OX66 Tilt issue

[ohsoslow]

Hey guys,

Have been searching but failing to find an answer to my problem.

I've got a 1997 OX66 225hp, and lately the tilt ram seems to have lost it's holding ability. It will tilt motor all the way up and down fine, and will hold it up for a decent amount of time (will drop maybe 1/2" over a week sitting on trailer).

BUT, when out on the water, if I reverse to hard, the motor will fly up out of the water, and if I put power on when in forward and motor tilted up a bit, the motor will drop down onto the trim rams.

Is this normal? (I've never noticed happening before) And if it's not, whats the likely culprit?

Thanks

[Sequoiha]

it seems like you have an internal leak, allowing the fluid to bypass,

[rodbolt17]

most likly the tilt piston or free piston is leaking.
could be the two way check valve.
could be leakage at the manual release valve.
my first look would be at the tilt piston shock valving and the free piston valve.

[ohsoslow]

Thanks for that guys, the replacement seals and free piston seem pretty cheap, so think I'll give it a strip down, and freshen up, and see if that helps. I did notice when I checked the fluid it looked a little milky, and it looked like maybe fluid leaking out of trim units, so will replace them at the same time.

Rodbolt, while I've got you here, whats your thoughts on running NGK 8 range spark plugs instead of standard 9 range? I'm currently spending my days *****ing under 2000rpm, and after 5-7hours the plugs are fouling up.. I'm running yamalube, and have checked and adjusted oil rod.

Thanks

[rodbolt17]

I would not.
I would monitor CDI output voltage.
we did see the older stators that as they heated up charge coil voltage would fall leading to random cyl plug fouling.