Trim pump runs and fluid flows but no movement?

[thedukeryan]

I have a 75 mercury 850 with hydraulic trim. I went to purge the air out of the system thinking it may be the problem. Doing one at a tim I removed the bleed screws on the top and ran the pump till fluid sprayed out. Then I removed the cylinders and flipped them over and did the same with the other bleed screws. Put the screws in, filled the resevoir and ran the pump. Still got nothing. Would the next option be replacing the cylinders? I have another 850 that I was thinking about pulling the cylinders off and switching. Just don't wanna go that route if there are easier options out there.

 

[rosser1]

Re: Trim pump runs and fluid flows but no movement?

after bleeding , did you put more fluid in?

 

[thedukeryan]

Re: Trim pump runs and fluid flows but no movement?

Yep... Added more fluid.

 

[*EdC*]

Re: Trim pump runs and fluid flows but no movement?

You may have a valve problem at the pump, or the cylinder seals need replacing. I'd first try disconnecting the cylinders from the motor. (no weight on them) and try that. Hope that helps

 

[monk-monk]

Re: Trim pump runs and fluid flows but no movement?

You probably have a defective control valve (the part the lines screw into on the bottom of the pump). When you took the bleed screws loose the fluid had a "free" path, when you hook the lines up the pump is not able to lift the rams because the pressure required to do so is being lost in the pump valve body.

 

[thedukeryan]

Re: Trim pump runs and fluid flows but no movement?

That makes since. Can the valve body be replaced or am I better off just finding a whole pump assembly? Or maybe I should justleave it and raise/lower it manually. Also this may help someone diagnose it. The first time I purged the air I got no movement so I tried turning the big thumb screw at the bottom of the pump all the way out or in... Can't remember. Anyways I ran the pump some more and then all of the sudden one of the hoses busted loose. There are 4 hoses coming out two braided and two rubber. It was one of the rubber ones that busted loose. I think the knob I turned closed off the valvle causing one of the rubber lines to build up pressure till it came loose. The line was not damaged and just needed new hose clamps. Does that help at all?

 

[monk-monk]

Re: Trim pump runs and fluid flows but no movement?

No, the thumb screw at the bottom had nothing to do with the line popping loose. That thumb screw should be turned all the way out (counterclock-wise). The thumb screw is a pressure relief valve, when turned all the way out it holds the motor down in forward gear, when you turn the thumb screw in you relieve the down pressure and if you tried to run the boat forward it would raise the motor instead of pushing the boat forward.

 

[monk-monk]

Re: Trim pump runs and fluid flows but no movement?

My mistake, not forward gear but in reverse the motor would raise. Its the reverse lock-down mechanism.