Lower unit problem. 115hp 81 evinrude

[fsujack21]

I have a 115hp 1981 Evinrude on a 20ft mako CC. I've had the motor about a year, I did all major maintenance (rebuilt carbs, replaced all fuel lines, head gaskets, thermostats, starter solenoid, etc) and aside from a few minor fuel delivery issues that some guys on here helped me diagnose she has been running great.

Today I was moving along at about 20kts about 500yds from my marina when my engine revved skyhigh and it slowed down immediately. I backed the throttle down shut off the engine, threw out an anchor an was expecting to see my prop missing or the hub to be spun. When I pulled the motor up the prop was still there. I tried engaging the throttle in gear and pushing the prop by hand and it would spin with only minor resistance. I lowered the motor again then pulled the cover off checked the linkage cable and seemed that the linkage was moving fine. I started her up again and I didn't have forward or reverse. I didn't make the definative "clunk" into gear in either direction. I got towed back in and had to leave her for the day.

I'll be bringing the trailer down to get her in a few days to pull off ther lower unit and see what's what but, before I do I was looking to get some idas on where to start looking. Aside from changing water pump/impellers over the years I have no other lower unit experience. Any sugestions on what to look for and how bad the damage might be?

Thanks
Jim

 

[emdsapmgr]

Re: Lower unit problem. 115hp 81 evinrude

Did you try another prop? Maybe the rubber thrust hub in the prop failed.

 

[fsujack21]

Re: Lower unit problem. 115hp 81 evinrude

Nope not yet Emd. I would be thrilled if you are right, I think you identified my last fuel delivery problem so, it would be great if your first huntch was on target again because that would be prob be the easiest fix. I kind of ruled out prop when I tried shifting again and there was no real "clunk" into either gear. But i"ll def give it a shot.

 

[5150abf]

Re: Lower unit problem. 115hp 81 evinrude

I would go with a broken drive shaft, the pinion or your clutch dog exploded, but something in the lower definately let go, I am on my 3rd lower an it is a terrible feeling.

Once you get it out drain the lower and I think you will have an answer to your question, look for metal chunks in the oil, both of mine let go at WOT in deep water, one was a pinion and the other was a forward gear, I think that prop strikes caused small cracks in the gears and under max load they finnaly let go.

If you don't how the lower works here goes, the pinion and gears are always turning if the engine is running, the clutch dog slides back and forth on the prop shaft and engages the gears so if any of those break the engine won't turn the prop.

I really really doubt it is a spun hub, the prop would almost have to be falling off to slip turning it by hand.

 

[fsujack21]

Re: Lower unit problem. 115hp 81 evinrude

It was a broken drive shaft. Had serious water intrusion in lower unit oil but no visible metal. After fighing with the shift rod screw under the carb i dropped the lower unit and when I took the water pump off the drive shaft came right along with it. It sheered off right at the base plate. Looks like the grommet on top of the water pump failed and corroded everything. I found a used lower unit on craigslist that fit for $125, I slapped her back on and she worked just fine with muffs. Gonna take it for a sea trial in the am. Thanks for the input

 

[coolguy147]

Re: Lower unit problem. 115hp 81 evinrude

check the oil on the lower unit