Spun Prop or Shaft/Shifter Issue? Sea Ray Mercruiser Alpha One

[HokiePilot]

A little background on the boat....I have a 1990 Sea Ray and I have done most of the maintenance myself. Last fall I pulled the lower and replaced the impeller, greased everything up and and rebuilt the carb before laying it up for the winter. I did keep it running periodically so there wasn't a long sit period.

Since I have owned the boat I noticed that every so often in a high speed turn normally with a tuber being pulled the engine would rev up. I had always dismissed this as the prop coming out of the water. Now hindsight tells me it may have been something else. I randomly bump the mud bottom or trees in my lake since it is very shallow in some places. The other day I was running the boat home after tubing and noticed it had "revved up" more than normal, while at a good speed the gear slipped out and I immediately dropped it into neutral. The boat gets no forward or reverse motion while in gear and only revs.

Here are some things I have noticed:

-Engine runs fine, no knocking or and grinding noises in the drive
-Shifting cables from the handle to the engine all appear to be operating correctly
-There is no apparent "clunking into gear noise" when shifting into forward or reverse
-When engine revs impeller still spews water out of the prop hub and seems to be operating correctly
-With the engine off and in gear, the prop wont spin, in neutral it spins freely


Thanks for any help or insight you can provide!!
-Zack M

 

[Bondo]

A little background on the boat....I have a 1990 Sea Ray and I have done most of the maintenance myself. Last fall I pulled the lower and replaced the impeller, greased everything up and and rebuilt the carb before laying it up for the winter. I did keep it running periodically so there wasn't a long sit period.

Since I have owned the boat I noticed that every so often in a high speed turn normally with a tuber being pulled the engine would rev up. I had always dismissed this as the prop coming out of the water. Now hindsight tells me it may have been something else. I randomly bump the mud bottom or trees in my lake since it is very shallow in some places. The other day I was running the boat home after tubing and noticed it had "revved up" more than normal, while at a good speed the gear slipped out and I immediately dropped it into neutral. The boat gets no forward or reverse motion while in gear and only revs.

Here are some things I have noticed:

-Engine runs fine, no knocking or and grinding noises in the drive
-Shifting cables from the handle to the engine all appear to be operating correctly
-There is no apparent "clunking into gear noise" when shifting into forward or reverse
-When engine revs impeller still spews water out of the prop hub and seems to be operating correctly
-With the engine off and in gear, the prop wont spin, in neutral it spins freely


Thanks for any help or insight you can provide!!
-Zack M

Ayuh,... Welcome Aboard,... The testin' I hi-lighted, was this on the wagon,..??

Is yer prop of the ole style with a pressed in rubber hub, or of the newer plastic hub variety,..??
Have ya pulled the prop, 'n looked it over,..?? plenty of grease on the prop shaft,..?

The line I underlined, sounds like plain ole ventilation from turnin' to sharp, to fast,...

At this point, Ya might have a bad prop hub, or a blown motor coupler,.....
Answers to my questions will help narrow it down,....

 

[HokiePilot]

The testing was done in the water and then again when I towed it home and got it on the lift. Unfortunately I won't be able to get it in the trailer until I tow it across the lake again to the marina.

I think I can get the prop off in the lift, just would have to be careful not to drop anything! I figured I would toss my issues out here before I attempted anything. I believe it has a plastic hub not rubber, I pulled the prop as well last fall and it seemed in good shape, I got as much grease on it as I could then added some more. My next step was going to pull the prop and see what I can find out, it seems to be the extent of things I could accomplish without getting to boat completely out of the water.

 

[Texasmark]

A rubber hub is pressed into the prop shell and is designed to slip during contact with an obstruction. Putting the shifter in N allows the rubber to reseat and returning to the drive gear of choice you continue on your way. Opinion: Only in extreme circumstances will the hub continue to slip when drive power is returned.

A plastic hub is made of a brass insert in a plastic medium which slides into and out of shells of different parameters allowing you to have a few props and with hub options, allow these few props to fit numerous installations. Opinion: The idea is sound for the selling agency, but for the user it sucks! The brass and plastic are non forgiving and it sounds to me like you started working on your plastic over numerous outings and finally finished it off.

On what you said about the shell not spinning in gear when turned by hand you are comparing 1 hand power to many 10's of horsepower.....apples and oranges. Your analysis may or may not have merit....requires inspection to determine.

You ought to be able to access your prop with the outdrive tilted all the way up and your standing in shallow water, or floating with a life jacket in deep water.

Pull the prop and check the hub. If plastic, push it out and look it over. If damaged insert a new one. If rubber, you will need to see a prop shop. So you say "Geez if I had a plastic and not rubber I could do my own repair and be on my way!" My answer is how much abuse will a rubber take with no memory and continue to serve the purpose? I'll take the rubber. I have 3 SS rubber props and one plastic which sits on the shelf for my engine.

From what you described I'm guessing you have a plastic hub and it is stripped.

Mark

 

[HokiePilot]

You guys are awesome, thanks for the help. I'm going to pull the prop today. I'll post pictures and let you know what I find!

 

[HokiePilot]

No Title

To my untrained eye it's hard to tell if the bushing is bad. I tried to spin the prop with the nut off and in gear to see if it would spin on the bushing but it didn't. I could clearly hear the impeller spinning so I'm confident the drive shaft is intact. Maybe it needs more rpm to cause the slip?

 

[HokiePilot]

I ran out of time before heading into work. I'll get the center pulled out this evening

 

[Bondo]

I ran out of time before heading into work. I'll get the center pulled out this evening

Ayuh,.... Drive the black plastic piece outa the prop,....

In yer last picture, it Does sorta look shifted outa place,...
If yer Lucky, that's the problem,...
Another new hub kit will get ya back on the water,....

If yer not so lucky, ya might be lookin' at pullin' the motor, to replace the coupler,....

 

[HokiePilot]

Uh never enough time for the boat work....I was unable to get the plastic hub out. I need to find a better socket to drive it out with. Im out of town for the next couple of days and will update this weekend.

 

[Texasmark]

Uh never enough time for the boat work....I was unable to get the plastic hub out. I need to find a better socket to drive it out with. Im out of town for the next couple of days and will update this weekend.

If you are having a problem driving it out that can be a heads up on a damaged insert. Should fit snugly but not hammer banging tight!

 

[HokiePilot]

No Title

Here are the pictures, I ran the prop by a local shop and he said that I definitely spun my prop. I had to hammer it out.

Before I removed the prop I also noticed that while it did lock into forward/reverse gear, I was able to spin the prop with some pressure and I could hear the shaft spinning the water impeller. After I told him this he said there should be no way I would be able to do that and recommended I bring the boat in so he could check it and possibly replace the lower due to a bad drive. Which I assume he was getting at what was previously mentioned before??

If yer not so lucky, ya might be lookin' at pullin' the motor, to replace the coupler,....

If this is the case I was gonna stick it on the trailer, take it down to the shop and hope my insurance would pick it up. He estimated the cost at $1700. I only paid $2500 for the boat so without insurance the job isn't really worth the money. Should I just replace the hub before I make any other drastic moves?

 

[Texasmark]

Should I just replace the hub before I make any other drastic moves?

Yesssssssss Plastic is a lot more forgiving than your crank shaft or drive shaft/gearing which are heat treated, cast steel or ss machined rod. When you get the insert problem fixed, the gear on outboards works like this and will probably work just fine......remembering that when you are turning the prop by hand you are applying pressure in the opposite direction as the engine so don't get hung up on the cw/ccw I'm using below. If the engine is driving the prop the directions will be exactly opposite.

In N prop turns freely both directions. Should be absolutely no noise associated with it spinning by hand.

In all gears you can grasp the blades and push in toward the lower unit and have 1/4" more or less, of spring loaded fore aft travel. You push it in and it springs back. See F gear below as to why this is ok.

​In F gear you cannot turn the prop ccw (looking from the rear) but you can turn it cw and in doing so the prop and shaft move back and forth slightly as compared to the LU. While turning you hear a clicking noise. This is the overrun clutch and the drive from F gear to the prop shaft is like a saw's teeth; sloping in one direction and straight down the other. As you turn the prop and the gear rides up and down the sawtooth the shaft and prop move back and forth with respect to the LU housing just slightly as mentioned. The prop is locked to the crankshaft of the engine when attempting to turn the prop ccw by hand. On cw rotation, the overrun clutch is there for when you decelerate allowing the prop to follow the water pressure on it while the engine slows down well below the proportional prop speed. If you didn't have this and cut the throttle fast, you could wind up with a mouth full of windshield....you just put the brakes on big time!

Farm tractors like the Ford N series back in the late 1930's and on (still a solid market for used machines today), had transmission driven Power Take Offs (PTOs) and when connected to a rotary mower cutting the throttle didn't necessarily slow you down, or the brakes didn't necessarily stop you until the blade of the mower quit spinning and propelling the tractor. To remedy this problem an after market "overrun clutch" was installed between the PTO drive and the drive shaft to the mower so any time the mower was turning faster than the engine the overrun clutch disconnected the drive line and while doing so went click, click, click. "Now you know the rest of the story"....Paul Harvey...RIP!

In R on an outboard for sure and probably I/Os also, first of all you don't attempt to put the shifter in R unless you do it slowly and someone is rotating the prop if the engine is not running....and if you have your hands on the prop you definitely don't want the engine running. The reason why is because you have a cog and tooth arrangement in R with straight rectangular interfaces and for the tooth to slip into the cog and connect the prop to the prop shaft, the two must be lined up. Then the shifter will easily go all the way into R; otherwise the service manuals say that shift linkage damage could result. Once there the prop will not turn in either direction unless the engine crankshaft also turns.

Somewhere down the line I saw a different R mechanism where it had the over run clutch just like F gear. If you have that, it will act just like F gear, just in the opposite direction.

Let us know what happens when you run your rebuilt prop.

Mark

 

[HokiePilot]

I can find replacement plastic sleeves but I should probably just get an entire new kit like the one below.

http://www.iboats.com/HUB-ASSY-KIT-M...view_id.480360

I noticed that the kit above does not have the metal insert inside the plastic. Is this something I have to get pressed in separate or cut out of the old plastic hub? It almost looks like the replacement parts don't need to have a metal insert? Below is a picture of what I pulled off the old prop.

http://www.iboats.com/XHS-II-Hub-Ki...6238537--session_id.343151859--view_id.798320

Here is the what looks like an actual OEM replacement but with out the nut and tab washer.

 

[Bondo]

I can find replacement plastic sleeves but I should probably just get an entire new kit like the one below.

http://www.amazon.com/Quicksilver-Me...UISER+HUB+KITS

I noticed that the kit above does not have the metal insert inside the plastic. Is this something I have to get pressed in separate or cut out of the old plastic hub? It almost looks like the replacement parts don't need to have a metal insert? Below is a picture of what I pulled off the old prop.

http://www.amazon.com/XHS-Mercury-Ma...eel+XHS+II+202

Here is the actual OEM replacement but with out the nut and tab washer.

Ayuh,.... Have ya looked here at iboats for a new hub kit,..?? somebody's gotta pay Our rent, might as well be you,....

If ya buy a Kit, the pieces will interchange, metal insert or not,...

 

[HokiePilot]

Ayuh,.... Have ya looked here at iboats for a new hub kit,..?? somebody's gotta pay Our rent, might as well be you,....

If ya buy a Kit, the pieces will interchange, metal insert or not,...

I just changed the links before I saw your post haha...sorry! I didn't realize iboats had them, I would much rather buy them on here!

Here are the 4 I'm looking at. Not really sure which is the best route. Any advice?
http://www.iboats.com/HUB-ASSY-KIT-M...view_id.486331
http://www.iboats.com/XHS-II-Hub-Kit...view_id.798320
http://www.iboats.com/Turning-Point-...view_id.717433
http://www.iboats.com/HUB-ASSY-KIT-M...view_id.480360

 

[Bondo]

Ayuh,.... I've only used the top one, 'n the bottom one before,.....

That said, I believe any of the 4 would work,....

 

[HokiePilot]

order placed, I'll let you know how it goes

 

[HokiePilot]

Update:

Prop hub has been replaced, it definitely needed it. Unfortunately it did not fix my problem.

As far has I can see with my limited experience troubleshooting the shift shaft integrity is good. Boat goes into gear when off. In forward the prop clicks when spun clockwise and locks with turned ccw, although it doesnt take much pressure to continue to spin it ccw without the drive stopping it. Any information yall could give me on what to expect with the mechanics would be great. It seems to me that the drive coupler is bad.

 

[Bondo]

Ayuh,..... Pull the drive,.... There should be evidence of the coupler failure on the splines,....

 

[Texasmark]

May not have to pull the drive to fix the problem. The ccw resistance, cw clicking is correct. The ability to turn ccw without the engine turning also is not ok! However if you are turning the engine over, that's ok. But being an I/O with a large engine that probably didn't happen.

The drive shaft is coupled through a thing called a clutch dog. It is pinned to the prop shaft with a ss pin that runs through a hole in the shaft. On either end of the dog are gears to mate with the rear of both F and R gears. The shifter is twisted to function and is a cam/cam follower apparatus. The cam has 3 detents and each is a different distance from the pivot point. By being a different distance, the cam follower moves fore and aft as you shift with F being closest to the front of the LU housing and R being farthest.

In F the spring in that assembly pushes the dog into the rear of F gear where it picks up a set of teeth resembling a saw blade. Each tooth is sloped and then has a straight drop. As the dog rides up and over the peak, the prop shaft will move aft (to the rear) slightly and once over the peak, the spring will push the shaft back towards the front (fore). This is why you have the ratcheting cw and locking ccw in F gear.

In N the cam is in the mid position and the clutch dog is positioned between F and R, touching neither and the prop can spin freely.

In R, I have seen two types of shifters: One is like the F gear with the sawtooth and the other is a rectangular cog and slot arrangement where once fully engaged in R it turns neither direction.....caution here. If your system is the cog and slot, don't force the shifter in R if the engine is not turning as you can damage the linkage. Have someone rotate the prop slowly as you apply slight pressure to the shifter and when all lines up, the shifter will move on into the full R position.
--------------------

So, now that you understand the system, run this test: Put the shifter in R and see if you can stand on the prop in both directions if cog and tooth. If you can your problem is between the front of the clutch dog and the rear of F gear. Having restored a Mercruiser outdrive, the gear is flame hardened and probably not your culprit. The teeth on the front of the clutch dog may be the problem.

For the next step a manual is helpful and Seloc manuals are for sale on here via paper, or internet access. I have used the instant internet access (once you whip out your credit card and it's very reasonable) and like it as much or more than my Merc. OEM.

Pulling the clutch dog is not that big of a deal. You pull the prop and then the rear carrier assembly which contains R gear, bearing, and seals (uses 2 back to back). With the prop shaft unsupported at the rear, you can fish the prop shaft out from under the drive gear on the drive shaft and pull it free. A quick inspection will tell you what you want to know. Be sure to inspect the pin that connects the dog to the prop shaft and ensure it's ok. If you disassemble the thing the pin comes out first and then every thing falls apart. The pin is spring loaded and behind the spring are/maybe 3 ball bearings. They need to go back in when finishing up.

For the above procedure, the outdrive and LU can remain attached to the boat.
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However, before you do any of that, check your linkage: Using your remote control, put your shifter in F gear and give it some throttle (position, engine off) to ensure you are in as far as you can go, and go back to the shifting linkage at the engine/outdrive and without moving anything, disconnect the cable from the actual shifting mechanism. With the remote cable removed, see if you can advance the shifter more than it is currently advanced.

If you can, you may have nothing wrong in the LU. The problem may be that you don't fully engage F gear due to mal adjusted linkage. Adjust the linkage and be on your way.

Mark