Spun Hub question 115 Evinrude 1975

[markh28]

1975 Evinrude 115HP Model 115593

I have the factory service manual for this motor but can not find a torque spec for the prop nut. I am trying to figure out why I spun a hub. Could a "too loose" prop nut cause this? The cotter pin was present but the prop nut was finger tight.

So then I bought a used prop from a boat dealer. He said it was a good (not spun) prop. I tightened the prop nut finger tight, then advanced it with a wrench until the next available cotter pin hole in the castle nut (about 1/8th of a turn). Took it to the lake, same exact behavior. It revved up and went nowhere, but worked at idle and in reverse.

I am trying to rule out why I am spinning these hubs. I am certain I am not hitting anything with them, since I didnt even get 20ft off the dock, and I used 2 different ramps at different locations on the lake. The second hub may have been bad, I have no way of telling other than the dealers word that it was good. Will improper torque on the prop nut cause the hubs to spin out?

Frustrating problem since I can not test it in my driveway on the muffs and the nearest lake is 50 miles away. Any ideas are appreciated.

 

[Bosunsmate]

Are you sure its not the forward gear thats gone? Is it actually selecting forward gear? You can test that with motor off, check the prop shaft doesnt turn when in forward gear with control box
The shafts splined so nut torque shouldnt really make much difference, i do it roughly in the same manner as you, but i do make sure its snug.

 

[fireman57]

Yep. Sounds like it's time to rebuild a lower unit. Had the exact thing happen on a 48special last year.

 

[emdsapmgr]

Put a mark on the brass inner sleeve (hub) of the prop and the outside rim of the prop. Go boating. When you pull the boat out of the water check the two marks on the prop. If the alignment of the two marks has changed position while running, then the prop has a spun hub. If not, the problem is not with the propeller.

 

[markh28]

I will check to see if I can spin the prop with the motor off and in forward. Come to think of it, this problem started after I pulled the lower unit to adjust the shift rod height. My motor wasn't returning to neutral correctly so I had to pull the lower and unhook the shift linkages. Possible I didnt get it back together correctly or its binding up on me and not fully going into gear. I will post back results.

 

[markh28]

Maybe I am jumping the gun here a little bit but I want to know what I am up against. I adjusted my shift linkage a little and put some marks on my shaft and prop to determine if I have a spun hub. Going to make the 90 mile round trip to the lake and test it out.

If my prop doesnt have a spun hub and I still cant go anywhere in forward fast, I am going with the notion that my forward gear is shelled.

In that case, what am I looking for when I open the lower and pull it apart? Will I know just by looking in there what is shot? Will the gears and/or clutch dog be obviously shelled out? With these parts (or a new lower) being pricey, I just dont want to go replacing a bunch of stuff needlessly.

 

[F_R]

If it is the forward gear or dog, or adjustment, it would be noisy/grinding sound. Repair will cost big bucks. Let's hope it is the hub. BTW, it is totally impossible to test for a slipping hub by trying to rotate it with the motor not running. Well, that is impossible unless you are as strong as 115 horses, which I seriously doubt.

 

[markh28]

Its definitely not making a grinding noise, or any other abnormal noise other than the normal exhaust sounds. Interesting what you say about trying to rotate the the prop with the motor off...I was running the motor on the muffs in forward gear, I revved the throttle higher and at the same time turned off the key. I did this so I could have my motor in forward gear and turned off. (With the hydraulic assist, I cannot shift gears while the motor is off) I then went and attempted to turn the prop. The prop was really hard to turn, but did turn about 1/4 turn each try, and the prop shaft and flywheel turned with it. And each time I turned it I could hear rubber squeak. However, the prop shaft and flywheel still turned with the prop. Is this behavior normal?

 

[Bosunsmate]

a squeak shouldnt happen unless you a getting movement

 

[Bosunsmate]

id mark the hub as mentioned above

 

[glenn property of pam]

Its definitely not making a grinding noise, or any other abnormal noise other than the normal exhaust sounds. Interesting what you say about trying to rotate the the prop with the motor off...I was running the motor on the muffs in forward gear, I revved the throttle higher and at the same time turned off the key. I did this so I could have my motor in forward gear and turned off. (With the hydraulic assist, I cannot shift gears while the motor is off) I then went and attempted to turn the prop. The prop was really hard to turn, but did turn about 1/4 turn each try, and the prop shaft and flywheel turned with it. And each time I turned it I could hear rubber squeak. However, the prop shaft and flywheel still turned with the prop. Is this behavior normal?

in gear the water pump is turning so a squeak is normal. Also the prop turning a little is normal. I have a prop that is sometimes spun. It will sometimes let go just as the engine starts to reach max power and the boat isn't on plane so I guess it can handle 90% of the engine torque before it slips. Only way to tell was with a paint marker as it seems to self heal and only happen now and then.

 

[Bosunsmate]

Yes good point about squeak and pump^

 

[markh28]

Yes, the impeller and housing are brand new so that makes some sense.

 

[glenn property of pam]

back to the original post. Do you fish in weeds or shallow grassy water. The reason I ask is I spun 2 props my first month on the lake before I learned to reverse before trying to go on plane as that clears the weeds off the prop. sometimes even that doesn't remove the weeds so you have to trim the motor up and clear the prop by hand.