Reverse engine lock won't hold on vintage Mercruiser IO 153 cu.in. 120 hp engine

[redgoat]

There is a spring loaded lever on my outdrive that is identified as "Lock" and "Unlocked" designed to keep outdrive locked down when operating in reverse. My outdrive will release and raise up in the water when engine is put into reverse even though lever is in the locked position. Is there any way to keep this from happening on my 55 year-old Mercruiser?

 

[Bondo]

Ayuh,..... Can you Id the drive,..?? It don't sound like it's an MC-1,.....

 

[redgoat]

Bought this 17' Sea Ray brand new in 1967 and I can assure you that it is a genuine Mercruiser engine. The engine serial number is 2050478 and the stern drive unit serial number is 2069523. Boat is currently is in storage for winter so the best photos I have to show are attached.

 

[kenny nunez]

If your boat still has the 1 hydraulic line going to the rams there is no way for the hydraulic system to hold the drive down. The “corkscrew” shaped brass shift lever below the bell housing is supposed to keep the lock mechanism engaged on the setting pin. Is the lever on the side of the bell housing working correctly?

 

[Scott06]

Ayuh,..... Can you Id the drive,..?? It don't sound like it's an MC-1,.....

I belive it is a 1A, 1B, 1C EZ drive. They made them 1965-68. they were replaced by the MC-1, have a hook on top like an MC-1 but have only tilt not trim with one hyd line per cylinder. Also had separate lube reservoirs for upper and lower...

Amazing the OP still has it in working order, my grandfather had one on his 1966 Penn Yan, which I helped him maintain in my teens...

 

[Scott06]

There is a spring loaded lever on my outdrive that is identified as "Lock" and "Unlocked" designed to keep outdrive locked down when operating in reverse. My outdrive will release and raise up in the water when engine is put into reverse even though lever is in the locked position. Is there any way to keep this from happening on my 55 year-old Mercruiser?

Like the tow vehicle ... sorry cant help much with your issue.

 

[matt167]

My dad has one still in service as well although he retrofitted an MC1 style lower on and uses a chain for reverse. Its a Fishing boat so good enough but wouldn’t work for a boat as nice as that.

I think changing to an alpha gen one is what that boat deserves. It shouldn’t need much to make it work

 

[redgoat]

If your boat still has the 1 hydraulic line going to the rams there is no way for the hydraulic system to hold the drive down. The “corkscrew” shaped brass shift lever below the bell housing is supposed to keep the lock mechanism engaged on the setting pin. Is the lever on the side of the bell housing working correctly?

There are two hydraulic lines going to the outdrive to tilt it--one line on each side of the outdrive. Unlike newer outdrives, this mercruiser outdrive only has a "tilt" capability for shallow water and for trailing. There is no "trim" capability like newer models. When this boat was new, I could move in reverse at a fairly low speed w/o the engine raising up. Using reverse w/o the engine raising up makes it easier to approach the dock. Could the spring that is supposed to hold the rod to the outdrive be weak? I know when I move the lever from locked to unlocked position there is a definite "click."

 

[kenny nunez]

That is probably what is wrong. With the drive lifted about 1/2 way have someone shift the drive into reverse and watch the mechanism. The spring may still be available but to change it takes some work. Upgrading to a later drive platform would be the best way to go. You will need everything from the rear of the engine back if you want to change to the Alpha system.

 

[Bt Doctur]

I actually have one of those locking devices, if I can locate it ,I`ll pm you

 

[ROY WILLIAMS]

There is a spring loaded lever on my outdrive that is identified as "Lock" and "Unlocked" designed to keep outdrive locked down when operating in reverse. My outdrive will release and raise up in the water when engine is put into reverse even though lever is in the locked position. Is there any way to keep this from happening on my 55 year-old Mercruiser?

you have to troubleshoot the outdrive up/down ... electrical or the cylinder ..
https://www.marineengine.com/parts/mercruiser-sterndrive-parts/120140-19671969/2062141-thru-2791956