Augoose
Lieutenant Junior Grade
- Joined
- Mar 21, 2010
- Messages
- 1,245
I have an '89 4.3 with Alpha 1.
Recently I began experiencing severe vibrations and bumping sounds (like running aground) from the engine and lower unit when turning full left or right and while raising the lower unit at idle and not in gear. There was no slow onset of any odd sounds like growling or squeaking - just all of a sudden, deep bumping sounds and vibrations. Additionally, I can run the boat all day and not take on a drop of water in the bilge.
On an earlier thread, many folks suggested a failing gimbal bearing or u-joints can be the cause (much appreciation for the help), but before I headed back to the mercruiser shop to make my argument for warranty replacement (gimbal and bellows just replaced in April of this year), I wanted to educate myself a little further on what failed components cause what symptoms. At the time, the mercruiser shop told me they inspected the u-joints before replacing the bellows and that was all I heard about it. Also, I didn't want a poor explanation of the symptoms on my part on the thread lead to a misdiagnosis. If the u-joints were on the edge of failing back in April, I would have expected the shop to tell me about it so they could make more $ ?!?!? Right?
1) Initially I thought the u-joints only turned while the unit was in gear - but they turn whenever the engine is running correct? This would explain why I feel bumping and vibration while the engine is idling and the unit is in neutral? Could a failed u-joint cause a deep and aggressive bumping sound like that of the prop running into soft mud? When u-joints failed on my pickup truck it just creaked and groaned like crazy, but I experienced no horrible vibrations or bumping, so I'm questioning if that component could cause my symptoms.
2) I've read that when gimbal bearing begin to fail, people hear a grrrring sound or a squeaking sound from the transom area. As said, my gimbal bearing was just replaced less than 5 months ago and I've heard none of these sounds - rather all of a sudden, two days ago this bumping and vibration issue started. I've lifted the doghouse and watched the driveshaft spin as far into the transom as I could see during a time when I felt the vibration, and as far as my eye could tell, the driveshaft was spinning nice and balanced. Is it likely a 5 month old gimbal failed, and if so, could a failed gimbal cause such a bad vibration yet allow the driveshaft to spin so balanced? Also, the boat is not wet slipped - when not being used, it sits out of the water on a trailer.
3) Last question - could a failed coupler cause this issue or could something have caused the engine and lower unit alignment to change? I don't have any broken motor mounts that I can see and I haven't struck anything in the water that I know of. Also, the vibrations and bumping sounds are completely gone after speeding up beyond idle. I would think that if I have a broken motor mount or an alignment issue that the vibrations and bumping would only increase as I speed up or hit wake.
Sorry to be so long winded, I just have a lot of questions while trying to learn
Recently I began experiencing severe vibrations and bumping sounds (like running aground) from the engine and lower unit when turning full left or right and while raising the lower unit at idle and not in gear. There was no slow onset of any odd sounds like growling or squeaking - just all of a sudden, deep bumping sounds and vibrations. Additionally, I can run the boat all day and not take on a drop of water in the bilge.
On an earlier thread, many folks suggested a failing gimbal bearing or u-joints can be the cause (much appreciation for the help), but before I headed back to the mercruiser shop to make my argument for warranty replacement (gimbal and bellows just replaced in April of this year), I wanted to educate myself a little further on what failed components cause what symptoms. At the time, the mercruiser shop told me they inspected the u-joints before replacing the bellows and that was all I heard about it. Also, I didn't want a poor explanation of the symptoms on my part on the thread lead to a misdiagnosis. If the u-joints were on the edge of failing back in April, I would have expected the shop to tell me about it so they could make more $ ?!?!? Right?
1) Initially I thought the u-joints only turned while the unit was in gear - but they turn whenever the engine is running correct? This would explain why I feel bumping and vibration while the engine is idling and the unit is in neutral? Could a failed u-joint cause a deep and aggressive bumping sound like that of the prop running into soft mud? When u-joints failed on my pickup truck it just creaked and groaned like crazy, but I experienced no horrible vibrations or bumping, so I'm questioning if that component could cause my symptoms.
2) I've read that when gimbal bearing begin to fail, people hear a grrrring sound or a squeaking sound from the transom area. As said, my gimbal bearing was just replaced less than 5 months ago and I've heard none of these sounds - rather all of a sudden, two days ago this bumping and vibration issue started. I've lifted the doghouse and watched the driveshaft spin as far into the transom as I could see during a time when I felt the vibration, and as far as my eye could tell, the driveshaft was spinning nice and balanced. Is it likely a 5 month old gimbal failed, and if so, could a failed gimbal cause such a bad vibration yet allow the driveshaft to spin so balanced? Also, the boat is not wet slipped - when not being used, it sits out of the water on a trailer.
3) Last question - could a failed coupler cause this issue or could something have caused the engine and lower unit alignment to change? I don't have any broken motor mounts that I can see and I haven't struck anything in the water that I know of. Also, the vibrations and bumping sounds are completely gone after speeding up beyond idle. I would think that if I have a broken motor mount or an alignment issue that the vibrations and bumping would only increase as I speed up or hit wake.
Sorry to be so long winded, I just have a lot of questions while trying to learn