Gearcase questions

[fishon1213]

Hello, I have a 1979? Evinrude 35hp. I believe I have a worn clutch and forward gear. The motor seams to slip/grind slightly under a heavy load, if I throttle down it pushes fine. I tried a different prop which produced the same result. I jammed the flywheel and couldn't spin the prop hub. It is a tiller and the shift lever seems to be adjusted correctly. This leads me to believe the problem is in the gearcase. Likely a clutch and gear.

I have the lower unit pulled off. All seals seem good. The gearcase oil was brown/black, no water. Do I take out the two bolts down behind the prop next to get to the gears?

Also, I have a 35hp Johnson parts motor that was given to me. I was told the lower unit is good. I was just going to swap the lower units but the way the shift linkage connects is different. They look exactly the same except the evinrude has the access plate towards the mid of the motor. The johnson has the access plate down close to the prop. So I am thinking the lower units couldn't simply be swapped. If the gears look good in the johnson maybe they could be swapped?

Thanks, AL

 

[wilde1j]

Re: Gearcase questions

You can't test for a spun hub using your method, unless you think you can generate 35HP +. Mark the inner and outer hubs with a indelible marker and run the motor under load until it "slips" ... if the marks have moved relative to each other, then it's a spun hub. Take the prop to a prop shop for rehubbing. A gearcase issue (clutch dog/fwd gear) feels like you hit a log every time ... there's no way for a gearcase issue to cause a smooth slip.

Does your motor have thru hub exhaust or is it from above the prop? If above, you may have a drive pin that's failed. In any case look at BRP Evinrude website fpr a parts breakdown.

 

[fishon1213]

Re: Gearcase questions

Thanks for the reply wilde. I have been researching online and looking at the motor alot today. It does feel like a relatively smooth slip, so hopefully I dont have a gearcase issue. I am going to test the prop like you said. The other thing I was thinking should have been my first stop which is possible cavitation. I used to run a smaller motor so it was never an issue. Do hydrofoils help with anticavitation? I'll have to experiment more with trim and weight distribution.

Both motors have thru hub exhaust. I am guessing the two lower units would not be interchangeable since the shift linkage is different. Would it be worth keeping for the internal parts?

 

[HighTrim]

Re: Gearcase questions

Go to the brp website and cross reference part numbers to see what applies.

Do you notice burns (erosion) on the surface of the blades at all? Is a usual side effect of cavitation.

Worked on a johnny once that the owner thought had a spun hub but the anti ventilation plate was snapped half off allowing surface air to be pulled into the blades.