Just finished lower unit rebuild - weird noise!!!

[RudeRunner]

Hello all,<br /><br />I just finished rebuild the lower unit on my 1980 Evinrude 9.9. I replaced the water pump impeller and housing, all driveshaft seals and bearings, new o-rings, gear oil, etc. I lake-tested it today. It runs great and pumps plenty of water. The only thing is a weird noise when it's in neutral. It sounds like meshing gears. It is not a whine, grind, or squeal. The only way I know to describe it is it sounds like some car's power steering when you turn the wheel all the way to one side or the other. Kind of a humming sound. It goes completely away when I put it in forward or reverse. Is it maybe just the new water pump I hear turning? It goes into gear very smoothly with no clunking or grinding. I hope I didn't screw something up. I did not remove any of the gears, shift linkage, etc. when I dropped the lower unit.

 

[tiller7104]

Re: Just finished lower unit rebuild - weird noise!!!

Take it back apart......9 people could give you 9 different remedies. Break it down again and look for odd wear spots, silver flecks in your gear oil etc, if you rebuilt the lower end yourself I am not telling you anything that you don't know. I know it is hard to bring yourself to do it again. Play it safe, it is not worth gernadeing your lower end! Just a thought!!!

 

[ob]

Re: Just finished lower unit rebuild - weird noise!!!

My guess is that the shift linkage is slightly out of adjustment and what your hearing is slight engagement contact.Just a guess.Does the prop seem to spin when it's running in neutral?Many will, due to oil squeeze but if enough out of adjustment,they will spin excessively due too closer oil squeeze or light mechanical contact.Otherwise,something else is amiss.

 

[G DANE]

Re: Just finished lower unit rebuild - weird noise!!!

This made me remember an old post from a guy that replaced his water pump and had a strange whining sound afterwards. Turned out to be a piece of the old rubber o-ring around top of drive shaft that found its way up in the hole in the cranckshaft and pressed the driveshaft down, making gears run tight. If you loosen the bolts and allow the lower unit to drop 1/8 " or so you will know if something reduces your end play. Schematic helped him out on that one.