Knocking when turning

LReed27

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Aug 4, 2025
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Attached is a video I took of our boat on the water. We recently replaced the bellows, gimbal bearing, and the shift cable. We used the alignment tool when getting the gimbal bearing back in. In the process we inspected the u-joints which looked good and had no play. The reason we did all the work was because of a leak in the shift cable bellow. Besides that, the boat ran and sounded good. Recently we noticed that the boat was making this knocking sound. We figured it was maybe the u-joints but we looked at them again and there didn’t seem to be an issue with them. Once it was put together, we took it out and it still did it. The knocking occurs when the boat is turned all the way in either direction. It’s hard to tell but it sounds like it could be coming from the back of the motor by where the steering actuator is. It sounds faster when the boat is turned to the right and slower to the left. Is there a chance it’s something to do with the power steering or is it more likely to be the u-joints? I would prefer not to take the lower unit off again if not needed. Next chance I get I was thinking about taking the belt off and trying to run the boat for a tiny bit to see if the noise goes away. Any ideas would be appreciated.
 

alldodge

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Welcome
The knocking occurs when the boat is turned all the way in either direction
Most likely it is the U joints
With motor in neutral and turn full either direction, does it still knock?
 

Bondo

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We figured it was maybe the u-joints but we looked at them again and there didn’t seem to be an issue with them.
Ayuh,...... Welcome Aboard,...... I think it's the u-joints too,......
I've seen u-joints that felt perfect, 'n tight, but were bad,.....
The cross-bearings, inside the caps get little tiny ridges on 'em, 'n cause the problem,......
 

LReed27

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Ayuh,...... Welcome Aboard,...... I think it's the u-joints too,......
I've seen u-joints that felt perfect, 'n tight, but were bad,.....
The cross-bearings, inside the caps get little tiny ridges on 'em, 'n cause the problem,......
I’m thinking u joints but hoping for something easier 😂
 

LReed27

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Ayuh,...... Welcome Aboard,...... I think it's the u-joints too,......
I've seen u-joints that felt perfect, 'n tight, but were bad,.....
The cross-bearings, inside the caps get little tiny ridges on 'em, 'n cause the problem,......
Would that be something that could be tightened or something or would I need to replace them? I’ve seen things about using clamps to get the caps tighter or something.
 

Bt Doctur

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Aug 29, 2004
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not fully n seating the gimbal will make the same sound even with new U joints

Can you elaborate this
We used the alignment tool when getting the gimbal bearing back in.
 

LReed27

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not fully n seating the gimbal will make the same sound even with new U joints

Can you elaborate this
We used the alignment tool when getting the gimbal bearing back in.
Yeah we measured where the old one was and then drilled the hole to line up with that. Then with it lined up, we used that to hit the new one in
 

Scott06

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Yeah we measured where the old one was and then drilled the hole to line up with that. Then with it lined up, we used that to hit the new one in
pull the drive see if the gimbal is fully seated, if not seated drive it in more. if seated replace u joints. my ujoints felt fine but when I changed them you could see wear on the crosses

What drive do you have ? generally you can get a ujoint from an auto parts store vs paying the ridiculous price of oem merc ujoints
 

LReed27

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pull the drive see if the gimbal is fully seated, if not seated drive it in more. if seated replace u joints. my ujoints felt fine but when I changed them you could see wear on the crosses

What drive do you have ? generally you can get a ujoint from an auto parts store vs paying the ridiculous price of oem merc ujoints
So we took the outdrive back off and found that we were able to get the bearing in more. And we checked alignment after and the tool goes in nicely with even spline marks. But we go to put the drive back on and we can’t even get the drive to the studs. It’s an alpha one gen 2. We have the drive selector in forward and the outdrive in the forward position. We’ve tried spinning the prop. The cable is going in where it should. But it’s still catching something and we’re at a loss again. Any ideas?
 

alldodge

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New gimbal bearings are stiff. Put alignment bar in and make sure it goes all the way in. Smack the bar hard with your hands, up/down/left/right a few times.
 

Scott06

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Only other thing I could think is the orings on driveshaft are getting hub=ng up on gimbal bearing or not greased well. I had a hell of a time one time when I forgot to grease the orings.

Also when turning the prop was it locked in gear CCW? otherwise it will pop out of gear and you think you are turning the driveshaft but actually are not... when I put the drive in I hold the prop CCW with a bungee to keep it locked in gear.

Also sometimes a good nudge is needed especially if the coupler is full of grease from adjusting alignment
 

LReed27

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Only other thing I could think is the orings on driveshaft are getting hub=ng up on gimbal bearing or not greased well. I had a hell of a time one time when I forgot to grease the orings.

Also when turning the prop was it locked in gear CCW? otherwise it will pop out of gear and you think you are turning the driveshaft but actually are not... when I put the drive in I hold the prop CCW with a bungee to keep it locked in gear.

Also sometimes a good nudge is needed especially if the coupler is full of grease from adjusting alignment
I’m not actually sure if we had our orings greased enough, I’ll pay more attention to those when we try tonight. We have been making sure the prop locks ccw. We learned that one early lol.
 

LReed27

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Very light grease on the O'rings on the shaft, too much and it will fight you.
We have done very light grease and it is still not going in. It feels like it’s hitting something metal but the splines look fine and we have spun the prop. I don’t know what else we could try to get this in. We’ve tried everything else I’ve seen like moving the inside of the bearing and checking alignment using the tool. It slides in easy. But the lower unit will not go on
 

Scott06

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We have done very light grease and it is still not going in. It feels like it’s hitting something metal but the splines look fine and we have spun the prop. I don’t know what else we could try to get this in. We’ve tried everything else I’ve seen like moving the inside of the bearing and checking alignment using the tool. It slides in easy. But the lower unit will not go on
I wonder if the driveshaft , u joints and inout shaft snout of the drive are getting hung up in bellhousing.might try a different angle to the drive are/ bellhousing raise or lower trailer front ?
 

jimmbo

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Put Grease only on the Splines. Grease on the end of the Shaft could prevent the Shaft from full Insertion
 
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