Yamaha Showa 3 Piston Trim & Tilt

[Spunbearing]

I'm new here and stuck on a '97 yamaha 150 saltwater series. Having trouble with the trim and tilt, had a friend of mine helping me load the boat tilt the motor all the way up and was not able to tilt back down after that, pump motor would run both ways, so I checked the fluid and it was full. Pulled the unit out and put it on the bench and couldn't get it to go down, sounded like pump not building any pressure going down but had pressure going up. Tore the whole unit apart, pump itself, pistons out etc. Not able find anything like a stuck check valve or something along those lines. I reassembled the unit (quite fun) and cannot seem to get the air out of it. Have run out of ideas. Any ideas on why the piston stuck in the full up position in the first place and are there any tricks to getting the air out of the system. Thanks.

 

[rodbolt]

Re: Yamaha Showa 3 Piston Trim & Tilt

that showa unit is a pain,check the shuttle piston and the upper chamber main valve.
trick is to fill them as you reassemble it.
if you need the pump assy check with BRP, the fast strike uses the same basic showa unit and the complete pump asy is cheaper than the parts to fix one.
that system doesnt use fluid pressure to lower,it sucks the fluid from under the rams and it flows past the valve and into the cavity the retreating piston is leving.
thats why the cap only has a wiper seal and no sealing oring on the ram.

 

[Spunbearing]

Re: Yamaha Showa 3 Piston Trim & Tilt

Appreciate the help Rodbolt, I was looking at the parts breakdown of the pump assembly and it looks like the small check ball go on top of the shuttle pistons in the removable plate that forms the pump housing, when I took the pump apart, the little check balls were between the upper shuttle pistons and the lower check valves located in the bottom plate. Possible that somebody else had it apart and put it together wrong and that caused the motor to stick up. I was very carfull when I took it apart to make sure everything went back the same way. I have done work on valve bodies in automatic transmissions. It looks like the balls go in the plate first, then the shuttle pistons go in, tips up on both of them?