Fresh water pressure problem

[MikeP]

I'm looking for ideas on what I may be overlooking, I have a leak in the freshwater pressure system somewhere. Periodically the pump will activate to maintain pressure in the system. This has been occuring since I have owned the boat but I finally decided to investigate.

In approximately 35 minutes, with NO water turned on anywhere in the boat and the pump turned off so it will not automatically activate, the system pressure will drop from 40PSI to 28PSI. I can not find any water leaks so far. The pressure is shown on the pump-mounted gauge. Here is what I have checked:

Washer in the forward cabin - all fittings completely dry.

Sink and shower fittings in all 3 heads - all fittings dry

Galley sink - all fittings dry

Refrigerater (icemaker) - didn't check the fittings but there is no water on the galley floor under the frige.

Aft Deck Bar sink - all fittings dry

Aft deck icemaker - all fittings dry

Windshield washers - no dripping from nozzles, no water dripping from lower helm overhead console (didn't open console).

Aft deck fresh water washdown faucet - no dripping; I haven't checked the actual hose fitting to the faucet (haven't even found access to it yet) but there is no dampness on the water hose to the faucet and the aft bilge is dry as a bone.

Water faucet in engine room - fitting dry

There is no water showing up in any of the 4 bilges (forward, two eng rooms, aft); heads are sea-water


I welcome any suggestions as to where the heck the pressure is going or how it is going without leaving any water anywhere.

Thanks

[Avenger]

Any check valves in this system?

[Liquid Asset]

Just thinking out loud here, but could this be an internal pump problem. What if your pump is leaking the water backwards into the fresh water tank.

The other possibiliy is that a fitting is leaking somwhere that is not readily avaliable to see. My system has a very slow drip at the hot water heater and I have not had the time to fix it yet. But what I have found is there are many fitting in the system because they used copper lines. This could be a problem since any one of those fittings could potentially leak.

[Trojan]

I would check the check valve on the fresh water pump. Sounds like its leaking back through the pump. A common problem in older pumps. Some times you can just clean them. Depending on the type of pump. Some are just a rubber flapper type check built into the pump and you need to purchase a complete rebuild kit for the pump. I had to do the complete rebuild kit on my last pump. I think it was right around a $125. About half the price of a new pump. Plug the output of the pump just after the pressure switch. Cycle the pump and see how long it takes to blead off the pressure. It should not bleed off. If you can't find a physical leak in the system. It has to be in the pump. You could add a ckeck valve between pump and the pressure switch for a cheap fix if there not one there now. Most gear pumps have swing check or a ball check. Good luck. Bill

[34Hatt]

My system was always tight then one spring same thing pump cycles found a small piece of plastic in the pump check valve cleaned it and its been great since. If you can't find it, can you some how cap off section of the boat to narrow it down?? You have a lot of hose and fittings and if you can do it by process of elimination. I think this one might take some time if it not the pump.
Good Luck

[MicroKap]

My icemaker will continue to use the water pressure in the lines to make ice even if the pump is off. I hear the water pump turn on periodically when the ice maker is on. Start with the simple ideas before going crazy.

Larry K.
1980 60' Sportfish
Monmouth Beach, NJ

[MikeP]

Hmmm - there are two icemakers and I had totally forgotton that they will be periodically opening their water valves. That's a possibility but I BELIEVE the pump cycles more often than the icemakers do..

I can isolate the system between the fresh water tank and the pump. There is a shut-off valve right at the pump to isolate it from the tank supply. I'll try closing that and see what the pressure does.

I haven't noticed a check valve installed in the system but I assume there is/should be one. I haven't really looked for a valve so I'll do that carefully when I go back down to the boat later. I'll also check the oem Hatt diagrams to see if one is shown.

Thanks for the excellent suggestions!

Is this a great forum or what!

[Fanfare]

Check the volume of water needed to lower the pressure from 40 psi to 28. Most systems are set up to come on at, say, 20 psi and pump the tank up to 40, then shut the pump off. An air cushion keeps the pressure on for the water system until it drops down to 20 again, then restarts the pump. This cuts down on run time and therefore wear on the pump. It also dampens the pulsations of the pump and helps quiet it. But the quantity of air can decrease, either from leaks or simply from dissolving in the water. At one time the pressure tanks just had the air in a bubble on top of the water. Newer tanks have an inflatable rubber bladder inside, and seem to lose air much more slowly. But each needs to be recharged from time to time or the pump runs too often. If your system is like this there will be a tire valve somewhere around the tank to refill the air. Turn off the pump, open a faucet, drain until the pressure drops to near zero. Recharge air per tank instructions or try 20 psi for starters. Then close faucet, refill system and test. Adjust air pressure as required to give reasonable flow between pump cycles.

Jim Grove, Fanfare, 1966 50MY

[Nonchalant1]

Mike,

I think Jim Grove has got it. A searay had that problem near us and it turned out to be low air volume in the captive air tank. then it takes very little to reduce the pressure.

Doug

[hattitude]

One other simple thing to check...

I had the same problem with my 46C. The cycling pump drove me nuts, but no water could be found. Turned out that the check valve for the dockside water inlet was leaking pressure. I finally found a small amount of water leaking back out the inlet fitting. I added a small valve at the inlet and problem solved......

Good luck...