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Last time out on my old boat I leaked gear oil into the bilge (I got a new boat, but may use the old drive and motor. see here for details: http://forum.chaparralboats.com/index.php?showtopic=26634). Also, the gear oil was milky and had water in it. I had just replaced the impeller and all of the surrounding gaskets. I had also just changed the gear oil and it had metal shards in it before servicing, and also after my last time out. So, what could be my issue? I think it may be the o-ring in between the upper and lower casing. Also, maybe it was a missing gasket on the oil plugs (not sure, I will check next time I see the drive)? What else could it be? All of the gears, splines, u-joints, yoke, etc. looked very good and were not work. I have no idea where the shards could be coming from.



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For an Alpha 1 Gen II, the more common areas that water can enter the unit is through the following:

Missing, damaged, or doubled up drain screw washers - take a small flat screwdriver to get down to the aluminum surface when removing

Prop shaft seals - often fish line lifts the seals

Shift shaft bushing seals -

There are other areas that can leak, but they usually have gear oil leaking out.

Carrier seal under the impeller

Yoke seal

Surprisingly I've personally never run across a missing o-ring for the oil passage way where the upper and lower cases meet together. I would think oil would leak out, especially when running, but maybe water would get in too.

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Gear oil in the bilge:

  • +1 on the yoke seal (would require not having a gimbal bearing oil seal / missing or damaged drive shaft o-rings)
  • Drive lube monitoring reservoir /hose

Was the drive pressure tested after the impeller replacement?

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Thanks guys! The gear oil may have been leaking out of the reservoir. I will check and see. As for the yoke seal: All my bellows and O-rings were in great shape after I removed the drive from what I could tell. I will look at all the seals you guys mentioned!

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