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Powertrim Issue

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Werner1976

New member
Hi there, last year I bought a speedboat with a yamaha 90 hp from 1988. A 2 stroke 3 cylinder. The first problem that came up, is that the engine lowers at a slow speed when the power trim is fully trimmed up. I have already replaced all seals on both rods and also on the middle cylinder. However problem remains. I also replaced the seals at the manually lowering / lifting screw. The oil that i use is dexron 2. Anyone an idea?
(Sorry for my bad English)
 
It maybe internally leaking. Unless you an find a hydraulic place or a good marine shop to repair it. May just as well get another used or new one. These trim pumps can be costly to fix.
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The PTT unit is sealed thus essentially pressurized. If the unit lowers w/o you activating the switch, this indicates loss of pressure, which indicates a leak. Just fyi, it’s nearly impossible to determine which of the seals is compromised. So all of the seals are replaced and done so in a sterile-like environment. I’d refer to your service manual procedure for pressurizing the unit. Once complete, tilt the engine up half way. Check back a few hours later or next day. If engine has tilted down, you’ve confirmed a leak.
 
Problem solved. With tilt function the engine trimmed all the way up. Then blocked with the support clamp. Lower the trim rods completely with the tilt switch. Open the manual release valve, unlocked support clamp , and lower the motor on its own weight. Did this twice and the engine now stays up.
 
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