No responses, yet, bumping...I've read carefully everything I can find, there was an especially informative post chock full of suggestions with another stuck merc lower unit from last year, lots of references to turning the motor over and soaking the driveshaft with penetrant, using a slide hammer, etc. but before I get radical on mine I want to make absolutely certain that I'm not being deceived by my manual. I've removed the bolt under the trim tab, and the nut just forward of the trim tab, and have loosened the 2 nuts just above the anti cav plate along the sides toward the front, and the lower unit drops down no more than about 1/8th of an inch (sound familiar?) and then stops. I've rubber malleted it, I've teased, tugged, smacked, wiggled, jiggled, begged, cussed, pled and prayed, but it won't drop any further. What has me really concerned is that I can just barely see what looks like a threaded bolt or rod at the very front of the lower unit when I peek through the gap there, and my manual (seloc publications 2 stroke, 2 cylinder, (1965 to 1989 I think)) makes no mention of any bolt there needing removal, and the exploded diagram neither shows clearly nor explains what this might be. This is a type B lower unit according to my manual. Is there another bolt hidden under the intermediate/exhaust housing at the very front of this lower unit? serial number is 5660873 to confirm year.Expecting that there may not be another there and that I may just have a rust problem, what specific techniques have worked for the experts in getting a stuck lower unit removed? in the post I referenced above, the fellow posted a success, but didn't say exactly what had done the trick among the many suggestions that he had tried...This motor has seen a LOT of salt water use, so it could just be rusted to the crank, or maybe wedged with some dried out grease as the above mentioned poster's was. Your help will be much appreciated, as I really don't want to beat this thing into pieces only to find that I had missed a bolt, or neglected to employ some enlightened approach for lack of knowledge... Thanks!
I recently found the problem with my lower unit, 2001 90 Merc and thought I would pass along the information.My unit was stuch hard. I beat, pried, jumped on etc... to no evail. Finally with the help of a seasoned mechanic, we determined the drive shaft was seized in the power head. We had to drill a small hole in the rear of the casing and use an impact hammer to jar the thing loose. It's a small hole that I filled with JB weld and is covered by the lower half of the cowling cover.Follow the advise given here. drop the thing once a year and make sure to grease the shaft. Good luck. JB