89 90hp trim won't stay up

[tblentrprz]

Greetings and thanks for helping. 89 Mariner 90hp 3 cyl trim/tilt configuration. The tilt stays up but trim slowly drops. Originally the system had leaks and wouldn't hold pressure nor stay up. Replaced all seals in trim and tilt cylinders, seals on manaul valve and in pump, replaced tilt check balls and springs. It seemed the system worked fine for about 2 hours and then the trim setting would not hold. No external leaks. I have not replaced the left trim piston assy (that includes check valve). Would like to understanf how to isolate the root cause and repair/replace what is necessary. I have an authentic Merc/Mariner Service manual but no info provided to isolate this issue. If I had to guess, I would think that the trim rod/valve has a problem. It is not serviceable. Not crazy about spending/gambling $150 without knowing. Any thoughts? Much appreciated. BTW - Did a search on this forum and didn't find any info. Also, posted this issue on another forum without receiving any replys. Thanks for taking the time to reply.

 

[WillyBWright]

Re: 89 90hp trim won't stay up

Could be that valve, or a trim piston O-ring. Contamination is a common cause for sticky and leaking valves, usually lint. Cleaning is all it usually takes to handle that. Use paper towels when working on any internals. Cloth leaves lint that eventually finds someplace to cause problems. Paper fibers break-up easier than cloth fibers. Nice thing about trim rams is that you don't have to do anything to get at them except tilt the motor. Most everything else requires considerable disassembly.

 

[tblentrprz]

Re: 89 90hp trim won't stay up

Thanks WBW. Yea, not to difficult to pull the left trim piston and inspect the check valve and oring. Sure would have been nice if it was designed to be serviceable. Maybe some solvent or heat would allow the retainer/seat to be removed and inspected along with the ball. I'll have to experiment. Thanks again.