OB tilts up in COOL temps, but not in HOT temps ... ??

[DaleH]

Wow, new one on me! 40hp Yamaha with power tilt (no power trim rams).

ISSUE:
Works great in temps to 85-degrees (or best I can judge) but once warmer/hotter weather sets in, the motor still cycles but the OB doesn't tilt. In the mornings, she'll tilt all the way up fine. But once I get home in the afternoons, she'll move 6" or so and stop, though the pump is still activating.

TESTS:
* One morning I did cycle it up and down 3-4 times (resting the motor between lifts) to remove any air, as these t/t units are self-bleeding. All appears well there.
* Yes, I checked, but the oil fill level is right up to the hole, per the OEM Factory Service Manual I have on hand..
* The Manual release valve is tight.

THEORY:
All I can imagine that is happening is that some 'seal' gets weak in the warmer temps and allows the oil to enter the bypass valve and cycle 'around the tilt ram' instead of pushing it up. FWIW I have already backed off the tilt-tube nuts that hold that tilt-tube in place, and all is lubricated, plus easy to move.

Anyone ever hear of anything similar? I did order replacement O-Rings for the manual release valve already, but I'm wondering whether I shudda got them for any internal seal ...

Uhhhhhhhhhhhhh yes, my new OB is a Yummie !

 

[Porkchunker]

Sounds like a short in the wiring...when cool and shrunk, you have contact, when hot and expanded, you have a break.

Dave

aka

 

[DaleH]

Sounds like a short in the wiring ...

Nope ... tilt motor always works and sounds strong morning and night. I might replace the manual relief valve and flush the system, maybe someone else put the wrong trim/tilt oil in there ...