First I/O. Made it 2 miles

[mbjeeper]

Help. I bought a 1979 Sea Ray, Mercruiser 470 last weekend. Ran fine when seller owned it, but I made it 2 miles from the launch ramp and I was throttling back once I was planed and heard a stripping-type noise, and all forward motion stopped.
Now when i start the motor and try to engage the drive, it will either stall immediately upon shifting, or rev up like the cold start button has been pressed and shifter is bypassed. About equal amounts of each.
On the trailer (after rowing out of 2 barges' way and a tow) with the engine off the prop spins freely in neutral, and when engaged in forward or reverse I cannot turn the prop by hand.
The drive makes no noise at all.
is it possible that this is an ignition interrupter or cable problem, or is it something worse? I am new to I/Os and the manual I ordered when I bought the boat is not here yet, so I'm in the dark.
Any suggestions or troubleshooting tips greatly appreciated. Thanks,
Greg
mbjeeper@aol.com

 

[Haut Medoc]

Re: First I/O. Made it 2 miles

My first suspicion would be the lower shift cable.....
What symptoms does it show while on the trailer?
While running on the muffs will it shift?....
Welcome to iboats, BTW......JK

 

[mbjeeper]

Re: First I/O. Made it 2 miles

My first suspicion would be the lower shift cable.....
What symptoms does it show while on the trailer?
While running on the muffs will it shift?....
Welcome to iboats, BTW......JK

Busy afternoon.
I took a look at the cables and everything up top looked OK, so i pulled the top cover from the drive and found problem #1; stripped ring & pinion gears.
I pulled the drive, and the lower cable looks OK. I have the upper and lower halves separated, but I haven't gotten the lower part of the unit all the way apart yet because I can't get the spanner nut from behind the prop loose, but it seems like the prop shaft has a stripped gear, too. (Probably locked up and caused the problem with the ring & pinion).

So, I am probably looking at a new (reman) drive.
This is a pre alpha (type 1?) drive. It has the little lifting eye on the top cover. I was told that the drive has a 2: 1 ratio (not the drive that came with the boat originally). How can I verify this, or identify the unit? I can find no stamped numbers, and the decal is illegible.
Where can I find a good quality reman or used drive, and what should I expect to pay?
If I try to rebuild this unit, do I really need the special Mercruiser tools for the R&P, or can I do the setup without? I have done some car rear ends with good results, and might tackle this.

 

[Haut Medoc]

Re: First I/O. Made it 2 miles

Good question....
2:1 might be the right one, but.....
Post the serial # that is on the starboard side of the engine......
That will tell you what should be on there.....
The tools & techniques needed to rebuild are costly and beyond a DIY'er, IMHO.....
In the long run you will save time & money by getting the correct bolt on replacement......JK

 

[mbjeeper]

Re: First I/O. Made it 2 miles

Update.
I finally got tthe spanner nut loose and took the lower unit apart and believe it is OK. I wasn't sure how it shifted, but I think I've got it figured out and I think now that it is OK. There was no damage to the gears or splines, and everything looked good.
I will have to replace the seals, but I believe it to be re-useable.
I am going to count the gear teeth in the upper unit tomorrow morning and determine the ratio.
Probably will try to find an Ebay used unit to replace the upper once I determine the ratio. That way I can keep and use the 2 new props that came with the boat.
Learned a lot about Mercruiser sterndrives today. Really not that complicated, but parts are costly.
Greg
mbjeeper@aol.com

 

[danthern]

Re: First I/O. Made it 2 miles

What a nice guy that sold you that one.....

 

[danthern]

Re: First I/O. Made it 2 miles

I don't mean to sound like a smarty, but I bought a small ski boat that the lower unit went out the 2nd day on the water, gears were mangled. The previous owner swore that he'd never had a moments trouble. Expensive lesson.....Good luck!

 

[mbjeeper]

Re: First I/O. Made it 2 miles

I don't mean to sound like a smarty, but I bought a small ski boat that the lower unit went out the 2nd day on the water, gears were mangled. The previous owner swore that he'd never had a moments trouble. Expensive lesson.....Good luck!

Well, yes.
I guess if I ever buy another one I'll know what I need to look at first. But it's too late for this one.
Good thing I had an oar.
Hopefully i can get it back together and salvage a little of what's left of this year.
I have found a pre alpha upper that was from a 120/140 and has a 24/20 tooth count. I read that this tooth count is a 1.81 or 1.98 gear ratio. How can it be either/or?Are the 120/140 gears any smaller (less strength ) than those for a 170 HP motor? My ratio is supposed to be either 1.81 or 1.84.
Could I user this upper unit?
Thanks,
GB
mbjeeper@aol.com

 

[Don S]

Re: First I/O. Made it 2 miles

Sure, that upper will work, but it won't work properly.
Either get the right one to start with, or get the wrong one first, go through a lot of props trying to make it work properly (which won't happen) THEN get the right one. Which way do you think will be the least expensive

 

[mbjeeper]

Re: First I/O. Made it 2 miles

Sure, that upper will work, but it won't work properly.
Either get the right one to start with, or get the wrong one first, go through a lot of props trying to make it work properly (which won't happen) THEN get the right one. Which way do you think will be the least expensive

The way I read it, it possibly has a 1.81 ratio, which is within the range that mine calls for (either 1.81 or 1.84). If this is the case, it should work. I am going to have to replace the prop anyway, as the unit that trashed itself was a 1.65 unit.
GB

 

[Don S]

Re: First I/O. Made it 2 miles

You asked a question, and you got answers. Since you seem to have already decided what you were going to do, i'm not sure why you asked the question to begin with.
Good Luck.

 

[mbjeeper]

Re: First I/O. Made it 2 miles

You asked a question, and you got answers. Since you seem to have already decided what you were going to do, i'm not sure why you asked the question to begin with.
Good Luck.

No, I was just asking if anyone knew the correct ratio for this tooth count. If it is 1.81, I can use it. If it is 1.98, then I'll pass on it and try to find a 1.81 or 1.84.
New iation I have recieved tells me that it is a 1.98 unit, so I'll probably just keep looking.