Yamaha Tilt and Trim Hydraulic Piston Leak Diag and Repair

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Themis

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Hi all.

The tilt and trim on my Yamaha 70 is suspect. The switch gets it up out of the water no problem, and down as well. The issues is that there is a small leak I think from the piston. The engine slowly floats back to vertical if I don't brace it as well.

I have heard anecdotally that this is common on Yamahas, and not surprising on 15 year old ones.

Does anyone have this unit? I think it is the same Tilt and Trim as the Yamaha 115 2 stroke, as well as others? Where can I add hydraulic fluid? I did buy some leak-fixing liquid that I will try to use, as the repair at the marina supposedly runs north of $1500, which is lamost what the engine is worth.

Thanks
Sal
 
Could be from any of the O-Rings. But 1st check to see if the manual release valve is TIGHT. If that is loose, sure - she'll drop down. Usually it is 1/2-way down side of bracket that holds OB to transom, on SAME side as the trim motor. Use LARGE flat-blade screwdriver. May need impact wrench "carefully" if cannot be loosened by hand, or rap in on tool head with hammer. 'Righty-tighty' [closes] and 'Lefty-Loosy' [opens] it.

Also, most Yams have 'mooring locks' to lock all the way up. USE THEM and this won't ever happen, as otherwise stress on rams to go down puts pressure on system and components.

I would also NEVER use any leak stopper in a marine application, but you could be the 1st to try one!

Could also be a leaky or faulty O-Ring in a check or bypass valve.

I'd probably drain and flush the unit out well, use PowerTech marine tilt/steering fluid from Walmart, works as good as the brand name stuff and is actually made by one of them.

Best way to fill OB tilt/trims = http://classicparker.com/phpBB2/viewtopic.php?t=602
 
Dale,

Which is the fluid reservoir? I am attaching three pictures. Sorry for the silly questions. I am thinking the screw in the first photo is to access the reservoir, and the screw in photo2, on the side bracket, is a release valve?
 

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Yup, motor to left, remove that nut on column to right, that's the reservoir. That hole in 2nd photo is the tilt release, see the diagram depicted on it.
 
That trim/tilt assembly looks to be in pretty good shape for a motor of that vintage.
Good to see you here again. :wink:
 
Themis":1sv6sicf said:
Thanks Kevin! I am trying to run this engine as long as I can.
If you don't get 30-40+ years out of that V4 YOU did something wrong ...

I'm running an '85 Yam 40hp that looks mint and is sound on all fronts; compression, carbs, etc. , just needed a new trim motor recently. That's already almost 25-years old, but I figure with a waterpump service and t-stats every 3-years, a decarb every 50-hours, and having her propped right ... she should last a long time! Just had to upgrade the internal fuel lines due to ethanol as pre-early-90s lines were not alcohol SAE-rated.
 
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