Lower Unit Fell Off

I have a 1997 Mercury 2 stroke 115 HP engine on my boat. While out the other day fishing, I went to start the engine to head back in and found that the lower unit had fallen off the engine and sank to the bottom. I have had this engine maintained every spring and fall by certified Mercury mechanics. The mechanics said that it wasn't due to improper maintenance but that this happens sometimes. What could be the reason that the lower unit would just fall off the engine?

Re: Lower Unit Fell Off

Two things: 1) you hit something or 2) all of the mounting hardware came loose allowing it to drop off. It is not the job of the service tech to check every nut bolt and screw on your engine while doing routine maintenance. Had the engine had a recent water pump replacement or other service work that required removal of the lower unit, I could see where the hardware could have been left loose (tech was interrupted by something or someone). Vibration could then shake things loose. However, I seriously doubt that was the case. Someone pulling a cruel prank on you is a distinct possibility as well. Someone attempting to steal the lower unit but failed to get the job done is also a possibility.

Re: Lower Unit Fell Off

Same thing happend to me.
It was less than a second after i hit a rock.

If you know where it is see if you can find a diver that could tie a rope on it for ya.



mine was not worth the bother since there was oil coming to the surface.

Re: Lower Unit Fell Off

Reminds me of the time a friend of mine left his boat in the water at a rental cottage for a week. Came back the next weekend, started the motor up (1990s 225 Johnson) and it sounded a bit loud, but didn't think anything of it. Untied the boat and went to back out of the slip. Nothing happened. Looked back at the motor and noted that the lower unit was gone and the bolts and trim tab were neatly placed in the motor well. Also found his in-boat tool box open and the wrenches in the well. The $800 stainless prop was gone, too...
- Scott