motor runs like butter, prop wont spin

[breakingbass]

hi all, im new to the forum, and relatively new to boating. i have a 1986 omc stern drive with a 3.0L 4-cyl motor mated to it on a 1986 galaxie v-hull boat. the boat has been running great, i have had zero problems with it, it was well taken care of, and since ive owned it i have been keeping up with all fo the maintenance, fluids, washing, cleaning, and flushing the motor after every trip.

my first problem occurred over this past weekend when about 5 miles out from the boat launch, i lost drive to my propeller. the motor was still running like normal, but giving it throttle would just make the motor rev high before it would eventually die. the motor still sounds and runs good, i just cant get any power to the prop. i own the service manual for the boat, and have been reading it since before this problem occurred and from what i gather, my guess is that i either have a problem with the shift cable, or something in the lower part of the drive such as the prop shaft, clutch, or some other type of shaft has broke.

when the motor is off, the prop is not seized, it spins freely and normally, and the motor still runs fine. my buddies are coming over tomorrow to help me diagnose, isolate and repair the problem. can anyone shed some light on this problem? is this a common problem? im guessing i should start with looking over the shift cable and then going to the lower out drive!?

i have also read conflicting posts about whether it is neccessary to remove the entire outdrive from the boat to be able to open up the lower out drive. is this accurate? can it be donw while still attached to the boat?

any help with this would be really really appreciated. if there are any more questions is can answer about my problem that might help shed more light, please fire away. thanks again!

 

[jerryjerry05]

It sounds like the props hub has spun.
remove the prop.Take a marker and make some lines on the inside of the hub.
Reinstall and go for a ride.
Then when it slips remove the prop and check the marked lines.
If they moved? Then it's a bad hub.
If they stayed in place.
Then the coupler on the motor might have spun.
Same thing as the prop it has a rubber hub that can slip/ spin.

Just hope and pray it's the prop. The coupler requires a motor removal.

 

[southkogs]

Welcome aboard.

'86 should be a Stringer, and I would suggest it's easier to remove the entire drive. However, it's not necessary to take the whole thing off to remove the lower unit. The mechanical shift takes a little longer, but I know my ES comes off in about 10 minutes. I can't imagine it takes more than 20 minutes to get a mechanical drive off.

I like Jerry's idea of lookin' at the prop hub first though. Do you happen to have a spare?

 

[breakingbass]

i pulled the prop exposing the shaft, i hooked up the ear muffs to the out drive and started her up in my driveway. i tried to give it a little throttle to see if the shaft would spin, but it didnt. the motor just revved high with no spin to the shaft. as soon as i get home today im going to examine the shift cable and see if i have some sort of break or severe. thanks for your reply, if you can think of anything else i should be looking into, please fire away. thanks again.

 

[vinnie1234]

Your best bet is to remove the lower, but before you do, take 5 minutes and check the shift cables up at the intermediate housing to ensure they are intact. Removing the lower isnt hard and it does not require outdrive removal. it is actually easier if you leave the upper in place.
First, make sure you get all of the bolts out. I think 4 bolts around the perimeter, you will have to remove the fin on the cavitation plate (one more mark it's position too) and then there is a large bolt (anode) up above the fin. ^ in total? Don't take my word for it. look hard and pull them all.
Tilt the drive up, but not all of the way. Get a couple of sawhorses nearby. The lower gearcase should pull off straight down from the upper. Be gentle, don't use a pry bar unless you are VERY gentle. If It has troubles coming loose, you can tap it GENTLE with a dead blow mallet. If it still doesn't come loose - you missed a bolt - look again.

Once you have it loose, set it up on the sawhorses. there is some play in the shift cable coming out of the upper, so you can actually pull it through the upper a bit to give yourself some room to work from the back. There is a molding on the cable to help it stay in place. If you do pull it out, make sure it goes back the way it came out.
Now go to the helm and shift into gear. Spin the prop to see the rotation of the input shaft on top of the lower. Works? Repeat for neutral and reverse. If it doesn't work, you will have to remove the shift cable housing and manually move the shifter rod to confirm. If it does work, move over to the upper gearcase. Does the driveshaft spin there? If so, check the ball gear. When I got mine it was finger tight. I had to fix that straight up.

 

[breakingbass]

UPDATE: my buddies and I went to work on the outdrive this evening and here are our findings:

-we inspected the shift cable and it was all good except for a slight tear in the jack right before the cable goes through the fiberglass and into the outboard

-we removed the lower housing with no problem. the prop is off, and when we pull on the shift rod and turn the propeller shaft, we can see the spindle on the other side turning as well. we tried this in reverse by pushing down on the shift rod and it also spun on both sides. can i rule out the lower gear case as containing the problem? i would like to open it up eventually and do a full service by replacing all of the seals and gaskets, but if i can spin the prop shaft by hand and see the other spindle opposite the prop shaft, is it safe to say that the problem does not reside in the lower housing?

-when we first got back to my driveway after the breakdown, we were running water through the muffs and trying to see if the shaft would spin while the propeller was off. it kind of lazily spun just a bit. when the outdrive was tilted up, my buddy noticed that the ball gear coming from the engine was spinning. when we lowred the tilt to engage the outdrive, there was no power making it to the prop shaft. we now believe that the issue lives somewhere in the intermediate housng.

-is it possible for the shaft that the ball gear that lives on the outdrive to snap, or some other problem of this same nature?

-we believe we may have cornered our culprit to somewhere in the intermediate housing. we ran out of day light, but will be back out there again later this week. thanks for all of the info guys, it came in real handy. any more thoughts on this thread are very welcome, thank again!

 

[breakingbass]

UPDATE:

we were able to remove the intermediate housing from the boat and have confirmed that the failure is the shaft within the housing. i am currently looking for a place to find a replacement part, and new seal kits for both the lower and intermediate housing. ill post pics in the morning.