35 hp evinrude bearing lubrication

I have a 1976 35 hp evinrude. I started hearing a sqealing noise when throttling down or up sometimes but always when coming down off a plane. I'm worried it is a bearing sqealing. Now the parts manual shows the oil recirculation hose going from the lower crank bearing to the upper crank bearing, and the other going from the intake manifold to the upper cylinder. My service manual shows it going from the upper crank bearing to the intake manifold, and the other hose swapped as well. Does anybody know the right way to hook them up? I have it hooked up to where the upper and lower crank bearing are hooked together. This does not make sense to me just because i'm thinking about how the pressure would control the oil/gas mixture. To me it would be equal pressures back and forth and the oil would never really keep flowing through the bearings. If anyone could help me that would be great. thanks

Re: 35 hp evinrude bearing lubrication

Just a dumb question, what's your gear case oil look like ??

Re: 35 hp evinrude bearing lubrication

thats funny you mention it. I have been changing it out pretty frequently because it seems like there is a little water getting in it. It is turning darker after not much time. I changed the most rear seal too on the prop shaft. What is your thoughts?

Re: 35 hp evinrude bearing lubrication

An oil hose goes from the intake manifold to the upper cylinder bypass cover. That is a drain for fuel that has settled out of the airstream. It is sent to the cylinder for burning. Old motors simply dumped it in the lake.

An oil hose goes from the lower bearing to the upper bearing. Since gravity makes it settle in the lower area, it is piped up to the top to lubricate the upper bearing. I'm not 100% sure how that is caused to happen on that particular motor, but older ones had a drilled passage through the crankcase between the upper bearing and intake manifold, which applied manifold suction to the upper bearing.

Somehow, I doubt the squeal is caused by a bearing. It certainly wouldn't last very long if that were the case----like minutes. But on the other hand, I don't know what it is either. So, ???? I dunno. Your guess is as good as mine.

EDIT: Even if there is no manifold vacuum applied to the upper bearing, oil would still go up the hose. When the lower piston is on it's downstroke, there is pressure in the lower crankcase, and the upper piston is on it's upstroke, causing a vacuum in the upper crankcase. So the oil that is puddled in the lower case is squirted up through the hose, from a pressure area to a vacuum area. On the next 180 degrees of shaft rotation, the piston travel is reversed, and there is pressure in the upper crankcase, and vacuum in the lower case. Under this condition, AIR is blown back down through the hose. Big deal, it just isn't doing any good during this phase. The oil isn't simply cycling up and down because the pressure pulses last long enough to make it squirt out the top.

Re: 35 hp evinrude bearing lubrication

thanks for the info it really helped me out and understand what is going on inside the engine. If i figure out what the squeal is I will let yall know. Thanks again!

Re: 35 hp evinrude bearing lubrication

so i took the boat out today and i didn't tell you guys that i just put a new prop on it. the old prop was a 11x9 and it was chewed up and bent. I put a 10.5x11 prop on it wanting to bring down the rpm and get some more speed which it did. Well this is was is causing the noise. II took it off and put the old prop on and it stopped. Not sure why it is doing this maybe its too much torque but it only really does it when throttling down or just crusing around at low rpm, or maybe i just cant hear it at full throttle. any suggestions on that.