Hydraullic tilt piston wont retract?

[billko77]

I have just finished installing a new tilt and trim motor on my 94 johnson 100hp. I tapped the wires to my battery just to make sure the new motor worked before i put the whole T&T hydraulic system back on the boat. The piston went up no problem but now even with the vent screw open i cant get it to retract (which i have to do to reinstall it on the boat), either manually by pushing on it or by running the trim motor down. Any suggestions would be greatly appreciated. Thanks

 

[jonesg]

Re: Hydraullic tilt piston wont retract?

Read these replies by Joe Reeves, compressed air fixed it.
http://forums.iboats.com/showthread.php?t=381769

 

[tashasdaddy]

Re: Hydraullic tilt piston wont retract?

What you have done is over extended the tilt cylinder. mount the unit on to something stable. stick a pipe thru top mount of piston rod, now just slightly turn the rod, back and forth, with downward pressure. this is the reason for the limit switch.

then mount, and fill. Tilt motor all the way up and lock it there, open , fill, close. Unlock, lower motor all the way down. Now back up, lock, fill, close, lower. Repeat, repeat, repeat..

Use Dextrin II auto trans fluid, or power steering fluid.

 

[billko77]

Re: Hydraullic tilt piston wont retract?

Thanks for the insight. This my first trim motor swap and i hope this is what has happened. I will try it out in a couple hours and will post with my results.

 

[billko77]

Re: Hydraullic tilt piston wont retract?

I tried to work the piston down as you said and its simply not going to happen. I can get it down about a 1/4 inch and then as soon as i let go it returns to its original position on its own. the preesure does not seem to be relieved with the vent screw.It seems to me the system is still pressurized and has some air in it which would explain why it rebounds on its own. Im only compressing the air when i try to push it down-- i think. Excuse my ignorance but isnt the vent screw supposed to allow the system to bleed off? Thanks

 

[billko77]

Re: Hydraullic tilt piston wont retract?

OK, so i went back out and hooked the motor back up to the battery and applied as much force as i could manually and I got the piston to run down. I am now going to install and run the procedure Tashasdaddy recomended. I will post with the results. thanks

 

[Dhadley]

Re: Hydraullic tilt piston wont retract?

The system can go into a hydraulic lock. Basically equal pressure gets on both sides of one of the valves, probably the shuttle valve. Sometimes it'll naturally bleed off overnight but not always.

There is no reason the tilt ram shouldn't go all the way up and then retract if the system is working as it should. On some installations if the motor is tilted all the way up some parts on the front of the motor, like a hydraulic steering cylinder, may contact the transom or jackplate. The tilt limit switch is there so you can limit the travel to prevent damage to those components.

 

[billko77]

Re: Hydraullic tilt piston wont retract?

Thanks to all who replied, especially Tashasdaddy. Tilt is installed and filled with fluid and appears to be working excellent. I was a little worried last night but everything worked out great! Thanks again