Reverse lock not working

[383cross]

This weekend when i tried to back the boat up in the water the motor reared up towards the boat then slammed down as i got off the throttle. I checked the locks on the trim bar and they are present but they dont work, the shaft that comes from the lock to the lower case of the motor doest feel attached to anything. Anyone know how to get in there and see what's broke or disconnected? The motor is a 1976 Merc 65hp outboard.

 

[Yepblaze]

Re: Reverse lock not working

The rod that goes into the lower unit rides on a cam, or ramp arrangement.


If the cam is missing it might cause problems.

But.....
On some of the motors this cam arrangement only releases the hook for forward operation. And because of this I have seen the adjustment available at the hooks adjusted to disable this feature all together.

So watch the rod and see if it goes up and down when run through the gears. (that might indicate that the cam is still in place) and if so adjust the mechanism.

If the rod doesn't move, drop lower and look for cam.

 

[383cross]

Re: Reverse lock not working

I just checked and the rod isnt hooked to anything in the lower, and it doesnt move when in any gear or nuetral. so how do I drop the lower? I didnt see any bolt points anywhere, are the bolts inside the engine cover somewhere, I havent pulled the cover off to look yet but I'm assuming thats where its bolted up. Any help would be appreciated.

 

[emckelvy]

Re: Reverse lock not working

Silly question, when you lower the motor down do you have the gearshift in FWD? Because if you have it in Neutral you will lower the motor's tilt pin right onto the reverse lockout hooks. Merc's are typically designed to lock not only in Reverse but Neutral too.

It's possible someone put the shift lock cam on wrong, but first I'd check to make sure the motor is properly resting with the tilt pin "nestled" into the lockout hooks. Not with the tilt pin on top of the hooks.

The way this really works is, when you put the motor into the hooks, the way they're cut allows them to wrap around the tilt pin.

If the motor's in Fwd, the shift cam does not block them from moving and they will just slide along the tilt pin.

If the motor is in Neutral or Reverse, the shift cam moves to block the downward motion of the lockout rod. So, the hooks cannot slide off the tilt pin, and remain positively engaged.

This is actually backwards from the way you'd think it works. The shift cam does not "push" the locks open or shut. It only allows them to open, or blocks movement.

So give that a shot and see what happens. If your motor won't lock in Neutral or Reverse, you'll probably want to pull the lower unit down for inspection of the shift cam...........ed

 

[383cross]

Re: Reverse lock not working

The hooks definately dont ever lock around the pin reguardless of the gear, drive, nuetral or reverse, in any gear you can grab the hook rod and move the hooks freely so it cant be engaging with anything in the lower case, looks like i'll have to figure out how to remove it and get it working.

 

[Chris1956]

Re: Reverse lock not working

There is usually a spring to pull the hooks down. Is your intact? There is also a locknut on an adjustment of the hook. See if you can adjust it.

Finally, Don't hit the power in reverse too hard, and you may not need the lock.

 

[383cross]

Re: Reverse lock not working

Where's the spring located at? I havent seen any spring anywhere but i'll look again, maybe i can figure a way to spring it until winter when i can tear it apart and fix it right (hate to rig anything). I do know that i can unhook it or hook it and the rod is loose at the bottom so I dont think it's attached to anything.

 

[Chris1956]

Re: Reverse lock not working

OK - Get on the Crowleymarine.com web site and look up the exploded parts diagram fro your motor. Look on the "Clamp and swivel bracket Assembly" page for item 37. This is the spring for the reverse lock out mechanism.

 

[383cross]

Re: Reverse lock not working

Thanks, I'll check it out today

 

[emckelvy]

Re: Reverse lock not working

The spring makes sure that there's tension on the reverse lock but that wouldn't keep the lock from working in Neutral or Reverse. Still think you're gonna need to pull the lower unit and check out the reverse lock cam.

Note that the reverse lock rod does not connect to anything on the bottom. It's free to move up and down. The fact that its movement is not restricted/blocked by the shift cam is a clue to the problem. Either that or someone's got the adjustment so far out of whack that it won't work.

But that's an adjustment rarely messed with, more likely a problem with the shift cam.

Here's another place with diagrams:

http://www.mercruiserparts.com/Show...65&bnbr=17&bdesc=DRIVE+SHAFT+HOUSING+ASSEMBLY

 

[Moody Blue]

Re: Reverse lock not working

Have one lower unit in my shop where the shift lock rod was so badly corroded on the end that it chewed up the shift cam to the point it no longer raised or lowered the shift rod enough to engage the locks. Could be a possibility with yours.

 

[383cross]

Re: Reverse lock not working

I agree it looks like i'll have to pull the lower, visually everything is in place upon examination of the outside, spring is in place, locks around the rod fine but obviously wont keep motor from rocking up in reverse. Anyone have any tips on pulling the lower, any info would be greatly apreciated.

 

[Yepblaze]

Re: Reverse lock not working

There's probably a bolt up under the trim tab. But the trim tab is removed from above with a long allen wrench.

I prefer to remove and replace the lower unit's with them in neutral.

As you mess with it the shiftshaft it will pop off it's neutral detent and "fall" into forward. It may take a couple few tries to get it (the lower unit) back up, and installed and still have the shift shaft aligned with the mechanism and still be in neutral.

The shift shaft may be turned with pliers, but wrap a rag or piece of leather around the splines so you don't tear them up while manipulating the shaft. They will sometimes turn full circle in one direction but not the other.

Do not lift the shift shaft up out of the lower unit as it will become dislodged and may require complete lower unit dis-assembly to correct.

 

[Chris1956]

Re: Reverse lock not working

383 - The bolt that holds the zinc anode (above and behind the prop) is likely a 1/2" hex head. You will need to use a thinwall socket, and pick the socket that just fits the hole above the zinc.

 

[Moody Blue]

Re: Reverse lock not working

from Chris1956
"The bolt that holds the zinc anode (above and behind the prop) is likely a 1/2" hex head. You will need to use a thinwall socket, and pick the socket that just fits the hole above the zinc."


Just finished working on three lower units from the early 70's. All three used a 7/16" 12point flanged bolt to hold on the trim tab. Really threw me why I couldn't find a socket to fit the damn bolt. All my regular sockets are the standard 6 point. Even tried metric sizes. Finally looked down into the hole with a flashlight and to my surprise that is what I found. Not sure if they were factory issue or not.

 

[383cross]

Re: Reverse lock not working

Thanks alot, I seen the bolt on there today and as soon as I get some free time i'm gonna pull it off an see what the deal is. I assume I have to remove the prop to be able to pull it off, anything else?

 

[Yepblaze]

Re: Reverse lock not working

No need to remove propeller that I know of.

 

[383cross]

Re: Reverse lock not working

Got it fixed! The guide was broken and it allowed the fod to jump off the cam and broke a piece of it off, locks just like it's supposed to now. But now when you put it in reverse it grinds and you can feel it in the throttle, at an idle or barely above it tries to move backward but if you give it any throttle it really grinds and doesnt move and the rpms shoot up quick. Any thoughts?

 

[emckelvy]

Re: Reverse lock not working

Check the adjustment of your shift cable. It should be adjusted so that it pushes the shift arm as far to the rear of the motor as possible, and still shifts back to Neutral properly.

Note that when you're tweaking-in this adjustment without the motor running, you may need to turn the prop a bit so it'll shift into reverse.

If you can't get the right amount of travel no matter how it's adjusted, there may be something worn in the control box.

But first, try disconnecting the shift cable and shift by hand. If it shifts OK by hand it's probably in the box. If it doesn't, there may be a problem in the lower unit.

Don't know if you could tell before whether reverse gear was working properly, with the lockout problem. If it was for sure, I'd lean towards an issue with the control box.

Something else to check is that there's no binding in the shift arm/lockout mechanism. If the lockout rod was adjusted too far down, it'd bind on the shift cam and that can also cause problems shifting to Rev.