JasonJ
Rear Admiral
- Joined
- Aug 20, 2001
- Messages
- 4,163
Day before yesterday, wife and I go out on boat for fun/sun. She is driving, we motor out of no wake zone, and she gives it full throttle to get on plane. Motor is screaming, we are slow to get on plane, float tube flies out back, she freaks out, we stop. Retrieve float tube, I drive, we head to favorite anchoring spot. Boat seems slow for rpms, I just attribute it to extra weight. Then the rpms start to fluctuate. We are cruising along at around 4500 rpms, and the rpms would climb to near 6000, then fall back. It did it repeatedly. I stopped, checked the prop for weeds, nothing. Again took off, it came up on plane just fine, and then would do the rpm climbing/falling thing again. It clearly wasn't a powerhead thing, as it sounded fine. It was acting like the load was changing. It was acting like the prop was cavitating or the hub was starting to spin. We got to our spot, did our thing, and returned, the problem still persisting.
This morning I decided to take it out to see if it would do it again. It was much worse. It got up on plane and was accelerating normally and then the rpms started to climb to the moon and the boat slowed and fell off plane. I reduced throttle to about 2500 rpms and the motor hummed along fine but the boat slowed to a near stop, then there was a dull thump and the rpms dropped. The boat came back up on plane and then the rpms started to climb and it fell back off plane. Okay I thought, prop hub is dying, I'll switch to the spare prop. It got even worse with the other prop on. It will cruise fine at displacement speed, there is no grinding sound or anything wierd soundwise coming from the motor. I have had lower units go on me before and I could tell those were a tragic gear event. This just feels like a huge slippage.
I am going to drop the lower unit and hand rotate the driveshaft to see if I can feel ruined gears, and check the splines on the shaft. My question is this: Is there any other soft joint in the drivetrain that could slip and fail like the hub of a propeller? Would this be located where the driveshaft couples to the powerhead or in the lower unit if such a coupler exists on this motor? I feel like there is none, but I want to make sure. The only other thing I feel it could be is stripped driveshaft splines, although the pee stream was powerful. If the splines were stripped it would have to be at the lower unit end or the water pump would not be pumping when the boat is near stopped and the motor is screaming. The other, more horrid possibility is the lower unit gears are roasted. I guess I won't know 'till I drop the lower unit. Any help is much appreciated.
This morning I decided to take it out to see if it would do it again. It was much worse. It got up on plane and was accelerating normally and then the rpms started to climb to the moon and the boat slowed and fell off plane. I reduced throttle to about 2500 rpms and the motor hummed along fine but the boat slowed to a near stop, then there was a dull thump and the rpms dropped. The boat came back up on plane and then the rpms started to climb and it fell back off plane. Okay I thought, prop hub is dying, I'll switch to the spare prop. It got even worse with the other prop on. It will cruise fine at displacement speed, there is no grinding sound or anything wierd soundwise coming from the motor. I have had lower units go on me before and I could tell those were a tragic gear event. This just feels like a huge slippage.
I am going to drop the lower unit and hand rotate the driveshaft to see if I can feel ruined gears, and check the splines on the shaft. My question is this: Is there any other soft joint in the drivetrain that could slip and fail like the hub of a propeller? Would this be located where the driveshaft couples to the powerhead or in the lower unit if such a coupler exists on this motor? I feel like there is none, but I want to make sure. The only other thing I feel it could be is stripped driveshaft splines, although the pee stream was powerful. If the splines were stripped it would have to be at the lower unit end or the water pump would not be pumping when the boat is near stopped and the motor is screaming. The other, more horrid possibility is the lower unit gears are roasted. I guess I won't know 'till I drop the lower unit. Any help is much appreciated.