Intermittent no propulsion...

[JLorditch]

I have an 83 Chris Craft with twin 260 hp engines and Alpha drives. One day on the river with the boat, after a couple hours of riding, the boat suddenly would barely move, and the left drive seemed to be in neutral. I put it on the trailer, came home and hooked the ears to it, and everything seemed to be fine. So I took it to the lake and ran it all week long, putting 45 hours on the boat with no problems. The following weekend (last weekend) I went back to the river, and after about an hour of riding it did the same thing. It just loses all propulsion from the left drive. In trying to limp back to the dock, the right side drive suddenly did the same. I had to be towed in. When I came home and put the ears on again, everything seems to be working fine. Any ideas?

[CDK]

The combination of 260 hp, Alpha drive and 25 years old offers lots of possibilities to lose propulsion.
Has it been properly maintained all those years? Do you have Merc oil monitors or regularly check the oil condition manually?

In my opinion it is long past bedtime for the drives. I exchanged mine twice after 10 years service, then turned away from Alpha's altogether.

Some possibilities:

Rubber couplings in the props have been slipping. If this happened once, due to heavy load or wrong drive position (too far out), they need to be replaced.

Clutches in the lower housing worn.

Too much play in the shift cables.

Engine couplers lost their teeth from corrosion (alu on steel).

[JLorditch]

The boat is fairly new to me. I bought it in March. Howver, I have thousands in receipts to show the maintenance. The oil does seem to be in good shape. No metal or water intrusion. I did smell rubber burning on the right side when I was coming back on just the left motor. I think I may have overloaded it, or pushed it too hard. I am certain the coupler needs to be replaced on that side. Now I have to check the right side, Thanks for the suggestions

[JLorditch]

Correction_ coming back on just the right motor**