Fresh Water Pump

[Viper]

The pump on the 355 is way more accessible than my 3807. Mine is under a little hatch about 6" by 10" which is under the last step leading down to the galley. You have to squeeze your head under the step to see what you're doing with the one hand you can get in the opening. The plan is to upgrade the pump but installing it on the other side of the bulkhead for easy access in the engine compartment.

[km1125]

I second the suggestion to take it apart and clean it. I've done that with several with great results. With many you can even buy new head parts instead of replacing the whole thing.

I've also gone the replacement route too, and got burned. Put in a very nice "soft start" pump to replace my old one and it failed not too long after warranty ran out. It was expensive too.

What you buy new may not necessarily be better than what you have, nor last longer. You have to do some assessment of what you're starting with.

[gmac98004]

Hi Everyone,

I appreciate all the comments thus far.

I've done a lot of fussing and cleaning around my 355 and I've never seen a dock side water inlet. Where would it be located on a 355?

Lastly, could a failing or not pristine rubber gasket on the port side standard water tank fill cap be a root cause?

All your help is wonderful!

Stay Safe, Greg

[tomschauer]

For the dockside water it should be on the starboard side of the boat a couple feet above the surface of the swim platform. Just above the transom shower if you have one of those.

And, no, the fill cap will have no effect on the pump operation.

[gmac98004]

Hello Team!

I have some updates on my crazy fresh water pump installation:

1. Bought a virtually like for like Shurflo pump to replace the LOUD and potentially defective original unit. (4138-111-E65. 3GPM, 55PSI)
2. Access to the pump was actually easier than I anticipated. The approx. 20” x 20” removable panel in the aft cabin wall provided just enough room for me to get access and removed/install.
3. The pump was installed only about 6” from that panel, so although tight, allowed me to get good vision of the area as well.
4. After some fuss and far too much overthinking, the unit was fully installed and worked.
5. Unit no longer pumps every 5 minutes when faucets are not in use!
6. Unit is quieter than previous unit. Using my decibel meter app, old unit ran at about 53db and new unit runs at about 48db.
7. No significant leaks detected…….initially.

The systems runs with pretty good water flow. But when a faucet is opened, there is air trying to work its way out of the system. Some huffing and puffing. I’ve purged all lines including vacuflush systems A LOT…and at various times! Water tank is about 1/3 full, so there is plenty of water in the system.

After leaving the pump on overnight, I noticed a drip in the white PVC 90 degree connection from the pump to the PEX. (Photo is of old unit but I’m leaving that PEX in place for simplicity and to rule out any flaws.) I’ve tightened that connection at the pump to the point I can’t turn any longer and fear of breaking a connection. I’m hoping that my air problem is related to that leak.

I know Shurflo is very keen on ensuring that connections to their pump are hand tightened.

So my question to the group is, what fitting and tactic should I use to remove and replace that 90 degree connection and ensure a leak free pump? I’ve looked at a lot of elbows online and I’m not certain if any of them are actually made to work with a PEX to a threaded male connection. I've looked at a lot of connections and am thinking of something like this. But would it work on PEX?

https://www.westmarine.com/shurflo--por ... 32_002_002

Would love to use the Shurflo wingnut design to make it a tool free install/uninstall but will take what works well.

Thanks for listening to my story and hopefully I can knock it out this week!

Stay Safe, Greg

[Midnightsun]

Pretty sure those older elbows were meant for 15mm tube as opposed to 1/2' PEX seen in the picture. That being said, this looks like it would work, at least the PEX side will. https://www.acehardware.com/departments ... gs/4165684

Air in the system is never on the pressure side as it is flowing pressurized pumped water, if there is a leak on the pressure side, it will drip water not suck air.

Air can be caused by 2 things, a leak in the suction side or cavitation. I see you have a small filter on the intake side. Is this a coarse enough filter to prevent restrictions? Is it clean? If the answer to any of those 2 was no then this is most likely your problem. Those filters are meant for large particles such as pieces of teflon tape, and usually consist of a rather large screen a little smaller than your typical window bug screen. If this filter is replaced with a finer one, there will be issues of cavitation. Rule of thumb is to never restrict flow on any pump intake.

[bud37]

Just to add, looking at the pics it looks like the factory screen filter on the suction side, it needs to be clean and the lid fitted correctly as there is an O ring seal there.....I would lose the double clamps....they are just not needed there and can actually create leaks if on fittings not designed for them.

I know you said you have flushed all lines....both sides hot and cold, transom shower etc etc. Fill your water tank just in case your gage reading is off.

[tomschauer]

What thread sealant did you use?
Teflon tape?
If you didn't try some, or a bit of silicone on the threads.

[km1125]

Is the pump inlet higher than the water level in the tank? If so, then it's REALLY important that all those connections between the tank and pump are sealed good. They won't leak out water if they're higher than the current water level, but will leak in air, as the pump has to pull the water UP from the tank. My pump was actually located BELOW the bottom of the tank, so this was not an issue for me.

[gmac98004]

Hi Team,

Just a few clarifications from your questions above.

1. The pump inlet is nearly exactly the same location as the factory location. (within a ½”). So don’t think that would be the cause of my issue.
2. I just called Shurflo, and spoke with the tech rep. The new strainer I put in line to replace the original bulb type strainer is exactly what they recommend, so they don’t think that would be a likely cause.
3. Lastly, in order to replace the white 90 degree elbow with the part that Midnightsun recommends, would I need a PEX expander flairing tool to do that???

All of your help is tremendous and I’m so grateful. Hopefully we can get this conquered!

Take Care, Greg