Slow trim down plus sticks at halfway

[muskyfins]

2000 Rinker 270FV
5.7 Mercruiser
Bravo 3
Trim runs slower than normal on up stroke and extreme slow on down stroke. To the point, hydraulic motor will go into thermal protect and I have to wait until cool. Plus at around the halfway point in the stroke (both up and down), she almost stops and seems to struggle.

I have already checked all electrical connections. I replace my hydraulic oil every year so I don't think it's a sludge issue. (but I haven't disassembled pump to confirm) Is it possible there is a bad seal in the rams allowing fluid bypass internally and causing pressure build up that doesn't allow it to move?

As always any and all suggestions appreciated.

 

[dubs283]

Sounds like either a power supply issue or the motor itself is failing. Battery full/good condition? There are multiple electrical connections on the trim pump assembly itself that are prone to corrosion as well

 

[muskyfins]

Battery full. Excellent condition. (happens even when on shore power)

All electrical connections clean and tight.

I have always heard these pumps very rarely go bad, but then again, I have bad luck

 

[dubs283]

I have always heard these pumps very rarely go bad

True, but they do fail time to time. I'd take the motor off, remove the end cap and clean the brushes/commutator. Might get a little more life out of it

 

[muskyfins]

SOLVED!
I had to take a guess because boat was in storage. I guessed rams, but I was wrong. So after installing $1200 worth of Mercury trim cylinders, I ordered and installed a new pump assembly.
Bingo.
Could immediately tell the difference in motor speed just by sound. Trim works smoothly in both up and down directions. Motor doesn't struggle at any point in the stroke.
As I said, I am the unlucky guy who has the 1 in 1000 pumps go bad.

 

[Scott Danforth]

Was it the pump or the motor. Usually the motor is what goes

 

[muskyfins]

Was it the pump or the motor. Usually the motor is what goes

I'm thinking motor itself. I am planning a disassembly of the valve body for fun. I suppose it could be a problem in there like a bad check or something. If the pump was worn or even leaking internally/cavitating, the motor should have still had much higher RPM.