50TLRA tilt/trim issues

[jar0023]

New guy here so thanks in advance. I did a search and could not find what I needed.

I'm the second owner of a '02 50TLRA. I'm having tilt trim issues. This motor has single cylinder tilt/trim system. When stationary or at very low speeds the tilt/trim works fine. When the boat is under load the motor will bottom out against the stop. It will hold its position over night in the driveway but won't hold position under load. I do understand if I have the motor up into the tilt range it should drop down to trim range but now it bottoms out completely. Blows through trim and bottoms comepletly. I purchased the boat last spring and it has gotten progressively worse over the last year. Also it appears that someone has worked on they trim cylinder as they boogered up the spanner holes. I've priced new and reman units but would like to fix his myself if possible.

Can anyone give me a diagnosis over the net?
Is is possible to rebuild this unit (pump/cylinder)? I'm a competant mechanic. I've rebuilt revalved shocks before. I just don't have any boat experience.
Can someone point me towards a rebuild kit?
Where is the best place to buy a shop manual online?
Thanks again
JAR

[boats.net]

It's probably a valve not holding pressure, bad main valve, up or down relief or shuttle piston. It would have to disassembled cleaned and replace valve seats or valves. There is no kits available, you get parts as needed. You can order service manual at www.yamaha-motor.com.

[jar0023]

Thanks,

At less than 5 bills, a complete reman unit is starting to sound like the way to go.

JAR

[Bay Catt]

You can rebuild yourself. Take extra care with cleaning. Hydraulic systems should be ultra- clean to perform properly. Also flush the entire system with mineral oil before you disassembly.

[jar0023]

Thanks again guys. Keep the advice coming. I've got the shop manual coming. I'm going to have a go at a rebuild before I buy a new unit. I can't make it any worse. I found out yesterday I have a business associate who can get me parts cheap. I won't be out much for valve/seats even if it doesn't work out.

Also he put me in touch with a mechanic who told me to take the manual release valve all the way out (remove snap ring). He said many times this is were the dirt/debris will be. Anyone here have an opinion. Should be easy enough, hardest part will be getting boat back in the water to test it. Gonna be in the high ****s tonight. That's real cold for MS.

JAR

[cyrillefrenchy]

ok great, keep posting, i would like to know what you found.
frenchy

[jar0023]

Update

Ordered manual from Yamaha. I gets here and the tilt/trim mechanism in the manual is not the one on my boat. Erica at Crestec is still trying to find me a manual with the correct schematic. Probably not a big loss as there is not much info beyond order of removal of parts in this manual.(as far as tilt/trim is concerned)

I have good schematic from online so I tore into the unit this weekend. It's realy not as scary as the shop would make you think. Some sedement in the fluid but looked as if filters were doing their job to keep this out of pump. Appears my relief valve seal has hardened and is sticking in/against the orifice it seals with. I have seals coming and will replace all since I have the unit apart.

There is an adjustment screw and set screw that allows you to adjust the tension on the relief valve spring. Any boat mechanics want to weigh in on this. If not I'm going to reinstall as set. I'm wondering is increasing spring pressure would help motor maintain trim setting under load.

JAR

[panamageorge2]

Im guessing since you already have the unit apart you didnt count the number of turns when you took the adjustment screw out for the relief valve spring?
If you havent taken it out yet just count the turns.

[jar0023]

I haven't made any adjustments yet. There is actually an adjusment screw and a lock nut that keeps it in place. It doesn't have to be removed to r/r the seals. I curious as to whether adjusting it to increase the spring pressure on the relief valve would help keep the trim from saggin under heavy loads.

JAR