F100: replacing the hydraulic tilt oil

[jack daniels marine]

Hi folks.
My F100 is 9 years old and has probably still contains the original tilt oil, so I want to replace it completely while the boat is on a trailer. This motor has just 1 piston.

Is suction the only way to get the old oil out? in which case will this sequence work ok?:

1. suck ( with motor up )
2. refill
3. tilt up/down to mix the old and new oil
4. repeat until the oil sucked out looks ok.

or will lowering the motor with the fill plug removed expell oil ?

 

[boscoe99]

Re: F100: replacing the hydraulic tilt oil

Lowering the motor with the fill cap removed will generally blow oil out.

Without removing the entire assembly, then the piston from the cylinder, and turning the assembly upside down, I don't see how you will get it emptied of old fluid. There is no Yamaha maintenance procedure that calls for the fluid to be replaced at any particular time.

 

[99yam40]

Re: F100: replacing the hydraulic tilt oil

unless you have had a leak it is a seal system and does not get contaminated , so I would leave it alone.
Never heard of anyone changing oil in T&T.
Sounds like changing the air in your auto tires because it is getting old

 

[Capt Ken]

Re: F100: replacing the hydraulic tilt oil

There is no procedure for changing the fluid short of disassembly.

 

[jack daniels marine]

Re: F100: replacing the hydraulic tilt oil

thanks for the tips guys.
I work a lot with hydraulics, but not on boats. If there is any contamination in there, small abrasive particles for example, these may increase the likelihood of a leak developing. 9 years is a long time for the same oil to be in use.
To avoid getting too much air mixed in the system, I think I'll just suck out what I can, refill, tilt up/down to mix it, and repeat. If the old sample looks ok under the microscope then I guess all is well.

If for example, I can suck out 1/4 of the system vol through the fill port. Then after 4 refills, it should be 94% new fluid.

Another question, The Yamaha F100 manual from 1999 specifies Dexron II. Is this still preferred? Or is a marine specific fluid better?

 

[boscoe99]

Re: F100: replacing the hydraulic tilt oil

Yes, the Yamaha specified fluid is Dexron II but I don't think that is available any longer. Dexron III is the latest specification. Or, you can use Yamaha branded trim and tilt fluid.

Given that small abrasive particles will be at the low points of areas within the system, how are you going to capture it all?

What you are doing can't hurt though. Might help. If you are familiar with hydraulics, however, why not just pull the unit, disassemble, clean, reassemble and then reinstall the unit? Not that difficult to do. Just keep tabs on all of the MSP contained within.

 

[jack daniels marine]

Re: F100: replacing the hydraulic tilt oil

the only way to get any sediment out of low points is to tilt and raise the motor a few times before I start the process to create some turbulance and mix it up a bit.
I dont want to disassemble the unit since it works just fine.

 

[99yam40]

Re: F100: replacing the hydraulic tilt oil

The T&T motor/pump on out boards runs very little time compared to the other hydraulic systems out in the world.
Just think about it, tilt down to start the day and a few bumps during the day and then the tilt up at the end of the day.
I would leave it alone unless there is a problem.

Most problems on T&T come from external rust or damage to the shafts not metal partials from inside the unit

 

[jack daniels marine]

Re: F100: replacing the hydraulic tilt oil

you are probably dead right 99yam40.
My unit especially, gets very little use. This 2005 engine has done about 400 hrs total.
I'll find out for sure if this is a waste of time or a good idea if I can get a fluid sample. I'll post the result, water or particle contamination.