"Dogs" on 69 500 Trim?

[tredragon]

So most of my problems of late have been solved (stuck in gear... fixed... bogs under load in gear on water... carbs tuned... great...)...

However, yesterday on the water while trying to back off trailer (my trailer tilt cable is busted and pin is froze)... and also a few times while trying to adjust by reversing hard... the unit rose up out of the water then banged back down. I see the "dogs" (I'm borrowing a term from Deadliest Catch...) that kinda overlap the tilt pin on my unit... I see that they'd do a great job keeping the motor off the transom in forward... however, they are spring loaded and seem to run to a shaft that runs downward towards the LU... Are these dogs supposed to lock onto the trim shaft/pin at some point so avoid the unit from raising up out of the water? If so... what do I need to do to get them working? I essentially have nothing but very low RPM reverse without the unit flying up out of the water.

 

[tredragon]

Re: "Dogs" on 69 500 Trim?

Ahhh-choo! oops. sorry, sneezed and didn't mean to post again... ;-)

 

[emckelvy]

Re: "Dogs" on 69 500 Trim?

Actually the tilt lock is supposed to be released in Fwd gear, and lock down in Neutral and Reverse.

The reason it locks in Neutral, suppose you were flying along at a good clip and 'chopped' the throttle back to Neutral. The lower unit and prop create so much drag that the motor kicks up, unless the hooks lock it down.

And you already had a practical demonstration of why the motor needs to locked down in reverse!!

The shift cam doesn't, as you might think, push on the reverse lockout rod to force the latch hooks to lock in place. The latch hooks are made so that when the motor is tilted down, the hooks slide down on the tilt pin and wrap around the pin.

You'll note that the lockout rod moves upwards when the hooks are on the tilt pin. In Forward gear, the shift cam is not preventing the lockout rod from going downwards, so when the motor is tilted up the hooks release from the tilt pin.

When the gearshift is placed in Neutral or Reverse, the shift cam 'blocks' the lockout rod, keeping the spring-loaded hooks from moving off the tilt pin. This locks the motor down good 'n' tight.

You probably noticed the shift cam when you had the lower unit apart for impeller service. It's that black plastic piece that has a splined hole in it so it slips right down on the shift shaft.

There's a ramp built into the cam and the position of this ramp determines whether the hooks will lock down or release when you tilt up the motor.

The correct placement of this cam is such that, when the lower unit is just about to shift into Neutral (but is still in Fwd), the end of the lockout rod is pointing to a spot about halfway up the ramp. If you look at this while it's apart, it'll be obvious.

I know that you'd typically put the lower unit in Neutral when installing, that's no problem. Just shift it to Fwd, get the shift cam set up correctly and then shift the lower unit to Neutral before you reinstall.

The cam can only go on one way and work correctly. If it's off by one tooth in each direction, you'll know because it's no way even close to being aligned with the reverse lockout rod.

Underneath the shift cam is a plastic thrust washer with some tabs on its sides. This fits with the smooth part up. It's a good idea to grease this area, and the shift cam ramp, with some waterproof grease. Just be sure that if you get any grease on the top of the shift shaft to wipe it off. Grease on top will "hydro-lock" the shift shaft and shift rod when you try and put them together. NOTE: if this washer is missing, the lock may not work correctly.

Another problem occurs when the hooks are not free to pivot, in that case some PB Blaster on the pivot points and maybe a little heat if necessary, will help loosen them up.

With the motor tilted up, clamp on a pair of Vise Grips for leverage and you can work the hooks back and forth until they free up.

Last thing, if your plastic cam is worn, the lockout may not work. Merc sells a metal replacement that's much more durable.

OK, this concludes Reverse Latch 101, now it's time for the Practical Application portion of this program!..........ed

 

[tredragon]

Re: "Dogs" on 69 500 Trim?

hmmmm, so when I had to move the shift shaft to get the lower unit into neutral (remembering back to when I had improperly reinstalled the LU and was stuck in forward for an outing).... anyways... when I had the LU off and was playing with the shift shaft, on the base of the shaft (bottom) was the plastic cam. I wasn't sure it made a difference but apparently it does. The hooks move, so they aren't froze. I'm guessing that after I pull the LU... I'll move the cam as if I was "screwing it in"... to bring the higher part of the rise to the lockout shaft.

I knew it had something to do with the shifting of gears as soon as I saw the rod running down to the lower unit. Now I'm wondering how to know when I have the cam in just the right place before putting the LU back on. I guess I can do like you said. shift just into forward and look for the lockout rod to be pointing about halfway up. Then I'll put the LU back on (shifting back into neutral first) without completely tightening everything down all the way, and check the operation of the hooks.

I still like calling them dogs though :-D

 

[tredragon]

Re: "Dogs" on 69 500 Trim?

worst case, if it was locked all the time except deep into forward... at least the flying motor syndrome would be alleviated and all I'd have to do to tilt the motor is to shift into forward a ways (killing the motor first! :O )

 

[tredragon]

Re: "Dogs" on 69 500 Trim?

hmmm, or is the motor supposed to have some play while in forward as the plane changes?

 

[emckelvy]

Re: "Dogs" on 69 500 Trim?

These Mercs are designed to only be able to tilt up when the gearshift is in Forward. What I do when coming into shore is when you're ready to kill the engine and tilt up, just turn the key to "Off", leaving the gearshift in Fwd.

Leave it in Fwd until you're ready to tilt back down and you'll never have an issue with setting the motor back down on the pin with it in Neutral, which will jam up the hooks and make it hard to shift.