'69 Merc lower unit in forward and reverse at same time?

[aeronutt29]

I pulled the lower unit off to replace the water pump impeller and couldn't remember which way to turn the shift shaft to get it into forward. I found that no matter which way the shaft was turned, the prop shaft ratcheted one way and not the other. This seemed odd to me as I expected the shaft to ratchet the opposite direction when I turned the shift shaft the opposite direction. Also, I couldn't seem to find a middle ground where the prop shaft would spin freely for neutral. In an attempt to get the shift mechanism to switch to the other direction, I applied a bit more pressure to the shift shaft and found that it will turn 360 degrees with a bit of a spring-loaded cam effect. Now, the prop shaft still ratchets one direction, but the drive shaft won't turn either direction. It clunks back and forth about 1/8 inch (about what I would expect to be taken up in gear lash) but will not rotate. My fear is that I've somehow managed to engage both the forward and reverse gears at the same time by rotating the shift shaft past where it is supposed to stop.<br /><br />Anybody have a good guess on what really happened and how to fix it? The shift mechanism worked perfectly before I messed with it.

 

[Hooty]

Re: '69 Merc lower unit in forward and reverse at same time?

I don't have a Merc manual, but looking at my 'rude manual, I don't see how it's possible for the lower unit to be in forward and reverse at the same time. <br />Take another look at your manual.<br /><br />c/6<br /><br />Hooty

 

[aeronutt29]

Re: '69 Merc lower unit in forward and reverse at same time?

<Bump> <br /><br />Anybody else ever have the drive shaft lock up with the lower unit removed?

 

[corm]

Re: '69 Merc lower unit in forward and reverse at same time?

You need to turn the shift shaft 1/2 around so that u feel some detents. The shaft will only go one way clockwise if memory serves me. the 1st detent is F gear 2nd is N. When u find N turn it back to F so when u install it u can turn the propshaft counter clockwise to mesh the driveshaft spline with the crankshaft. Make shure<br />that the motor is shifted into F gear also. If the splines on the shift shaft are messed up square them up with a small file before installing.Other wise u will break something <br />Put some grease on the outside end of the water tube and the shaft splines so it will slide together better. Also the exhaust tube if u have one in your motor.<br />...have fun...corm

 

[aeronutt29]

Re: '69 Merc lower unit in forward and reverse at same time?

Thanks for the tip on finding the detents. I got the shift shaft turned around to where I feel the detents engaging and the prop shaft turns freely in neutral, but the drive shaft is still stuck. I'm afraid to put too much pressure on it in case some little ball bearings have fallen out of place and are jammed into the gears. I've got a bad lower unit laying beside the house that I'll take apart tomorrow and try to figure out what else might have gone wrong.

 

[Walker]

Re: '69 Merc lower unit in forward and reverse at same time?

A new impellor will make the drive shaft hard to turn by hand.

 

[corm]

Re: '69 Merc lower unit in forward and reverse at same time?

Pull the waterpump off and try it. You may have pinched something or jammed the pumpkey into the base.<br />Corm

 

[aeronutt29]

Re: '69 Merc lower unit in forward and reverse at same time?

Now that I've found the problem, I think my post would be better suited for the "stupid human tricks" board. If my hand was applying 5 ft-lbs of torque, then 6 ft-lbs is what is required to overcome the oil seal stickyness. A socket with just the slightest amount of force "broke" it loose and everything works exactly as advertised.