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Power trim issue - rebuilt cylinder - still sinking/won't trim up

gixxer00k

New member
I have a 1996 Force 120 outboard that had a hydraulic leak out of the top of the trim cylinder where the trim rod comes out of the cylinder. I bought a cylinder rebuild kit and replaced the o-rings in the trim cylinder. Re-assembled, topped off with trim fluid, ran the trim up and down several times, and topped the fluid off again. No more leaks, and everything was working great.

Took it to the lake and after about 30 minutes the trim refused to go up. Got it home and re-checked the fluid level. When I released the fluid fill plug, it had quite a bit of air pressure expel out and the fluid seemed a bit watery. The fill plug threads were shot, so I ordered a new one and installed. Engine trims down fine, but won't trim up. When I push the trim up button the motor runs, but the cylinder doesn't move.

Disassembled the cylinder last night, but couldn't identify anything unusual. O-rings all seem to be fine. The only o-rings I haven't replaced are the ones that go in between the valve body and cylinder. At this point I'm not sure what the issue could be. Any thoughts?
 
Usually if the trim leaks down??
There is a poppet kit that might help? 893913A02
No?
Then the pump will probably need replacing.

I might be wrong so get the factory manual for your motor?
1996 97 98 99 should have the info on the pump rebuild??
 
That poppet kit is for the Design II. I should have mentioned I have the Design I:

https://www.boats.net/catalog/mercu...-0e202999-1996/power-trim-components-design-i

Similar kit for my unit appears to be item # 6 from the above parts diagram, which is now P/N 811678A 6:

https://www.marineengine.com/newparts/part_details.php?pnum=MER811678A+6

I'm considering biting the bullet on this kit to see if it fixes the problem of the engine slowly sinking (not holding pressure). If the o-rings in the valve body were bad, would that also explain the engine not trimming up at all? I'm wondering if I have 2 problems: (1) bad o-rings in valve body (2) worn brushes in motor?

Unfortunately the only way I see ahead is to order the valve kit and hope it fixes the problem. Next I would think the motor? New trim cylinder & motor assembly is about $1k, which is crazy.
 
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