Livewell Question

[Fishtales]

I noticed that when the livewell is on it fills about 3/4 of the way up (not enough to start draining through the top of the tube and then the pump appears to get an air lock (hums louder than normal operation) and no water comes in the inlet. If I shut the pump down using the rocker switch and then turn it back on it starts to fill again for a few seconds and then repeats. I have not used the well a lot, but don't recall this happening.
Do you think it is something in the line? The seacock is always closed.
Maybe the pump?

My 282's pump intermittently gave me trouble too. I would take it apart, clean and reseat the rubber mechanism and it would work for about a year or so, then I'd have to do it again.

Thanks

 

[HDGWJOE]

I keep my seacock closed all the time also when I'm not using the well. I've never had the problem you describe. I don't even hear a change in the pump as the water approaches the top of the well.

My guess would be the pump... being it pumps fine till 3/4's full you can probably count on the line being clear.

As a comparison...when my well is filling up it fills up at a pretty good clip(couple of minutes(3 or 4))... pump seems very strong. It's also pretty quite... if I have the lid closed I will forget about it especially if the outboards are running. I usually hear the water running as it's filling but seldom do I notice the pump noise. When yours is working correctly is it similar to what I described?

I'll try to get down to my boat this week and see what type & capacity of pump is on mine... maybe in 2006 they changed pumps. I wonder if Grady has been seeing this problem... might be worth a call to Bert.

 

[enfish]

I would guess the pump as well. As a wild guess as to what's happening, maybe the pump impeller is slipping on the shaft after the head pressure gets to be too much for the pump to handle. This would explain the change in sound, and why it will pump again for a second after momentarily shutting it off since shutting it off would allow the shaft to stop spinning inside the impeller, similar to a spun hub on a prop.

This is assuming the pump is a centrifugal pump (Kodiak or Rule).

 

[HDGWJOE]

I would guess the pump as well. As a wild guess as to what's happening, maybe the pump impeller is slipping on the shaft after the head pressure gets to be too much for the pump to handle. This would explain the change in sound, and why it will pump again for a second after momentarily shutting it off since shutting it off would allow the shaft to stop spinning inside the impeller, similar to a spun hub on a prop.

This is assuming the pump is a centrifugal pump (Kodiak or Rule).

OnoEric... makes a lot of sense. I wonder how these impellars are attached to the shaft. If its with shallow splines(and some are damaged) I could imagine it slipping as pressure builds... but eventually you would think it would strip out completely.

 

[wlewis]

The seacock should always be open when running the pump or you'll burn up the pump.

 

[BobP]

There's not a whole lot of pressure difference to raise the water that much higher. I recall a foot of head equals about 1/2 psig, rounded off.

The pump may be on the way out, perhaps a rebuild kit is in order, save the electrical motor.

We are assuming the line is clear and not partially obstructed.
We are also assuming the voltage at the motor is good. A bad or otherwise corroded connection is all it takes to drop violateg too far.

To confirm, measure both voltage and current while running and when it loads up, compare to spec.

 

[enfish]

I would guess the pump as well. As a wild guess as to what's happening, maybe the pump impeller is slipping on the shaft after the head pressure gets to be too much for the pump to handle. This would explain the change in sound, and why it will pump again for a second after momentarily shutting it off since shutting it off would allow the shaft to stop spinning inside the impeller, similar to a spun hub on a prop.

This is assuming the pump is a centrifugal pump (Kodiak or Rule).

OnoEric... makes a lot of sense. I wonder how these impellars are attached to the shaft. If its with shallow splines(and some are damaged) I could imagine it slipping as pressure builds... but eventually you would think it would strip out completely.

The Rule and Kodiak pumps I've seen have pressed on impellers onto a very shallow splined stainless shaft. Eventually it would strip out completely, but static friction is stronger than kinetic friction, so the impeller can hold on for a little while until the back pressure breaks it free. Once it breaks free, there is no way for it to stick to the shaft again until the pump is stopped.

 

[enfish]

There's not a whole lot of pressure difference to raise the water that much higher. I recall a foot of head equals about 1/2 psig, rounded off.

The pump may be on the way out, perhaps a rebuild kit is in order, save the electrical motor.

We are assuming the line is clear and not partially obstructed.
We are also assuming the voltage at the motor is good. A bad or otherwise corroded connection is all it takes to drop violateg too far.

To confirm, measure both voltage and current while running and when it loads up, compare to spec.

Bob, you're correct there is not much difference in head pressure. But all pumps can only pump water to a certain height above the pump before the back pressure from weight of the water above the pump equals the output pressure. That could be only a few inches above the pump due to whatever reason.

The OP stated his pump changed sounds like an airlock when it stopped pumping. That's why I thought spun impeller.

The interesting thing about a centrifugal pump (again I'm assuming the OP has a centrifugal pump) is that the current draw is proportional to the volume of water it pushes. That is to say, if you restrict the flow on the output side of the pump, thus lowering the volume, you'll lower the current draw. So a normally functioning centrifugal pump will have less current draw when it reaches its maximum head level than it did while pumping water up to that head level. I don't think that's the case for other pump types.

 

[BobP]

Agreed, however, if he has a bad connection in the cirucit , the added voltage drop at the motor terminals can make the difference too. Before going after replacement pump, the voltage test costs nothing and is simple to do, that's why I suggest it. He may also want to pull the pump hose off and hold the dock hose nozzle to it to see if it flows strong with out any back wash.

I had a cracked lug terminal neck at the switch of the horn circuit on my 252G, horn was intemittant and low volume. Replaced horn with new horn, same crap happened, thought new horn was bad. Did some troubleshooting, horn voltage dropped to like 6 volts when hitting the switch. At that time old pump was gone with garbage pickup.

Pumps draw a lot of power and require full voltage. Although I would bet my money on the pump head, the time it takes to verify other parameters is worth it for me. Horn cost me $50 bucks and a few hours of my time. If i had checked other parameters first, lug cost 25 cents and 10 minutes to crimp on new one. You win some, loose some. I lost that day, next time I won't.

 

[HDGWJOE]

I'll bet money one of you two guys has nailed the correct answer for Fishtales. Electrical connections is probably the easiest to check first.

 

[BobP]

If the member is so inclined and has a digital multimeter, can get a decent one with big digits at Sears for 20 bucks, on sale for 10 bucks or 15 - keep it on boat, make accessible but don't break connections at motor - connect leads from meter with some clip leads, set meter so it is in sight from bridge, hit switch. Can do this at dock. Read voltage and make notes while it running to full up LW.

Not everyone is so inclined nor handy to do things themselves, even simple things, then they can just turn it over to the marina mechanics like most do.

I've done these simple things for neighbors in marina many times too, saved them a bootle, gives me some exercise from napping with feet up! Kept it low key though, mechanics don't want to hear about any of this activity.

Pulling the hose off pump to LW and flushing it wth dock hose ito verify clear flow is just as simple, can also pull the inlet side hose and backflush too.

 

[enfish]

If the member is so inclined and has a digital multimeter, can get a decent one with big digits at Sears for 20 bucks, on sale for 10 bucks or 15 - keep it on boat, make accessible but don't break connections at motor - connect leads from meter with some clip leads, set meter so it is in sight from bridge, hit switch. Can do this at dock. Read voltage and make notes while it running to full up LW.

Not everyone is so inclined nor handy to do things themselves, even simple things, then they can just turn it over to the marina mechanics like most do.

I've done these simple things for neighbors in marina many times too, saved them a bootle, gives me some exercise from napping with feet up! Kept it low key though, mechanics don't want to hear about any of this activity.

Pulling the hose off pump to LW and flushing it wth dock hose ito verify clear flow is just as simple, can also pull the inlet side hose and backflush too.

Good advice on getting the DMM. That's a tool I consider a necessity on a boat just like spare fuses, wire, filters, wrenches, etc.

 

[BobP]

HDGW Joe- it wouldn't surprise me to find Grady start referring customer questions over to GG site, especially on troubleshooting and older model info.

Young whipersnapper replacements can't cover questions the older guys retiring or getting early outs at Grady HQ Customer Service can!

 

[HDGWJOE]

HDGW Joe- it wouldn't surprise me to find Grady start referring customer questions over to GG site, especially on troubleshooting and older model info.

Young whipersnapper replacements can't cover questions the older guys retiring or getting early outs at Grady HQ Customer Service can!

:lol: They may already be doing that Bob!!

 

[Fishtales]

Thanks guys. Great advice. Ill get on it this weekend and let you know how I make out.