Mercruiser sterndrive won't go in gear ++

New boat (to me) about 2 miles since I've owned it. First I/O.
1979 Mercruiser 470. Took off from ramp this evening, about 2 miles upriver, a noise, kind of like a clicking, then all forward motion stopped.
Wife not impressed with new boat.
Engine starts fine, but when I put it into gear, it alternately stalls immediately or revs up like it is disengaged with cold start button. No noises from drive unit. Seems to not be engaging sterndrive at all. When I was messing with it, motor seemed to be heating up, like *possibly* impeller is not working.
On the trailer (motor off) in neutral prop spins freely. In forward and reverse prop will not turn by hand.
Just bought the boat Saturday, and manual I ordered not here yet.
Possible problem with interrupter switch or controller/cable?
New to I/Os, but a decent mechanic. Any and all help or suggestions appreciated.
Thanks,
Greg
mbjeeper@aol.com

 

I had a busy afternoon.
I checked the cables and interrupter switch and everything seemed OK. I pulled the top cover and found a stripped ring & pinion.
I pulled the unit off and separated the halves, and it feels like there is an additional problem with the prop shaft, too. I suspect that it locked up and caused the R&P problem. I haven't been able to get the spanner nut behind the prop loose yet, so I haven't gotten a look at the lower half yet, but it doesn't look or feel good.
If I try to rebuild this unit, what special tools do I really have to have? I have set up some auto R&Ps before with good results, and I might tackle this. Estimate cost? More economical to go with another unit?
If I decide to get a used or rebuilt unit, where is the best place to go and how much should I expect to spend?
I was told that this unit has a 2:1 ratio, and is not original to the boat. How can I verify this, or identify the unit? There are no numbers visible, and the decal is illegible.
I think that this is a pre alpha (type 1?) drive. It has a ligting eye on the cover plate.
Any suggestions appreciated.
Greg
mbjeeper@aol.com

 

I would look for a good used alpha 1 drive. sounds like you have opened a bees nest.In my experiance the older drives cost more to rebuild than there are worth. Find a drive that came out of a 3.0 litre motor with a 1.8 and higher drive ratio. They usually have less wear due to the lower power used.

 

As it stands now, the lower unit is fine I was ignorant of how it shifted, but once I figured it out, I determined that it is good. I will reseal it and reuse it. The bellows are good, the shaft and joints are good, so I now need a good used/rebuilt upper unit. The tooth count on my existing upper was 24/24, which is a 1.65 ratio. Not the 2.0 as I was told. The boat should have originally had a 1.84 ratio, according to what I have read online.
I have 2 new props, a Michigan Wheel 14.5x17 (was on the boat) and a Quicksilver #48-16440-16 (spare). I would like to be able to reuse one of them, so does this mean I need to stick to the 1.65 ratio?
Now, what can I get to replace my upper unit? Will an Alpha bolt onto my gimbal and lower unit and be compatible with my shift cable?
I have heard that any '83 or older upper will work, but I do not know if this is true. R, MR, Alpha, Gen 1, Gen 2. It is all kind of confusing.
My question is, what is compatible with my needs? I need to reuse my gimbal and lower unit and shift cable, and replace only the upper unit. I see Alpha uppers for sale online, but I don't know if they will fit.
My props probably restrict me to the ratio I had (1.65), but if they don't, I will try another ratio. I really don't know anything about prop selection, but as I just bought this boat, money is an issue, and I really don't want to replace a prop if I don't need to.
Any and all help appreciated.
Greg
mbjeeper@aol.com

 

Go to sterndrives .com they would be able to help you and theres lots of stuff there to read,good luck john