adjustment or bad dog clutch

[ILLboater]

Hi all, just found this forum today, hope you can help.
We had a new experience yesterday. As we were trying to plane at about 1800 -2000 rpm the wife and I heard and felt a double clunk. We also think we heard some type of a whirring noise, but not too sure on the noise. I stopped the boat and checked the prop, it was ok. So we tried again and the same double clunk happened. Pulled the engine cover, no weird noises or smells. Playing it safe, we putzed back and called it a day. We have an '84 merc 470 with the alpha (all original and no hourmeter). FYI, it was the same type of clunk we always get when we shift into gear. Sometimes I get the double clunk when shifting into gear. We don't plan on keeping the boat more than a another year or 2, so I don't want to sink anymore $ in it than necessary. I called around and was told it could be just an adjustment to the shift cable or the dog clutch could be on it's way out. Haven't touched it yet, looking for insite. Thanx

[Technical Support]

I would say you've gotten pretty good advise already. Either a shift cable adjustment or the clutch dog going out. I would lean more toward the clutch dog going out as the teeth are undercut, and once you are in gear it doesn't want to come out. If they are worn quite a bit, then they could slip out. If that is the case you would be looking at a new clutch and gearset. At that point I would recommend just buying a new lower from us.

Tech Support

[ILLboater]

That's what I was thinking too or possibly the whole drive. After I posted, I checked the adjustment. The shifter piece in the lower wasn't going into fwd as far as it could go. Reverse was all the way, so I adjusted the cable until fwd felt fully engaged. I also drained the lube, no water, did not smell burnt and only a very few tiny chips. Gonna try it out this sat, if it doesn't work I may be buying a drive or at least a lower from yah.

[ILLboater]

I thought the adjustment worked. Everything was fine, tried it repeatedly, worked good. Then later on in the day I got this bad knocking, thought it was a rod. Did not feel any knocking when I felt the valve cover, but put my hand on top of the drive and there it was. Tried it at home on the muffs, made a terrible bearing noise coming from the upper. Gonna pull the drive tomorrow and check it out. Any thoughts?

[Technical Support]

You can drain the oil and pull the top cover off with the drive still on the boat. If something is going on in the upper you should be able to see it.

Tech Support