1993 mercruiser 4.3 alpha one noise

[ponchoman]

Got the boat running shifting great now. There is a noise when turning like a bad gimbal bearing but mine checked ok. I notice it way more pulling a tube. Could it be input shaft bearings? My u-joints were good too. It vibrates thru the hull. Thanks.

 

[Bondo]

Re: 1993 mercruiser 4.3 alpha one noise

Got the boat running shifting great now. There is a noise when turning like a bad gimbal bearing but mine checked ok. I notice it way more pulling a tube. Could it be input shaft bearings? My u-joints were good too. It vibrates thru the hull. Thanks.

Ayuh,.... Did ya take 'em apart, 'n check the cross bearin', or they just Feel Ok, no play,..??

that's where I'd look 1st,...

 

[ponchoman]

Re: 1993 mercruiser 4.3 alpha one noise

Shop didn't take them apart. They felt smooth. Noise increases with trim angles as well

 

[alldodge]

Re: 1993 mercruiser 4.3 alpha one noise

Shop didn't take them apart. They felt smooth. Noise increases with trim angles as well

As Bondo-o mentioned, u-joints

 

[ponchoman]

Re: 1993 mercruiser 4.3 alpha one noise

K thanks guys

 

[ponchoman]

Re: 1993 mercruiser 4.3 alpha one noise

So the shop takes my outdrive off. Upper drive seal was leaking into bellows. New stub shaft, seal etc... They disassembled ujoints and they were perfect. The gimbal was the next place to look. It seemed good, but they changed it while they were in there. Under load it could be a different story. test drive this weekend.

 

[sunsetter]

Re: 1993 mercruiser 4.3 alpha one noise

So the shop takes my outdrive off. Upper drive seal was leaking into bellows. New stub shaft, seal etc... They disassembled ujoints and they were perfect. The gimbal was the next place to look. It seemed good, but they changed it while they were in there. Under load it could be a different story. test drive this weekend.

That's what I have found with gimbal bearing as well, they can feel fine but put it under a load and it's knocking like crazy. If u can hear anything I change gimbal bearing first.

 

[ponchoman]

Re: 1993 mercruiser 4.3 alpha one noise

Thats good to know! Wow $2700 spent on this boat this year. Boat= bet on another three thousand! The previous 3 years saw nothing but fluid changes and a tune up.

 

[ponchoman]

Re: 1993 mercruiser 4.3 alpha one noise

Update... Its not the gimbal. Still got some noise/vibrations. Very noticable when pulling the tube. Boat started surging after, the rpms were contant but the boat was speeding up and slowing down. Kinda lost and ready to cut her loose.

 

[alldodge]

Re: 1993 mercruiser 4.3 alpha one noise

So the shop takes my outdrive off. Upper drive seal was leaking into bellows. New stub shaft, seal etc... They disassembled ujoints and they were perfect. The gimbal was the next place to look. It seemed good, but they changed it while they were in there. Under load it could be a different story. test drive this weekend.

They replace the upper seal due to a leak, took u-joints apart, but didn't disassemble the rest of the drive and inspect. Something just doesn't add up; a shops hourly rate will usually cost more to remove and inspect u-joints then to just replace. Do you think they just checked for play and that is done most ofte?.

Update... Its not the gimbal. Still got some noise/vibrations. Very noticable when pulling the tube. Boat started surging after, the rpms were contant but the boat was speeding up and slowing down. Kinda lost and ready to cut her loose.

If the RPM's are constant (maybe only slight variation) and the boat spead varies; about how much does it vary? Outdrive noise (maybe from no inspection) or prop loose?

 

[ponchoman]

Re: 1993 mercruiser 4.3 alpha one noise

They did look at upper gears. Slight wear but typical they said. Prop is possible its newer but the hub has seen some accidents. I would say it surges within 5 mph. The tube feels like its on an elastic band instead of a rope. My alternator belt needs changing it was slipping some. Dont know if that would cause that?

 

[alldodge]

Re: 1993 mercruiser 4.3 alpha one noise

If the rpm stays the same and you are changing 5mph when not pulling a tube, then it might be the prop hub. If the rpm stays the same while pulling the tube and in varies 5mph then no problem, the extra load is causing the issue. Alternator will not cause what your seeing.

If the engine is surging and rpm is changing it's either load or fuel depending on how much load is being added by tube.

 

[Volphin]

Re: 1993 mercruiser 4.3 alpha one noise

Given your comment of strikes with the prop, I'd be inclined to look at the prop and hub very VERY closely.

 

[ponchoman]

Re: 1993 mercruiser 4.3 alpha one noise

I did look at it seemed fine. I'm springing for a new hub prop jus to rule that out. Would u hear it slipping? Say a growl? Its not like the boat goes into neutral however.

 

[alldodge]

Re: 1993 mercruiser 4.3 alpha one noise

I did look at it seemed fine. I'm springing for a new hub prop jus to rule that out. Would u hear it slipping? Say a growl? Its not like the boat goes into neutral however.

You could hear a noise but most don't. With the drive down, engine off, put the throttle in reverse. Place a strap wrench around the prop and see if you can turn it clockwise. If the prop moves on the hub it is spun

 

[ponchoman]

Re: 1993 mercruiser 4.3 alpha one noise

Oops

 

[ponchoman]

Re: 1993 mercruiser 4.3 alpha one noise

Got a new hub today. Hopefully that takes care of that. Replaced the ujoints too. They looked ok inside no cuts or rust but its the last step to rid the boat o the vibrations. If its the coupler its going up for sale lol.