1999 50 hp johnson 50pleea driveshaft spun

[1999 keylargo]

can anyone give me some advise please. after a great day on water headed to the landing cruising at about 3/4 throttle, I heard a noise like a misfire, got my attention, listened close, nothing engine running perfect, still at 3/4. about 30 seconds later it happened. boat slowed suddenly as if I pulled to neutral fast from 3/4,and rpms went up on power head. I quickly shut it down. ill skip story about getting towed in. got home hooked water to it started up , could hear grinding not good, no forward , no reverse and no water . dropped lower unit and found splines at top of drive shaft have spun in the power head where it splines up into the crank. I cant see the splines in power head, looking up through the hole. my question is do driveshaft's fail or wear out like this over time. are they softer metal than the crank shaft splines so it fails before damage is done to the crank splines or do I need to start looking for a crankshaft too. also is it possible to get drive shaft out of the lower unit without opening up prop shaft and removing gears etc. thanks james

 

[Bosunsmate]

Re: 1999 50 hp johnson 50pleea driveshaft spun

Poke your head up there and have a look with a torch, the driveshaft is often made of slightly softer material so you can get away with it, but other times it just seems to do both.
Did you hit something? have a look at the prop closely

 

[Bosunsmate]

Re: 1999 50 hp johnson 50pleea driveshaft spun

Looks like there is a nut on the bottom of the drive shaft so you will probably have to go the long way around and pull out the bearing carrier

 

[boobie]

Re: 1999 50 hp johnson 50pleea driveshaft spun

You'll have to tear down the G/C to replace the D/S. Then you'll have to tear the P/H down to replace the C/S. Or do what I did years ago. I put a new W/P in it and then cleaned up the D/S and the C/S splines. I got some Gray Marine Tex and put it on the D/S splines and the C/S splines and put the G/C back on the motor. Let it sit for 24 hrs and took it out and ran it. Two years later the customer came back and said it was still working.