Thread: Another Yamaha V-6 Trim & Tilt Rebuild

Removing the motor with a long metric Allen wrench exposes the pump intake filter. I like to completely drain these units to clean out the residue accumulated at the bottom of each cylinder.


Once the unit has been inverted long enough for all the fluids to drain I disconnect the bottom hydraulic line to the Tilt cylinder and using compressed air I push the very bottom piston cup out of the cylinder. It's good to have a thick layer of rags over the cylinder opening catching the piston cup when it pops out.



Afterwards I crumple up paper shop towels and using a long flat bladed screwdriver rotate the paper towel both ways till I wipe all the debris out of the bottom of all the cylinders. A brief shot of compressed air is used to flush out any paper fibers that may be left inside helps prevent paper contamination.



This screwdriver has a 14in flat blade, catches the paper easily.



I like to do the Caps first, using a pick I remove the o-rings and backer rings if resealing the original caps. Older caps will have a snap ring to remove first retaining the wiper seal. Here I am using new caps, when I see 3 new caps on a T&T unit I know I replaced every seal, o-ring, & backer ring in the unit. I do save the old caps because in a emergency I can throw a Trim cap on standing in my flatboat when the boat I'm working on is still in the lift. I always lubricate the bodies very well with T&T Fluid before installing the o-rings & backer rings.




Resealing the Trim pistons themselves I follow the same careful practice. Once all the parts have been replaced I lubricate the cylinder very well with T&T fluid then install the piston all the way to the bottom of the cylinder. I used to fill the cylinders up with fluid leaving a air space but that makes it harder to bleed all the air out later. I lubricate the piston rod and slide the new cap on and thread it down almost to the cap's o-ring seal before doing the other side. Once both sides are on I screw both caps all the way down.



Breaking the Tilt cylinder is a bit more work. You must remove the Torx screw on the bottom first and remove all five springs with the checks on the bottoms, the small balls too not loosing any then place the Piston Ram Eye in a vice to hold it securely while you remove the Head. I have thick saddle leather in the vice jaws protecting the Eye.



I use a large spanner for rebuilding hydraulic cylinders to remove the head. I choose the correct pin size for the holes so I don't damage the head then insert the pins fully before applying pressure to remove the head from the stem threads. The threads have Loc-Tite on them so there is resistance when breaking the head loose.



Once the old cap is removed I install the new seals on the replacement Tilt cap carefully placing the backer ring in first from the top then turning the cap over to install the o-ring from the bottom while my pinky finger keeps the o-ring from missing its grove and position below the backer ring. I tool I have for removing stuck caps destroys the stuck caps in the removal process.



Wash all the oil off the stem threads and out of the bottom piston first then dry completely before soaking the stem threads with Loc-Tite. At this point the Tilt Ram can be assembled. Be sure and slide the new cap on the stem before you add the thread locker to the threads. Using the same spanner wrench I install the head to the stem.



After the Tilt Ram is completely assembled I install it all the way into the cylinder body, thread down the cap, and reattach the hydraulic line to the bottom. Doing the reassembly this way reduces the trapped air in the unit.



The cleaned sealing surface of the fluid reservoir gets a new o-ring then installed onto the unit. I fill this side with fluid up to the fill hole the move over to the motor side.



I fill the motor side with fluid and take a break. Air will bubble up slowly for a while, I let it purge itself and do something else. Afterwards I install the motor and using a spare battery place the BLUE motor lead to the POSITIVE POST on the battery and the GREEN motor lead to the NEGATIVE POST on the battery with my hands. I always attach the positive side first. This will start the pump in the right direction to begin with and start filling the Trim cylinders from the bottom. You must keep the reservoir from running dry at the same time so I keep topping it off till the Trim & Tilt cylinders are fully extended.



Once they are fully extended I open the release screw on the side then by hand push the Tilt cylinder down first then both Trim cylinders at the same time.



You keep doing this till you work most of the air out. The reservoir will need to be topped up each time you complete a cycle. Now the unit is ready to be installed in the engine.