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Prop shaft coupling spins but prop shaft does not. 72 E27.

Cajunspike

Member II
Was coming back from only my 2nd outing on the boat.
Engine was running fine.
Got back to the dock and was lined up to reverse into the slip.

Shifted into reverse and got no boat movement.
I could hear the tranny make the reverse sound, but no thrust.

Long story short, the prop shaft coupling is intact.
The engine 1/2 spins.
The prop shaft 1/2 spins.
The prop shaft does not spin.

On another boat I had, the prop shaft half coupling was clamped to the prop shaft by a large bolt.
Then a pin bolt was screwed into the coupling to positively lock the coupling to the shaft.

As of this writing, I do not know if there is a pin bolt in place or not.

Anybody has a a doc/video/experience on how to lock the prop shaft to the prop shaft half coupling?
 

Alan Gomes

Sustaining Partner
Was coming back from only my 2nd outing on the boat.
Engine was running fine.
Got back to the dock and was lined up to reverse into the slip.

Shifted into reverse and got no boat movement.
I could hear the tranny make the reverse sound, but no thrust.

Long story short, the prop shaft coupling is intact.
The engine 1/2 spins.
The prop shaft 1/2 spins.
The prop shaft does not spin.

On another boat I had, the prop shaft half coupling was clamped to the prop shaft by a large bolt.
Then a pin bolt was screwed into the coupling to positively lock the coupling to the shaft.

As of this writing, I do not know if there is a pin bolt in place or not.

Anybody has a a doc/video/experience on how to lock the prop shaft to the prop shaft half coupling?
Someone else may have more specific advice for you, but for now I would just say to be darn sure that the prop shaft does not slide out of the coupling and out of the boat! You would then be in a real world of hurt. Perhaps putting a hose clamp on the shaft as a safety would be a wise thing to do while you get this all sorted out.
 

Cajunspike

Member II
Only got this boat in December 2017, so still learning everything about it.

I've worked on a prop shaft coupling before on my lafitte skiff so not entirely unfamilar with the concept.

I just don't know the facts on this E27.

Is there a keyway on the prop shaft coupling end?

Is there a pinch bolt to bind the coupling half to the prop shaft?

Is there a positioning/lock bolt from the 1/2 to the prop shaft on the rear coupling half?

Working space is limited. I only have a couple of inches I can push the prop shaft backwards to remove the coupling.
Caution duly noted.
 

supersailor

Contributing Partner
There should be a key in a slot that is in both the shaft part of the slot and the prop part of the slot. The shaft and prop are tapered at this point and the prop nut drives the prop tight onto the shaft. The key transfers the torque to the prop.

The prop nut is likely loose letting the prop spin loose when it backs beyond the reach of the key. It could be that the key is broken. In any case, you are in grave danger of losing the prop. I would not use the engine again until the prop is checked. My new prop was $793.
 

Kevin A Wright

Member III
Hi,

It's been over 25 years since I replaced the shaft and coupling on my E27 when I repowered, but memory says there is both a key and a set screw/bolt holding the shaft to the coupling. Sometimes the retaining bolt is also wired in place to prevent it from backing out. And yes access IS limited.

Before you do much of anything, if you don't have one, stick a hose clamp on the shaft between the coupling and the packing gland on the shaft log. Just real cheap insurance if something goes wrong so you don't have your shaft back out and sink your boat.

The other thing I'd look at is if you wrapped your prop with something? Normally I'd think the friction from the packing gland and cutlass bearing would be pretty minimal. Certainly it took something to shear the key and normally there is enough rust, crud to almost weld the shaft to the coupling (couplings are normally not stainless) and it should still turn? So something serious must be restricting the prop.

Or are you sure the shaft is turning and not just vibrating? Could it be you lost your prop nut (and the prop) when you went into reverse? If the light was right I used to be able to see my prop if I got down on my belly on the dock. Might be worth a look to make sure it is still there and not wrapped with line.

Good Luck!

Kevin Wright
E35 Hydro Therapy
 

Cajunspike

Member II
Hi,

It's been over 25 years since I replaced the shaft and coupling on my E27 when I repowered, but memory says there is both a key and a set screw/bolt holding the shaft to the coupling. Sometimes the retaining bolt is also wired in place to prevent it from backing out. And yes access IS limited.

Before you do much of anything, if you don't have one, stick a hose clamp on the shaft between the coupling and the packing gland on the shaft log. Just real cheap insurance if something goes wrong so you don't have your shaft back out and sink your boat.

The other thing I'd look at is if you wrapped your prop with something? Normally I'd think the friction from the packing gland and cutlass bearing would be pretty minimal. Certainly it took something to shear the key and normally there is enough rust, crud to almost weld the shaft to the coupling (couplings are normally not stainless) and it should still turn? So something serious must be restricting the prop.

Or are you sure the shaft is turning and not just vibrating? Could it be you lost your prop nut (and the prop) when you went into reverse? If the light was right I used to be able to see my prop if I got down on my belly on the dock. Might be worth a look to make sure it is still there and not wrapped with line.

Good Luck!

Kevin Wright
E35 Hydro Therapy

Just paid a diver to inspect the prop under the boat. Nothing underwater unusual found. Nothing tangled in the prop(doesn't mean something didn't get caught and fall away).
Prop is in correct position and tightly bolted to the shaft.

As a courtesy, he helped locate the issue after coming up.

I was able to visually verify the coupling spinning but shaft is not following along.
Will verify shaft is still movable on next visit.

Just looks like the key was sheared I'm thinking.

Closer inspection and pics on next visit.

Thank you everyone.
 
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Kevin A Wright

Member III
Sounds like it. Hope you have a friend who's a little person. Or has arms that are 7 feet long with an extra set of elbows. Good luck!

Kevin Wright
E35 Hydro Therapy
 

toddster

Curator of Broken Parts
Blogs Author
I replaced the old shaft coupling with a Moyer split coupling, but IIRC, the shaft comes with a "dimple" punched into it, and a set screw from the coupling gets tightened into the dimple. Nothing so sturdy as a key. If your shaft doesn't have the dimple, then only the friction of the set screw(s) would hold it in place. There is no good access at all to work on the coupling, at least on my boat, and it pretty much takes all day to change. I have photos somewhere, but not sure if they show the detail at the coupling. I was more concerned about the other end, at the time.
 

JPS27

Member III
Sounds like perhaps your key is not there any longer, or never was and your set bolts are loose? From what I've seen we generally have a key with keyways on shaft and coupling and two set bolts with seizing wire to hold. I posted in a recent thread how my misaligned engine (unbeknownst to me) over time wore down the key AND the keyways. My obsessive compulsive relationship with my 27 led me to discovering this fact with an extendable mirror that showed the damage that was occurring. Follow the advice on the hose clamp, for sure. Although depending on your prop and shaft length your shaft may not go more than several inches before it hits the rudder. You'll be dropping the rudder most likely to fix this. But once fixed you'll know it's been done right.
 

toddster

Curator of Broken Parts
Blogs Author
There may have also been a key at the coupling end that I just don't remember. I.e. if it was "normal" I probably didn't have to worry about it. (The old shaft/coupler/prop assembly was a weird PO mashup that I hadn't been expecting.)
 

Mark F

Contributing Partner
Blogs Author
Hi Cajunspike,

My 1976 E27 has a 3/4" prop shaft with key slots in both ends.
 

Teranodon

Member III
Here is what it looks like on my E34. As others have noted, there is a set screw. Presumably, yours is either loose or rolling around in the bilge.

Shaft coupler.jpg
 

Cajunspike

Member II
Terandon, your photo is what I have worked with before on my other boat and hope thats how it is.

I'll put a light down there and see what I have to work with.

Again everyone, sincere thanks for your input.

I know if I have to pull the coupling off to replace the key, it will be a b_itch.
 
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Cajunspike

Member II
Anybody know of a write up or video on how to remove/replace/fix the prop shaft coupling on an E27?
Access to the area of coupling is horrendous.
 

Kevin A Wright

Member III
Don't know of any videos but it is pretty straight forward. Undo the bolts and slide it back. Be sure to put a hose clamp on the shaft so it doesn't slide too far back into the stuffing box.

The real thing is access. Especially since if it as rusted up as mine was, I needed to get a hot wrench in there to get the bolts freed up (oxyacetylene torch).

Here's the big hint, the bulkhead or firewall behind the engine is not structural. Take a sawsall or jigsaw to it and enlarge the opening enough that you can lay on top of the engine and work on the shaft while laying on top of the engine. This is also nice in the future when you need to tighten your stuffing box every couple of years. The only drawback is this lets more engine noise into the cockpit area. You can close it back up with a sheet of plywood or something screwed to the original fiberglass so you can remove it to do future maintenance.

Good Luck!

Kevin Wright
E35 Hydro Therapy
 

Cajunspike

Member II
Don't know of any videos but it is pretty straight forward. Undo the bolts and slide it back. Be sure to put a hose clamp on the shaft so it doesn't slide too far back into the stuffing box.

The real thing is access. Especially since if it as rusted up as mine was, I needed to get a hot wrench in there to get the bolts freed up (oxyacetylene torch).

Here's the big hint, the bulkhead or firewall behind the engine is not structural. Take a sawsall or jigsaw to it and enlarge the opening enough that you can lay on top of the engine and work on the shaft while laying on top of the engine. This is also nice in the future when you need to tighten your stuffing box every couple of years. The only drawback is this lets more engine noise into the cockpit area. You can close it back up with a sheet of plywood or something screwed to the original fiberglass so you can remove it to do future maintenance.

Good Luck!

Kevin Wright
E35 Hydro Therapy

I thought about cutting the back wall, but not in conjunction with laying on top the motor.
Was contemplating removing the tank and going in thru that area.
But I see where this will work.
Input MUCH appreciated.

I did find the 'pinch bolt' thru the coupling to the shaft is missing.
Also the coupling spins freely on the shaft, so once there is space to work, it should come off easy to replace the key.
 
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Mark F

Contributing Partner
Blogs Author
Hi Cajunspike,
If you are thinking about pulling your fuel tank through the bulkhead/firewall behind the engine it is possible. I just removed the gas tank in my 1976 E27. You will need to cut the wall out completely from side to side. It is just fiberglass - no plywood, so it is pretty easy.
tank1.jpgtank3.jpg
 

Cajunspike

Member II
Latest update

Part 1 of the issue, besides access, was heat.

So I got the bright idea to go work on the boat at night.

Also put an air condition unit in the door frame while I was there.
Issue solved..

Part 2 went like this.
Leaning over the motor, I cut away part of the back engine box using an oscillating tool.
Only removed enough to get tools in the area around the coupling.

This gave access to the coupling work area.
Managed to get all 3 coupling bolts out. Had to use the engine hand crank to hold the engine to break the last bolt loose.

With the bolts out, how do you remove the coupling when there is no room to pull it off the shaft?
Pull all 8 motor mount bolts.
Pull both muffler bolts.
Pull the outlet water line.
Drag the engine fwd an inch or two.

Voila, coupling comes off in your hand.

Final analysis:
Rear coupling pinch bolt unscrewed and fell off. Was NOT wired in place.
Prop shaft backed out of coupling and became disengaged from coupling due to very short coupling key.

While the slot for the shaft key was about 1.5" the actual key was only about 3/4th of an inch.

So now I'm thinking about ordering a new clamp on coupling instead of going back to the original design.
Every person who offered their input, thanks and much appreciation.

How it looks now, with the coupling removed, back wall cut, and engine slid forward.
couple5.jpg


The cause of all this work. Look how short the key is.
couple6.jpg



I had just replaced the fuel tank about a month ago. Didn't look forward to removing it again. Besides that I wouldn't fit in the port locker
to get in the fuel tank area if it was removed. :)
All work was done laying on top of the motor.
 
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Alan Gomes

Sustaining Partner
So glad your prop shaft did not slide out of the boat and put you on the bottom! Great that you caught it when you did.
 
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