Squealing noise and smoke

"I have a mercruiser 120/140 h

"I have a mercruiser 120/140 hp. motor with an alpha 1 stern drive. I had the boat on the water when I heard a noise I never heard before. The next thing I know, there is smoke coming from the bilge. It appeared to be coming from a belt of some kind on the back side of the motor. It was smoking. It appeared to be some kind of serpentine belt I think. I think it smoked when I was in gear but I'm not quite sure. Can someone tell me what this belt is and what the problem may be? I can't find info on it anywhere.
On the front of the motor I have a V-belt driving the alternator and water pump but I can't figure out what this belt-like thing is on the back side of the motor that was smoking."

Bad drive coupler.

Bad drive coupler.

Thanks Paul. I was going nuts

Thanks Paul. I was going nuts trying to find out what this thing was. Can you tell me what may have caused it to go bad? The boat is a 1985. I did have a lot of people on board at the time. Did this put too much stress on it? Or did something happen to the lower unit to put extra stress on it? Or do these just go bad on their own due to age?

"Most likely just aged and dry

"Most likely just aged and dry rotted. You have to remove out drive to replace, Good time to check bellows, gimble bearing, shift cable and check drive for cause of failure."

Does the engine have to be rem

Does the engine have to be removed at all? It's a 4 cylinder mercruiser 120/140.

"No, But depending on how your

"No, But depending on how your boat's engine compartment is set up it may be hard to get to.
You might be cursing a little before youe done, But not as much as if you took it to the shop.

Boating is more fun when it's cheeper."

You're absolutely right.

You're absolutely right. And thanks for all your help. You're as much of a lifesaver as the sheriff who toed me in when I broke down.

You may get lucky and replace

You may get lucky and replace the coupler with engine in the boat but it is highly unlikely. Especially if is a later model with the triangle coupler. A 3.0L is Pretty easy to remove. (takes me about 20 min). This will give you the opportunity to check every thing out. Might want to pull the starter bolts and coat them with anti sieze they can be a bear to change in the boat if rusty.

"It looks like the wineglass t

"It looks like the wineglass type, not the triangular one. I looked down the back of the engine and could see about one half inch of it. It doesn't look like the triangular one. Before this happened, I was going to change the transom bellows and stuff, now I can do it all together, since the drive unit has to come out anyway."