boat lift motor problems

T

toyterrific

New Member
Jul 9, 2012
14
SML
Boat Info
1997 240 Sundeck
Engines
5.7 Mercruiser, 260 hp
Been lurking for a year now since I bought my 97 240 Sundeck.
Pulled into slip Saturday, raised lift enough to hold boat stationary, let my passengers off, then tried to lift out of water and the motor just hummed. Won't go up or down. Both pulleys and the belt will turn by hand. AO Smith 3/4 hp motor.
Called one dock specialist to take a look, he says $675 for a motor and switch before he even comes out. (I can buy both for $250 delivered, so he is a bit too high) I was thinking just start capacitor or spraying some electric motor cleaner as it is not a sealed motor.
Any thoughts/experiences?

Thanks.
 
I'm assuming that both motors are humming hence the lift won't go up or down? The starting capacitors do go bad but I doubt both would go bad at the same time. They're cheap. Did you meter the incoming voltage to make sure you were good?
 
The first thing I do when an electric motor won't turn is rap on it with a hammer. That's the current work around for my outdrive hydraulic motor at the moment. Don't go to town on it, just a few light taps......
 
Single motor on my lift
Going back to lake Friday. I'll try the hammer tap and get a voltage reading at motor.
If still non-functional will remove motor and drum switch and take to repair shop I know where I live. They've been repairing electric motors for forty years and don't think the motor failed. I'll post how it all shakes out.
Thanks guys.
 
If it's a single motor lift and it humms when you go to start it up in either direction the starting capacitor may be bad. They are not expensive and an easy fix.
 
Bucit said:
If it's a single motor lift and it humms when you go to start it up in either direction the starting capacitor may be bad. They are not expensive and an easy fix.
Click to expand...

Funny you say that regarding the hum but no action. That happend to the fan motor in the outdoor part of the unit on my dads AC/heatpump last Saturday afternoon. The guys came out and checked it and it was that capacitor. It had kind of "bulged out" at one end. That may be one way to tell, though not scientific! :) Where would that capacitor be in a lift. I'm visualizing my lift with the shroud taken off. There's a big cog wheel connected perpendicularly to a drive gear that has a belt at the end, which is belt-driven by the "football" sized electric motor. I guess the capacitor would be inside the motor?
 
Happy Ending!
Took 3/4 hp AO Smith motor and lift switch to electric motor repair shop that has worked for me in past. Cleaned dirt caked motor, mud daubers loved it in there, wired up and everything checked out fine. Just installed this morning and lift works like a champ. My cost was $48 and two hours of my time. Maybe I should start a side business and actually troubleshoot and repair dock llifts rather than just changing out motors and switches like everyone else around Smith Mountain Lake.
 
Seems saga not over. I posted after watching my sundeck rise out of the water for the first time in two weeks only to find out later that it trips the circuit breaker immediately upon trying to lower the boat. Obviously still have some work to do.
 
JimFromMD said:
Funny you say that regarding the hum but no action. That happend to the fan motor in the outdoor part of the unit on my dads AC/heatpump last Saturday afternoon. The guys came out and checked it and it was that capacitor. It had kind of "bulged out" at one end. That may be one way to tell, though not scientific! :) Where would that capacitor be in a lift. I'm visualizing my lift with the shroud taken off. There's a big cog wheel connected perpendicularly to a drive gear that has a belt at the end, which is belt-driven by the "football" sized electric motor. I guess the capacitor would be inside the motor?
Click to expand...

The capacitor will be mounted on the motor. It will have a cover over it. It's probably 4 -6 inches long. You can't miss it. It will look like a bratwurst covered up mounted to the motor.
 
It could still be the CAP. On an Electric motor one of the functions of the capacitor is a "Soft-Start" function. It would limit the in-rush current of the motor at initial turn on. If the motor was really dirty, and it got pretty hot, I would certainly look at the cap. The bulge is a dead giveaway, but not the only one. These are big caps. look for the Dielectric compound to be leaking. Of course your guy just cleaned all of that up, so it may be all gone.
A pregnant CAP is BAD. Regardless. Get another with the same rating or larger. uF should be the same, but voltage rating the same or bigger. We engineers over-estimate most things, but with caps you have to be careful. You can go too big.

Does it function in one direction without tripping the breaker, but not the other?
 
Sounds like a capacitor issue or a centrifugal switch issue.Start capacitor is easy as stated above by others here.
Drum controller simply changes polarity on the start windings.
Centrifugal switch allows start windings to energize in parallel with the run windings. Once at a pre-set RPM the centrifugal switch opens, stopping current flow thru the start windings. Motor carries on with the run windings.
You stated earlier the motor was pretty dirty. Chances are you might have some dirt in the centrifugal switch preventing it from closing.
Trying to start on run windings only will give a good hum & trip the breakers or overload devices out.
 
Now we're going up and down!
Electric motor repair shop wired up drum switch and motor and showed me it worked both ways. Left only the wiring to be the problem. Replaced my 5 conductor wire and it runs like a champ. Don't understand why though as I switched wires all over the motor and switch and it would always lift up but never go down.
Anyway, total cost for repair was $48 for motor cleaning, $35 for wire, and about four hours of my time. Still much better than $650 to replace everything.
Thanks for the input fellas.
 
Need help have a boat lift boss motor. I installed it yesterday and when I power it with the key/remote it turns about 1/4 turn and then kicks out. I turn the key off and back on and it will do the same thing. Does it both up and lowering. Anyone able to help please?

Thank you in advance.
 
Glad you got it working - I had similar issues with my old boat lift (A Doozie Boat Lift) and it turned out to be the drum switch. The motor itself hardly ever goes bad.

My new boat lift acts up sometimes too - I just have to wake the driver up and all is good.
 
DarkJester said:
It could still be the CAP. On an Electric motor one of the functions of the capacitor is a "Soft-Start" function. It would limit the in-rush current of the motor at initial turn on. If the motor was really dirty, and it got pretty hot, I would certainly look at the cap. The bulge is a dead giveaway, but not the only one. These are big caps. look for the Dielectric compound to be leaking. Of course your guy just cleaned all of that up, so it may be all gone.
A pregnant CAP is BAD. Regardless. Get another with the same rating or larger. uF should be the same, but voltage rating the same or bigger. We engineers over-estimate most things, but with caps you have to be careful. You can go too big.

Does it function in one direction without tripping the breaker, but not the other?
Click to expand...
Actually, in an induction (brushless) motor, a starting capacitor is required to provide an Alternating Current phase shift (call it a delay in current application) at every other stator pole creating an angular offset in magnetic forces to allow the rotor to begin turning on it's own. Without this phase shift the magnetic poles of the stator and rotor elements will not develop necessary attracting and opposing forces to start the rotation. A start capacitor is not designed for continuous use but rather provides a simple delay of high current to the next magnetic pole of the motor; consequently, there is a centrifugal switch that when the motor is below a certain RPM the switch is engaged and allows the start capacitor to apply a delay in current and thus start the motor's rotation. After the motor achieves a given RPM the centrifugal switch disengages and the motor's inertial forces keep it rotating. So, if the motor is "humming" and not rotating either the capacitor is bad or the centrifugal switch is not engaging. Both easy fixes. And FYI, that "clicking" sound as the motor spins up is the centrifugal switch disengaging.
 
Last edited:
Hey Pete,
Can you turn anything by hand? Is everything "free-wheeling"? If things are binding then it might be shutting down because of over-current. See if it will free run without anything attached. Always start at layer one. Check your voltage, see if it will run no-load. Do some stuff before you call anyone. The world is full of guys that just swap parts for a living.
 
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