Prop shaft turns when engine is in gear

[sticknrudder]

Is this normal? '85 Skier with a PowerSlot that I just bought. I was checking the driveshaft alignment when I noticed no matter whether I put it in neutral, forward or reverse the shaft spins freely. Wouldn't it engage the engine and make it hard to turn?

Thanks

[waterlogged882]

Is this normal? '85 Skier with a PowerSlot that I just bought. I was checking the driveshaft alignment when I noticed no matter whether I put it in neutral, forward or reverse the shaft spins freely. Wouldn't it engage the engine and make it hard to turn?

Thanks

Creep. Common in the Velvet Drive. You can rebuild or run with it. I have run many hours on a creeper.

Do not put in gear, out of water.

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[sticknrudder]

So when running it should engage properly?

When you say don't put in gear out of the water, is it bad to do even with the engine shut off?

Thanks

[sticknrudder]

One other thing is the transmission fluid is currently only half full due to a leaking line. The line is on order. Would low fluid cause it to creep?

[waterlogged882]

So when running it should engage properly?

When you say don't put in gear out of the water, is it bad to do even with the engine shut off?

Thanks

Yes. Engagement and operation would be normal operations.

You can engage the transmission with the engine off. A running engine and in gear makes a heck of a squeal from the dry strut bearing.

All good otherwise.

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[waterlogged882]

One other thing is the transmission fluid is currently only half full due to a leaking line. The line is on order. Would low fluid cause it to creep?

Maybe but I think not so much. Low fluid typically will cause slipping.

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[sticknrudder]

Could you please explain the difference between creep and slip?

[waterlogged882]

Could you please explain the difference between creep and slip?

Creep is what you are seeing now. In particular when in neutral the shaft/prop still turns just a little bit. I have seen creep move a boat in neutral at idle.

Slip is when the friction/clutch plates get hot or worn, and while under a load, the transmission will slip a little not propelling the boat forward. One would notice this in a turn or a pull from a dead stop. You can usually feel (and hear engine RPM increase) slippage in the performance of the acceleration.

Dirty fluid is a common cause of slip, where the fluid may not have been changed for several years. I know of folks that may have never changed fluid in the course of their ownership, upwards of 5 years or so. I change mine every other season or at approximately 100 hours of operation.

I work a boat hard. I take care of the equipment but I work an engine hard. That is the beauty of the solid 351W to me. The Velvet Drive is also a tough transmission. Simple enough to rebuild DIY.


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[sticknrudder]

Thank you for the detailed explanation. That’s what I thought creep was, which is why I’m confused. With the engine odd, the shaft is spinning freely when I turn it with my hand with it in gear. I would think if it were creeping it would be engaging in neutral not disengaged in gear. Is it just that it acts differently when the engine is running?

[waterlogged882]

Thank you for the detailed explanation. That’s what I thought creep was, which is why I’m confused. With the engine odd, the shaft is spinning freely when I turn it with my hand with it in gear. I would think if it were creeping it would be engaging in neutral not disengaged in gear. Is it just that it acts differently when the engine is running?

Engine running, even at idle, there is a pump inside of the transmission, thus creep in neutral. Engine off...no pump to circulate fluid.

As a side note, when changing fluid or a rebuild, do not run the engine without fluid (first) in the transmission.

[sticknrudder]

That makes sense. Thank you!

As a side question, I was trying to separate the coupler between the transmission and the prop shaft to check the engine alignment. The coupler seems stuck. Any tricks for getting it off?

[waterlogged882]

That makes sense. Thank you!

As a side question, I was trying to separate the coupler between the transmission and the prop shaft to check the engine alignment. The coupler seems stuck. Any tricks for getting it off?

I think you are saying the shaft coupler is stuck onto the transmission flange.

Couple of points. You can use a pry bar or similar to separate. I like to think the shaft would slide back away from the transmission without a lot of effort..but... My approach is to be conscientious of how the flange/shaft come apart...take close notice; does the shaft spring in one direction or the other or (once unstuck) does it slide straight back. That tells me how the shaft was aligned to the transmission. If it springs significantly in a particular direction, there's your answer. Seeing as you have the gear reduction unit, there is not a lot of room for that particular observation, but you see the point.

The flanges have a male/female fitment. They are not two flat surfaces. There is a particular and delicate fit when re-mating the flanges.

But here is another thing I consider, contrary to some folks' beliefs...if I don't feel a vibration in the boat while underway, I leave well enough alone.

Alignment (or misalignment) also has an affect on the strut bearings. For an 85 year make, they are overdue replacement, being proactive. At that point, alignment verification is out the window, remove and replace the strut bearings, and then a fresh alignment is in order. If you remove the shaft to replace the bearings, a new dripless shaft seal is a suggestion. No better time than at that point.

Old and new for reference and comparison. I did this swap a while back. There is one on each end of the strut.

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[waterlogged882]

To check your alignment easily, loosen the four bolts and stop there. Regardless of how large or small the gap is, the gap should be within 0.003-5" at four points. Take a measurement with feeler gauges at each bolt hole and check the gap. All of the measurements should be close as stated. When you get to a second (sanity) check, rotate the shaft 180 degrees and check the gaps again.

There are several boob-tube videos on this and folks will vary in technique, all serving the same purpose and results. I am an old school guy.

I keep the flanges close together and roll the shaft. When I find a variance, I adjust the engine mounts to better align, roll and check again.

There is always the possibility that the engine mounts could be seized and not cooperate with wrench movement. That is a problem. So weigh your scenario and any associated risks before taking it all apart. If the strut bearings need replacement, bite the bullet. It is all easy, just a bit trying on one's patience.

One important thing...align or move the engine to the shaft flange...not the flange to the engine. The shaft is directed by the strut, which is the basis of all things in the driveline.

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[sticknrudder]

What’s strange is the transmission was replaced a couple years ago, but they said they didn’t use a feeler gauge to align it and there was some vibration. So I was going to try to make sure it’s aligned before water testing. I thought the coupler would come off the transmission flange easier. Seems a bit frozen.

I think you’re right, probably do need those bushings. There’s a little wiggle in the shaft, not much but just a little. And when I turn it one direction it squeaks some.

[waterlogged882]

What’s strange is the transmission was replaced a couple years ago, but they said they didn’t use a feeler gauge to align it and there was some vibration. So I was going to try to make sure it’s aligned before water testing. I thought the coupler would come off the transmission flange easier. Seems a bit frozen.

I think you’re right, probably do need those bushings. There’s a little wiggle in the shaft, not much but just a little. And when I turn it one direction it squeaks some.

From your description and the symptoms, I'd say an alignment is in order. You are asking all the right questions. It could be frozen by virtue of misalignment and a forced reassembly. There is a male/female joining of the flanges. Use a pry bar and pop it loose. Big hammer with gentle force...just enough to break the bond.

Take it apart, service it and enjoy the work. That is what I enjoy about the off season...work and improvements.

There are a couple of easy ways to remove the flange from the shaft, then remove the prop, pull the shaft out the back and do the maintenance. You can do all of this DIY. It's easy and plenty of folks here and on boob-tube to get you back in business. I have talked a lot of folks through this process over the phone. It's that easy.