Outdrive initially jammed when turned by hand

[BenchmarkMarine]

I didn't see my exact outdrive symptoms when searching past threads, so I'm posting this for advice on next steps.

I have a 1996 Alpha One Gen 2 outdrive. While towing a tube on the lake, a few hours into our day, we heard a bang, lost drive suddenly, had a bad smell of burning rubber, plus smoke coming from coupler end of engine. The coupler had been replaced when we did the engine rebuild over the winter, but it wasn't an OEM Mercruiser coupler. I expected from this that the cheap coupler had failed and that was my first problem, but that's not why I’m posting this question.

• My concern is that after removing the outdrive I could not turn the yoke by hand at first. After multiple tries I was able to get it moving after feeling like it was slowly freeing up. No noises. I could not find any cause for why it wasn’t turning at first. I could not recreate the problem when turning by hand.

Questions:

• Should I be worried about it initially being bound up even though the outdrive eventually now finally turns OK by hand?
• Are there some things I can check to narrow down if there is an issue with the lower unit? I know how to remove the gearsets in the upper as I've done it before, but I've never tackled the lower unit. See below for what I’ve checked so far.

Longer explanation:
To get started on the coupler replacement, I removed the outdrive from the boat. Before progressing to the Coupler which I’m sure is ruined, I tried spinning the yoke shaft on the outdrive by hand to make sure that turned without issue. Problem is, I couldn’t turn it in either direction no matter if the shift shaft was placed in forward or reverse direction. If I reached around to the prop it spun easily in either direction, which also seemed weird. After trying a few more times and turned the yoke as hard as I could, it seemed to slowly free up and then start turning normally by hand. I can’t figure out what caused it to bind up at first, so looking for advise as to whether this could be expected from having pulled the outdrive, or if I’m facing an intermittent problem? I could not recreate this issue once I got it moving the first time.

BTW:

• I removed the top cap and saw nothing wrong with the gear oil. No bad smells either.
• Gear oil level was aligned with the top of the upper plug.
• I have drained the gear oil to check for any metal bits – gear oil looked clean and free of debris
• There is a bearing at the very top (the one with the cup installed in the top cover) which seemed to have some wiggle by hand, but this doesn’t seem to be so bad as to jam things up.
• I had changed all seals in the upper unit this past winter. Bearings all felt good at that time. I did not touch the lower unit bearings.

Additional finicky behavior?
This may be unrelated to the above, but to get the prop to turn with the yoke, I found that if I manually turned the yoke a bit more aggressively while the shift shaft was set for forward it would engage the cog and so felt normal in that direction. But it wasn’t consistent in that if I moved the shift shaft to reverse and then back to forward, it would again allow the prop to be turned without locking into gear unless I tried it a few times. Overall, after experimenting a bit more I found that I had to hold the shift shaft tight to the counter-clockwise (reverse gear) position while moving the prop for it to engage the cog. My impression was that this is pretty sensitive about needing me to hold finger pressure to keep the shift shaft fully in position. Question is, will the shift cable would normally hold pressure on the shift shaft so perhaps this is not really an issue. Did not have any trouble with it not engaging when on the water. Just listing this symptom in case it implies something is worn. When it engages the cog with me holding the shift shaft tight, it is a solid engagement.

The more I experimented with the above, the more I started wondering if i'm imagining extra problems that don't exist, but figured I'd ask what else I should check short of dismantling the entire lower unit.

My engine incidentally is a Mercruiser 5.7l (2bbl carb).

 

[Candy Gramformongo]

Things don't normally go wrong simultaneously without being related. So the coupler failure is very likely related to the drive being locked up. You seem to suspect that the coupler failed on its own first, which then caused the drive to temporarily lock up. I would suspect the opposite, and tear the drive down expecting to find something wrong inside which caused the lock up and then the coupler failure, in that order.

 

[ScottinAZ]

Things don't normally go wrong simultaneously without being related. So the coupler failure is very likely related to the drive being locked up. You seem to suspect that the coupler failed on its own first, which then caused the drive to temporarily lock up. I would suspect the opposite, and tear the drive down expecting to find something wrong inside which caused the lock up and then the coupler failure, in that order.

this exactly.... SOMETHING was causing the drive to be stiff.... At the very least, pull the plugs and drain the oil for an inspection. I would also be at the very least pulling the top cap and taking a look at what I can see... Changing a coupler isnt so much fun that I would want to be doing it regularly. It could be something as simple as the drive was misaligned, which will smoke a coupler and the input shaft bearings given enough time....

 

[Bondo]

I didn't see my exact outdrive symptoms when searching past threads, so I'm posting this for advice on next steps.

I have a 1996 Alpha One Gen 2 outdrive. While towing a tube on the lake, a few hours into our day, we heard a bang, lost drive suddenly, had a bad smell of burning rubber, plus smoke coming from coupler end of engine. The coupler had been replaced when we did the engine rebuild over the winter, but it wasn't an OEM Mercruiser coupler. I expected from this that the cheap coupler had failed and that was my first problem, but that's not why I’m posting this question.

• My concern is that after removing the outdrive I could not turn the yoke by hand at first. After multiple tries I was able to get it moving after feeling like it was slowly freeing up. No noises. I could not find any cause for why it wasn’t turning at first. I could not recreate the problem when turning by hand.

Questions:

• Should I be worried about it initially being bound up even though the outdrive eventually now finally turns OK by hand?
• Are there some things I can check to narrow down if there is an issue with the lower unit? I know how to remove the gearsets in the upper as I've done it before, but I've never tackled the lower unit. See below for what I’ve checked so far.

Longer explanation:
To get started on the coupler replacement, I removed the outdrive from the boat. Before progressing to the Coupler which I’m sure is ruined, I tried spinning the yoke shaft on the outdrive by hand to make sure that turned without issue. Problem is, I couldn’t turn it in either direction no matter if the shift shaft was placed in forward or reverse direction. If I reached around to the prop it spun easily in either direction, which also seemed weird. After trying a few more times and turned the yoke as hard as I could, it seemed to slowly free up and then start turning normally by hand. I can’t figure out what caused it to bind up at first, so looking for advise as to whether this could be expected from having pulled the outdrive, or if I’m facing an intermittent problem? I could not recreate this issue once I got it moving the first time.

BTW:

• I removed the top cap and saw nothing wrong with the gear oil. No bad smells either.
• Gear oil level was aligned with the top of the upper plug.
• I have drained the gear oil to check for any metal bits – gear oil looked clean and free of debris
• There is a bearing at the very top (the one with the cup installed in the top cover) which seemed to have some wiggle by hand, but this doesn’t seem to be so bad as to jam things up.
• I had changed all seals in the upper unit this past winter. Bearings all felt good at that time. I did not touch the lower unit bearings.

Additional finicky behavior?
This may be unrelated to the above, but to get the prop to turn with the yoke, I found that if I manually turned the yoke a bit more aggressively while the shift shaft was set for forward it would engage the cog and so felt normal in that direction. But it wasn’t consistent in that if I moved the shift shaft to reverse and then back to forward, it would again allow the prop to be turned without locking into gear unless I tried it a few times. Overall, after experimenting a bit more I found that I had to hold the shift shaft tight to the counter-clockwise (reverse gear) position while moving the prop for it to engage the cog. My impression was that this is pretty sensitive about needing me to hold finger pressure to keep the shift shaft fully in position. Question is, will the shift cable would normally hold pressure on the shift shaft so perhaps this is not really an issue. Did not have any trouble with it not engaging when on the water. Just listing this symptom in case it implies something is worn. When it engages the cog with me holding the shift shaft tight, it is a solid engagement.

The more I experimented with the above, the more I started wondering if i'm imagining extra problems that don't exist, but figured I'd ask what else I should check short of dismantling the entire lower unit.

My engine incidentally is a Mercruiser 5.7l (2bbl carb).

Ayuh,...... My 1st guess would be a dry dragging impeller,....

 

[Bt Doctur]

or you didnt set the rolling torque correctly and seized the input bearings

 

[nola mike]

But it wasn’t consistent in that if I moved the shift shaft to reverse and then back to forward, it would again allow the prop to be turned without locking into gear unless I tried it a few times. Overall, after experimenting a bit more I found that I had to hold the shift shaft tight to the counter-clockwise (reverse gear) position while moving the prop for it to engage the cog. My impression was that this is pretty sensitive about needing me to hold finger pressure to keep the shift shaft fully in position. Question is, will the shift cable would normally hold pressure on the shift shaft so perhaps this is not really an issue. Did not have any trouble with it not engaging when on the water. Just listing this symptom in case it implies something is worn. When it engages the cog with me holding the shift shaft tight, it is a solid engagement.

Normal behavior

this exactly.... SOMETHING was causing the drive to be stiff.... At the very least, pull the plugs and drain the oil for an inspection. I would also be at the very least pulling the top cap and taking a look at what I can see... Changing a coupler isnt so much fun that I would want to be doing it regularly. It could be something as simple as the drive was misaligned, which will smoke a coupler and the input shaft bearings given enough time....

He already did all that and it was fine. Agree with alignment, op didn't mention if it was checked

Ayuh,...... My 1st guess would be a dry dragging impeller,....

Agreed. Not easy to turn the input shaft. Op, remember that when you turn the input shaft you're turning everything in the drive except for the prop when you're in neutral. If something in your drive seized enough to take out a coupler, I'd be surprised if it spontaneously unseized with you turning it by hand and left no evidence

 

[BenchmarkMarine]

Thanks everyone for your inputs. To answer the lingering question - yes we did set the alignment when installing the drive this Spring.
I plan to dismantle the upper unit to check that. Not sure if I will tackle the bearings and gears at the lower unit. Looking at the service manual, the lower unit (bottom gear and bearing assemblies) seemed harder to do. Thinking about either taking it to a shop, or giving in and buying a new sterndrive. Just seems to be too many things that could go wrong for a novice like me. Usually in the end the sticker shock will give me the courage to reconsider and tackle such things on my own.
I appreciate all the insights.

 

[Grub54891]

Do you have the tooling for setting gear lash and rolling torque?

 

[BenchmarkMarine]

Do you have the tooling for setting gear lash and rolling torque?

I used an in-lb torque wrench to set the rolling torque. I didn't do anything for the gear lash or any shims since I had only changed the seals, the short yoke, and the universal joint. The short yoke was replaced because the old leaking seal had worn a gouge into the riding surface of the yoke. The u-joints showed no sign of issue, but I replaced the one at the short yoke because I was halfway there.