Noisy water pump

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pgtips

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After posting previously about my noisy water pump I thought I'd do a bit more investigating today.

Went down to the boat and was going to take the pump off so turned the water valve off at the tank. Then turned a tap on which made the pump run and it was quiet. Opened the valve at the tank and pump was then noisy!

Basically, when the pump is just running its quiet, but when it's actually pumping water it's noisy. Why should this be?

I do have an accumulator fitted which I'm not convinced is doing anything as the pump runs all the time when a tap is opened and my understanding is that the accumulator should mean the pump doesn't run all the time when taps are opened.

Any ideas??
 
When the pump is loaded it is noisy, when it's unloaded it is quiet. Sounds like bearings to me, or some other mechanical fault to do with the swash plate.

Set up your accumulator like this. Open the Schrader valve at the top and let any air in there out. Open a tap with the pump on. The pump will run constantly. Now begin to pump air into the accumulator with your bike pump. Note that the water pump will begin to run intermittently. The stopped periods will increase as you continue pumping, until eventually they will begin to decrease. Now stop pumping, release a little air from the Schrader valve until the stopped period is at its maximum. Turn the water tap off and ensure that the pump remains stopped. If not there is a leak somewhere, should be obvious, or there is debris in the valve(s) of the water pump.
 
If it is the simple type of accumulator, with no diaphragm or valve, it needs to be emptied occasionally. Do not half-fill it with water. The water pressure compresses the air, so water goes in and out of the accumulator, as required.
 
Thanks for the replies so far.

There is a screw in plug on the top of the accumulator (Jabsco 1 litre) which I started to unscrew and water came out of the top, so put the plug back in. I'm not sure that there is a valve in there, so perhaps I just need to do as NormanS has advised adn just empty it out.
 
I found the Jabsco accumulator with a tap at the top (no diaphragm) very unsatisfactory. The screw was very hard to tighten, even with teflon lubricant and the casing eventually cracked. The diaphragm type is much less bother, even if it costs more. The alternative is one of these newer self-adjusting pumps, for a price.
 
There is absolutely nothing magic about an accumulator. It is merely an air chamber. On a previous boat, I had one of the plastic Jabsco ones, and if I remember correctly, the plug in the top was tapered, and any excessive tightening could easily lead to splitting the chamber. Moral, only tighten enough to prevent leakage.
 
If I may,

what if you use a home/ch type of accumulator tank? You know the 10-20lt red mild steel ones (complete with a membrane and valve) that cost 30quid compared to 100+ for a 2lt ss marine one?
Will they last long enough to justify the expense?
I guess these larger tanks will be kinder to the pump (and your ears!) so well worth checking.
Anyone tried it?

cheers

V.
 
I'm thinking of doing away with the accumulator as looking at the new Jabsco water pumps most say an accumulator isn't required.

I've also found this pump (Fiamma Aqua 8 iSensor Water Pump) which is variable speed and under £100. Is it any good though? Found on caravan websites so is it cheaper just because its not classed as boaty?!
 
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