Alpha 1 lower unit clutch dog problem?

[boatsnbeats]

I heard a clunk the other day while towing a tube with my 1988 twin Merc 5.7 Cruisers Inc. It wil no longer stay in gear with the engine running. I had the boat pulled out and tried to manually shift with the engine at idle but the prop would only nudge barely when shifting. I can get it to lock with the engine off and turning it manually in forward and reverse but in forward gear I can force it passed one "stop" before it locks. I then drained the lube and found a fair amount of paste and flakes on the drain plug. I had some of this when I drained it in the spring but I have only been out about 4 times this year. I am now guessing it is a worn or broken clutch dog and have heard that the expense to rebuild is more than the cost of a new lower unit from sterndrive engineering. How can I know for sure that it is the lower unit and is it ok to just replace the lower and not the upper unit? I looked in the top cover before I drained the lube and the upper drive gears look like new. There is only 275 hours on the motors. Any other ideas? Thanks everyone. This forum has saved me a lot.
Eric

 

[zbnutcase]

Re: Alpha 1 lower unit clutch dog problem?

With what you found on drain plug, chances are something did happen in there, and only way to see how bad it is is to tear it down! But usually it is cheaper to buy a new one from SEI.

 

[boatsnbeats]

Re: Alpha 1 lower unit clutch dog problem?

Would it make sense to just remove the lower unit from the starboard drive and put it on the port side that is in question, add lube and test it under power to test my theory of a lower unit problem? I am assuming that the drives are identical. They are not counter rotatating. I would then just buy a new drive for the starboard if my theory proves correct. For the cost of an extra quart of lune and some time I could put my mind at ease that the port lower unit really is the issue. It is ok to shift the drives into gear at least at idle while it is out of the water correct? I of course have water running to the engine and check that it is coming out the exhaust and from the prop hub.