25 Attachment(s)
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.
Attachment 483146
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.
Attachment 483147Attachment 483148
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.
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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.
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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.
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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.
Attachment 483165
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.
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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!
Attachment 483172
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.
20 Attachment(s)
Continuing Yamaha V-6 4 Stroke Hydraulics Rebuild
After the main hydraulic housing drained it is time to clean it out.
Attachment 483231
First thing is to clean very well the flanges that mate to the housing. The o-rings are so thin a very clean & smooth housing is necessary for a watertite seal.
Attachment 483232
This is the motor to pump adapter. The groves are not quite center, so make sure it is in the correct direction before installing the motor.
Attachment 483233
The insides of the reservoir and the bottom of the Tilt cylinder both has a oil/water sludge, I clean them out very well then wipe out as clean as it will get.
Attachment 483234Attachment 483235
I like to fill the reservoir with fresh fluid at this point along with the Tilt Cylinder tube leaving enough room for the Tilt piston mentioned earlier as well as the base rod components on the Tilt Ram Rod. I usually leave it like this overnight as air will bubble out if given time to work its way up. A new filter screen is added here too. A small brass adapter goes under the new filter screen, I didn't get a picture of it but its sticks thru the filter screen so you can't miss it.
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Before we can install the Ram Rod the Reservoir must be installed so here I clean the inside and out as well as the flange, install a new o-ring, and install the reservoir to the main housing using Nickel based Never-Seize.
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To replace the Seals in the Tilt Ram Cap you first must remove the valve assembly on the bottom of the shaft to allow the Cap to slide off. The Trim cylinders do not have fluid above the piston but the Ram does so a Wiper O-Ring and Backer Ring is installed in the cap as well as a Dust or Wiper Seal. A single Torx screw holds the Valve springs & Check Balls in place. Shims are under the spring retaining plate and must be return before installing the retaining plate.
Attachment 483242
Once you have the Torx screw, washer, springs, check balls (4 total here), & shims out of the way you can put the Eye of the Tilt Ram Rod in a vise to break the Valve Head from the rod. I use a spanner wrench for working on larger hydraulic cylinders for the task. As you can see I use a 1/2in drive to 3/4in drive adapter for this big spanner. I place the spanner pins in the holes where the springs were removed and it's standard right hand threads. Blue Loc-tite is used so it will take a bit of time to unscrew.
Attachment 483243Attachment 483244Attachment 483245
I use a seal pick to remove the o-ring & backer ring if reusing the old cap but here I'm installing a new one. The picture holding the cap is to show the orientation of the o-ring & backer ring. Again I use a socket & extension to press in by hand the outer wiper seal.
Attachment 483246
I use contact cleaner to remove any oil from the threads before adding the blue loc-tite and screwing together the sub-assemblies.
Attachment 483247
Here I'm replacing the lower o-ring and backer ring on the valve assembly piston. You can see the springs and balls on the paper towel.
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The balls go in first. One in each hole followed by the spring assemblies. The shims are added under the retaining washer, then the retaining washer, followed by the Torx screw washer & screw. Blue loc-tite is used on the screw too. Now you are ready to install the Ram Rod into the cylinder body.
Attachment 483252
I will cover bleeding in the next post.
4 Attachment(s)
Bleeding a Yamaha Trim & Tilt Hydraulic Unit on the Bench
It's important to bleed as much air out of your repair as you can so after re-installation the hydraulic unit will lift the engine thru the complete range of motion. Most hydraulic units have a release valve in the form of a screw on the side of the main body.
Attachment 483270
After closing the unit up and topping off the reservoir with fluid the release screw is opened to allow fluid to bypass as you push the Tilt & Trim Rams down by hand.
Attachment 483271Attachment 483273
Push down the Tilt Ram first. Once it is close to all the way down you will hear a air pocket being pushed out. Once the Tilt Ram is fully compressed I use a strap to hold it down while pushing both Trim Piston shafts down. One side usually goes down before the other, like the Tilt Ram when you get close to fully compressed you will hear air being pushed out. Now each time you push out air the volume of fluid in the Reservoir goes down. You always add fluid to the Reservoir with all the Rams fully extended. Close the Release Screw Valve at this point. Very Important!
Attachment 483272
You add fluid each time you run the Rams back out with a battery. I just use leather gloves to hold the wires to the battery terminals. When touching the battery terminals you must be forceful of a lot of arcing will occur. Its hard to see in the picture here but I have added fluid till the point its running out of the fill hole. At this point install the cap and repeat the bleeding process by loosening the Release Valve Screw, pressing the Rams down, tightening the Release Valve screw, raise the Rams with battery power until you hear very little air come out from under the cylinders. The bonus is this pushes air out of the pump itself to help it prime. After re-installation in the engine I usually have to use the engine weight a couple of times to compress the Rams for a final bleeding.
