Thread: Yamaha V-6's F250 4 Stroke Hydraulics Rebuild

I do these rebuilds for 5 years of service. They always go more but I expect 5 years with this level of service.



Complete new Hydraulic units for these 4 Strokes are $2650. For a $100 or so I can go thru them with OEM parts ( a little more if you have to buy caps) and make them work perfect for at least 5 years. You have to really clean them out.



So this piston was stuck in the cylinder, 150 psi air would not budge it but a grease gun will put up a ridiculous amount of pressure so that is what I used to pump the piston out. When it came loose it shot out due to the compressed air within.



It takes quite a bit of torque to overcome the threads and o-ring when breaking the trim caps loose. I always do it while the unit is still installed in the boat but here I'm building a Frankenstein. This clamp setup has not let me down yet. If and when I get a stuck cap I have a Air Chisel Tool specifically for removing stuck caps but it destroys the cap in the process.



These usually have light scratching like what is seen here. I polish them with Crocus cloth, wash them down, install new backer rings & o-rings, oil them up with fresh trim oil, and reinstall. They will pull out by hand if you wiggle the shafts while applying a light upward pull.



The dust seals in the trim caps just pop right out. I use a socket and extension to press back in place. The one picture it is hard to see but watery oil was under the dust seal, the piston o-ring was leaking by allowing the oil up to the dust seal. I set the caps back but do not worry about torquing till I install the unit.



This is the stuck Tilt Ram piston. I installed a new o-ring and set aside till needed. The o-ring that came off was super hard, I do not think it was a Yamaha part. Probably Aftermarket is my guess. The seals & wiper o-rings too.



Yeah, now we are getting to the nasty stuff. A long 3/8 Drive Allen makes removing the Motor & Reservoir easy. Usually the bolts let out a crack when breaking loose under the torque. Not much to see under the motor, that little motor to pump adapter only goes in one way so if it is flipped over the motor will not mate to the mounting surface. If you find the motor doesn't want to drop down swap the adapter around. I have a picture of it coming up. Look at all the junk & debris on the filter screen. I can't tell you how many failed units will have junk like this inside. The water in the oil corrodes the pot metal housings creating that junk out of thin air. It is very important to address a leaking seal immediately. If oil can leak out water is going in. All Bad!



I have the main housing upside down draining the water & oil out. Notice a small screwdriver blade is maintaining a crack so the oil has a place to run out.