50hp mercury tilt trim pressure problems

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rockymercury

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I have a 1980 1/2 50 hp mercury thunderbolt with hydraulic tilt and trim SER# 8069225 MAde in Australia. i am having trouble with the trim pump not holding the motor all the way up or up at all but it will raise the motor to full tilt, but will not hold it there as soon as i let off the button it falls down pretty fast . i have checked the cylinders they are not leaking and the seals are good. the pump has only one selinoid on it. Is there something i can check other than the seals. i am not mechanically inclinded though on a tight buget (SET BY THE WIFE) and i want to get it fixed as cheap as possible or fix it myself. can anyone tell me how to break the pump down to see if it is the valves or the O-rings and if so where can i find replacements for it. I found these number s written on the side of the pump 92975A1 and it has a manual release vavle on the front bottom of the pump under the resevoir any help would be appreciated thanks Rocky rocky577@msn.com
 
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Laddies

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Re: 50hp mercury tilt trim pressure problems

rocky, is the manual tilt vavle turned all the way out, before tearing into the pump first remove the lines from the cyls. and flush the system wita very light oil by running it up and down, if that don't work you can tear the pump down, keep in mind that the only part that you can buy is the large o/ring that seals the pump to the reservoir, the pump can be disassembled and cleaned just do not turn the studs that hold the pressure relief spring inless you keep track of the number of turns, good luck
 
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rockymercury

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Re: 50hp mercury tilt trim pressure problems

I checked the valve and it is closed according to the inscription on the side of the resevoir. I have since taken the thing apart and I have found that at least one of the O-rings are bad. I also found milky oil in the check valves as well. The question is even though they don't make a rebuild kit for the pump or vavle can i buy a box of hydraulic O-rings and match them up or were the O -rings a different diameter than the ones sold in a box. Can anyone help me with that also i found that the hydraulic lines, well lets say they seen enough sun to see through part of them so that could also be a problem replacing them as well.
 
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rockymercury

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Re: 50hp mercury tilt trim pressure problems

found a site that sells the internal seals for the pump going to try and get some of them and replace the worn seals
 
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