Tilt Trim - Yamaha C60 - Motor "leaks" down

I have noticed over the past several years that my motor (Yamaha C60 (99-00 vintage) Remote Steer) will "leak down" and you have to hold the up tilt button for quite a while before it will actually move the motor up. Usually this is only an issue if the boat has been unused for a while (I do use a lower unit brace when trailering and storing) but here lately I have also noticed that when running on plane I have to continually "bump" the trim button to keep the motor raised up as far as I would like. It is "leaking down" when on plane.

My question is, is the piston rebuildable in the T/T unit? I have to think I have a seal or O-ring(s) that the fluid is going past in order for it not to hold pressure. I have attempted to add fluid and bleed air in the past only to find that I cannot add more fluid. So seals/o-rings is what I am thinking have gone bad. I have attempted to attach a diagram of the unit. I really do not want to spend $500+ to buy the whole piston sub assembly (20) and would rather replace whatever the wear items (18, 19, 21-26) that will help stop the loss of pressure that leads to the motor falling down. POWER TRIM TILT ASSEMBLY - 1999 Yamaha Outboard 60hp C60TLRX | Crowley Marine

Attachment 373856

Thanks in advance.

Or after watching a youtube video I suppose it could be parts related to the trim cylinders? I guess if I am taking the time to tear into it it is a good idea to replace the seals/o-rings on the tilt piston and the trim cylinder pistons as well?

If you are not very mechanically I would not attempt this. There are a few guys on here that you can mail it to and they will fix it. There are shops that can fix it for you. It is expensive. If you can find a rebuilt one on eBay with a guarantee might be an option. Other than that best option is add on bracket.

Before you start all this have you tried adding fluid with an o-ring additive bleeding the air and running it a bit.

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If you are mechanically inclined and have some good tools I’d get a complete seal kit and completely rebuild it. Looks complicated but not as bad as it looks in the diagram. cleanliness is key when working with hydraulics. And if it has a couple of Teflon washers in it they can be tricky to install. They are best soaked in hot water for a bit to let them stretch then as they cool they will shrink back to size.

Pretty mechanically inclined. Just don't have a pin wrench the correct size for the caps. Will probably make one.

After watching the service tech vid on the trim cylinders it is a piece of cake. He did not however mess with the tilt cylinder. it looks more involved just due to where it is located and harder to get to. I think I will replace all seals and rings on the trim cylinders and see how it performs.

Have you checked the emergency relief valve? Sometime they work loose.