Re: [OMC-Boats] Prop spinning in Nuetral?

Water hose was connected. Does it matter how much water is running through? I get a decent amount of water through my hose but not as much as where I used to live. The water is coming out the large hole that goes to the drive, a hole by the prop that has a screen and another hole a bit further up the drive. ________________________________ From: Ethan Brodsky <brodskye@...> To: Evinrude & Johnson Boats of the 1960's and 70's <omc-boats@...> Sent: Tuesday, August 11, 2009 3:29:31 PM Subject: Re: [OMC-Boats] Prop spinning in Nuetral? On Tue, 11 Aug 2009, Nexi wrote: > Took a next step to make sure the engine runs. Started her up with the > drive up, someone said this was ok as long as the boat is in nuetral. > Oddly enough the prop is spinning while in neutral. Shouldn't the prop be > at a stand still during neutral? With these drives, it's normal for props to spin a little bit in neutral. Even though the drive gears aren't engaged, they're still spinning on the shaft, so friction is enough to cause some prop rotation. To understand what's going on, think of a bevel gear on a vertical shaft coming down from the upper unit. The prop shaft is horizontal and has two bevel gears it that can rotate freely on the shaft - both are engaged to the vertical bevel gear, one on the "front" spinning "forward", and one on the "back"  spinning backwards.  This happens in forward, in neutral, and in reverse - all the gears are always spinning.  When you put the drive into gear, one of these gears is "engaged" by "locking" it on the prop shaft, so the prop begins spinning.  Thus, it is conceivably possible that the prop might turn forward, backwards, or not at all, in neutral, depending on which gear has the most friction with the prop shaft (probably which bearing is in the worst shape). The rotation might be fast, but there's no torque behind it.  Push a stick against the prop and you'll see that it stops immediately (I won't suggest using your foot, though that's what I always do).  Try this in gear and the stick will be broken or thrown out, or it'll break your drive (i.e. don't try it in gear).  In the water, viscosity and friction are usually enough to stop this from happening, though I have seen props spinning in neutral before. Also be sure you aren't running it *AT ALL* without a hose connected, as you will rapidly burn up the water pump if there is no water in the outdrive. Ethan -- Ethan Brodsky _______________________________________________ OMC-Boats mailing list OMC-Boats@... http://lists.ultimate.com/mailman/listinfo/omc-boats
Received on Tuesday, 11 August 2009