Thinking of buying a 73 MFG with OMC sterndrive. I am told it has broken a gear in the drive system. I am assuming it is either the ball gear or #92 in the 4 cylinder (though this is an inline 6)intermediate housing illustration. Either way are these type parts still available for a 38 yr old OMC? Any obsolete parts in there to be aware of?
parts are definately hard to come by and very expensive omcs are also in my opinion poorly designed and gimmickey very highly prone to failure and not user friendly to work on or mechanic friendly for that matter
Don't know about a stern drive but I have a '66 100 horse and I've located any part I've ever needed. First thing you need is the original parts manual with the exploded views and part numbers. Do not confuse this with the shop manual.
Marine Engine . com is a good source, as is Sea Way Marine, but if you don't have the part numbers it will be much harder. Sometimes you can find it just by doing a web search for the part number. And never underestimate ebay.
But again I was dealing with an outboard, I don't know much about sterndrives.
The part that is likely worn is a kind of nub-gear that transfers power from the motor to the stern drive. When the drive in lowered, all the teeth mesh together to drive the prop. As the drive is tilted up, fewer and fewer nubs are in contact. Like one poster said, "gimmickey" but that is the fun of having an old boat, isn't it? What happens, is if operators apply power to the drive in the up position is wears the nubs off. There is no U-joint, this nub gear is the hinge point in the drive line.
When I pick up my boat on Friday, I'll be having a close look at these nub gears. I'm going to see if it is possible to manufacture them at my shop.
Ball Gears - and you should never run the outdrive in anything other than the fully down position. You can run tilted up a bit if you're coming in to beach at minimal speed - but that's it.
It's not trim - it's tilt.
The use of Ball Gears allows for the drive to be raised up a lot higher and to turn much further over than U-Joint outdrives.
As for the ball gears - for the late model drives you're speaking of you can find them on Ebay - they're not all that expensive.
People have built up existing ball gears by welding onto them - in place if you can believe it - and then dressing the balls with a Dremel. They say it works well and lasts a longtime. Can't prove it by me.
The parts are around, what model do you have?
There is a place in Wisconsin that I go to for parts, Rawhide.org. You have to buy the whole boat on the cheap, remove the lower unit and donate the boat back. The ball gears are easy to replace if that's the problem, if the vertical drive shaft or gear is broke it is replaceable also, just takes more time and effort. The cooling system where it connects to the lower unit is usually a sticking point also. Watch for water in the raise/lower unit also. Once working they're a good unit. Does it have electric shift or manual?