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Lower Unit Issues - Optimax 115

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  • Lower Unit Issues - Optimax 115

    I put the boat up in the fall with no apparent problems. Took it out for a shakedown run, water pressure good, cooling fine, after some medium throttle for a few minutes and confirmed it was cooling right I pushed it on up to near wide open throttle, pulling back a little for the conditions. After a few minutes of this it felt like I lost thrust and it sounded like the engine RPMs shot up a little.

    I immediately pulled the throttle back and there was a noticeable rattle, similar to the sound it makes when going into gear.

    I was still able to get it into and out of forward and reverse and the rattle matched engine rpms. We limped home 30-45 minutes at around 1000-1200 rpm. The rattle is there even when it isn't in forward or reverse. When I took the lower unit off and ran the engine the rattle was gone.

    Lower unit oil wasn't cloudy but there were probably 20-30 salt grain sized metal bits in it.

    When I try to turn the driveshaft by hand, the prop shaft will move unless I put a little pressure on it and it won't. The driveshaft hits a snag and I can't by hand turn it past this snag. If I spin the driveshaft backwards it hits a snag at the same spot. Is there any other diagnostic type stuff I can do without really digging into the insides of the LU? I'm trying to decide whether to bother with getting a shop to look at it in the middle of the summer or go with an SEI unit.

  • #2
    Probably a bearing seized up. If there was any water in gearcase when put it in storage then bearings can rust and seize or if have a small oil leak then oil level will be too low and cause bearing damage. It would need to be disassemble to see if can be rebuilt.
    Regards
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