Ox66 Tilt lifting up?

[Bulls-eye]

guys,

Ive got a 2001 Yamaha ox66 engine with a Showa tilt and trim. Im having an issue with the tilt mechinism not preventing the engine from being lifted when I accelerate or in reverse. It can even be lifted by hand when on the trailer. Using the tilt and trim from the switch works normally. Lifts completely and goes up and down all the way with no issue. I have bled the system and even replaced trim seals ( not tilt as that’s a much bigger project). Any thoughts on why the motor can move in that direction ? I have twins and the other does not do this.

So to clarify: the tilt and trim work properly but the tilt arm is not holding the motor down when force is applied to the motor in any fashion that would life the tilt rod out ( rapid acceleration or pulling up on the motor when it’s on the trailer).

Thanks!

Bulls-eye

[99yam40]

when accelerating in forward there should be force pushing the rams in( motor downward) not up or out.

air in the system or a valve not holding would be my guess if it is not air

[Bulls-eye]

when accelerating in forward there should be force pushing the rams in( motor downward) not up or out

I agree but when i accelerate rapidly the push of the water on the lower unit pushes up this motor vs it’s twin next to it which does not.

Thanks

[99yam40]

if both motors are running and both pushing the force of the prop pushing against the lower unit should be greater than the water sliding past.

if the motor was not in gear and running at the same RPM as the other motor, then it could be pushed up by the water running by

[DennisG01]

if both motors are running and both pushing the force of the prop pushing against the lower unit should be greater than the water sliding past.

Yes. The force of the prop (in fwd gear) far exceeds the pressure of the water against the gearcase as the boat is moving. Same reason why smaller, non-power tilt engines use a reverse lock, but there is no lock when in fwd (which also allows the engine to kick up upon a strike, of course). Something's not making sense there if that is, indeed, what is happening.

It totally sounds like air in the system. If you tilt the engine up, does stay up indefinitely or does it eventually start to lower on it's own?

[Bulls-eye]

Yes. The force of the prop (in fwd gear) far exceeds the pressure of the water against the gearcase as the boat is moving. Same reason why smaller, non-power tilt engines use a reverse lock, but there is no lock when in fwd (which also allows the engine to kick up upon a strike, of course). Something's not making sense there if that is, indeed, what is happening.

It totally sounds like air in the system. If you tilt the engine up, does stay up indefinitely or does it eventually start to lower on it's own?

Thanks

Motor stays in the upright position if I leave it up and does not appear to bleed down. Leaving the acceleration question aside, I do not believe the tilt ram should be able to move in an upwards direction ( maybe an inch but not indefinitely) . The motors are twins the port motor i can literally lift up and watch the tilt ram moving upwards ( it takes some force but done by hand) the starboard motor tilt ram does not move under this same lifting by hand. I’ve tried it on other motors and they don’t allow it either. So, I’m thinking either air or some type of bad valve or something. I just don’t have enough knowledge how the system moves it’s fluid to determine what specifically it might be.


Regards..

[DennisG01]

You're correct - you should not be able to lift it. Manually lifting it is basically the same as putting it in reverse.