so I had been doing this for some time) but not pushing any water. What gives. Anyone have this problem and have an answer. On an old motorhome, a pump I had did the same thing and it was a bad pressure switch. I understand that the 5.7 doesn't have one so I am at a loss. I did hit it and it stopped and did not run until someone turned on the water inside and after they turned it off, it started running again.

If the pump is the original pump then it has an electronic pressure switch and the pump will need to be replaced. If it is one of the newer pumps it has an adjustable pressure switch which you may be able to get working correctly.

If you look at the pump head you will see four screws holding in a plate that is about 1.5" X 1.5". If there is another screw in the middle of the plate then the pressure switch is adjustable. Turning that screw a turn in both directions then returning it to the original position MAY solve your problem, but you need to monitor the pump for awhile to make sure.

Ken Tarkin
2005 34' Alpine

ernieh · 02-03-2010, 10:45 AM

Does anyone reading this thread have a 5.7, AUG 09 or newer that has failed?

EngineerMike · 02-03-2010, 04:13 PM

My pump, like its owner, is a little slow on the uptake. I open the tap which drains residual pressure, then have a once second wait till the pump comes on. If I change flow control significantly, again the one second zero flow wait, then the pump resumes. I haven't fiddled with it yet to see if the center screw adjuster will fix that or destroy the pump altogether. Can't wait.

Jim A · 02-03-2010, 05:15 PM

Happycamper1,

Recently the tank fill valve on my coach went haywire, and that allowed the pump to run and recirculate water to the tank, similar to what Wayne describes. It leaked and would not shut off the water flow. The same condition will slowly fill and then overflow the water tank if you are connected to city water. I would suggest connecting to city water for a while and see if your tank fills. If not, then replace the pump.

I also have had two of the 5.7 pumps go bad. First they began to run continuously and then they stopped completely. The third one seems to be doing better, so I think the factory's earlier problems might have been fixed with later pumps as implied above. Or it could be just luck because I am prepared and carry a spare pump ready to plug in case of a failure!

Big Bear Local · 02-03-2010, 05:43 PM

Mine only pulses in the bathroom sink. Not in kitchen or shower or toilet ???

Jim & Ingrid McIntosh · 02-03-2010, 09:18 PM

ernieh,

We have had at least two 5.7's with October and November 2009 dates fail in less than two days. Pump #9 (since Dec 2009) is scheduled to be installed tomorrow. We've given up on the 5.7's and are going w/the 3.5 (no sensor) and an accumulator tank. Will keep our progress posted.