Home › Forum › Ask A Member › 1971 9.8HP Mercury 110 lower unit seized › Re: 1971 9.8HP Mercury 110 lower unit seized
You will need the wrench to put the cover nut back in but you usually have to drill and split them out, regardless. Why waste your money on a wrench when you may give up on this motor?
Up until 1975, Mercurys had steel drive, prop and shift shafts. The shafts pit where the seals ride on them, the seals go bye bye, the water gets in and you have the situation that you have. In salt water areas, this is the rule, rather than the exception. However, it also happens to fresh water motors when people don’t pay attention to the lower unit. On the really bad ones, you can’t even keep impellers in them because the drive shaft is so rusted that exhaust leaks into the pump and the impeller runs dry and burns up.They ARE great runners; but this lower unit situation is the sad truth. You may even have gears that are so pitted that they can’t even be reused.
You may find that you can get it apart, free it up and it will physically function without a lot of parts. Heck, you could even fill the lower unit with PB Blaster and hope it will free up. However, it will never be right or reliable (It may even self-destruct quickly) until it is all taken apart and virtually everything in it is replaced. (You can repair the drive shaft with a speedi-sleeve, which is a lot cheaper than a new drive shaft but still stupid-expensive for what it is.) Mercurys 1976 and up have very high quality stainless shafts, so this is no longer an issue. FINALLY! From 1976 on, Mercury Marine has never looked back!
Long live American manufacturing!