craig newton
Seaman
- Joined
- Jul 23, 2019
- Messages
- 58
96 Mercruiser 4.3lx 6cyl vortec with alpha one gen two outdrive.
I took the outdrive off and installed a new water pump kit. Who ever did it last broke two of the four housing bolts off and left it like that. I drilled them out and mounted the new housing with 4 new bolts. Didn't see any other damage so I re-installed the outdrive and with the muffs on water was circulating fine. It started and idled fine. I launched it for the first time today. Getting under way and got up on plane started out fine but then a loud vibration and shaking started so I shut it down. Ended up limping back to the dock at barely over idle speed. Still vibrating and still loud. I couldn't tell where it was coming from. I checked the prop and found it had about half inch of play in it. It was firmly attached to the shaft so pulling on it moved the shaft in and out about half inch. Is that normal? What is the most common reason for a loud vibration like that? How would you go about finding the source?
Some additional information:
The first time I drained the oil I did so with the cap from the reservoir in the engine compartment removed. It was less than half full to begin with. The amount of oil drained was just over half a quart total. It wasn't dis-colored and no metal was present in the pan or on the magnetic screw.I removed the lower half only to change the impeller. Found no damage to the shaft or spline. Only the two bolts that were broke off in the housing which I repaired.I had trouble getting the lower back in by myself so I set it on a stand and removed the upper half.and got it bolted together. No damage to the splines or the shaft and the u-joints movement was fine. There was a small pool of gear oil in the main bellows (maybe 3 tbls) along with the small pieces of rust colored metal shown in the picture. There was no sign of water and the smaller bellows below were dry and clean. I cleaned the main bellows and used a scope to inspect the bellows and the gear the shaft goes into. Didn't see anything broken or torn so I rented a crane and put it back together., launched it, got up on plane and forced to shut it down and idle back to the dock due to the loud vibration and rough running.At no wake speed it was louder than usual but very little vibration.
I took the outdrive off and installed a new water pump kit. Who ever did it last broke two of the four housing bolts off and left it like that. I drilled them out and mounted the new housing with 4 new bolts. Didn't see any other damage so I re-installed the outdrive and with the muffs on water was circulating fine. It started and idled fine. I launched it for the first time today. Getting under way and got up on plane started out fine but then a loud vibration and shaking started so I shut it down. Ended up limping back to the dock at barely over idle speed. Still vibrating and still loud. I couldn't tell where it was coming from. I checked the prop and found it had about half inch of play in it. It was firmly attached to the shaft so pulling on it moved the shaft in and out about half inch. Is that normal? What is the most common reason for a loud vibration like that? How would you go about finding the source?
Some additional information:
The first time I drained the oil I did so with the cap from the reservoir in the engine compartment removed. It was less than half full to begin with. The amount of oil drained was just over half a quart total. It wasn't dis-colored and no metal was present in the pan or on the magnetic screw.I removed the lower half only to change the impeller. Found no damage to the shaft or spline. Only the two bolts that were broke off in the housing which I repaired.I had trouble getting the lower back in by myself so I set it on a stand and removed the upper half.and got it bolted together. No damage to the splines or the shaft and the u-joints movement was fine. There was a small pool of gear oil in the main bellows (maybe 3 tbls) along with the small pieces of rust colored metal shown in the picture. There was no sign of water and the smaller bellows below were dry and clean. I cleaned the main bellows and used a scope to inspect the bellows and the gear the shaft goes into. Didn't see anything broken or torn so I rented a crane and put it back together., launched it, got up on plane and forced to shut it down and idle back to the dock due to the loud vibration and rough running.At no wake speed it was louder than usual but very little vibration.
