Mercury Outboard Lower Unit Noises.....

[Fr. Frank]

I had a similar noise from the lower on my 92 Merc 150. It would click while idling in fwd, but not in reverse. After not figuring it out, and then leaving it alone, I learned it was caused by the bearing carrier shifting backwards on the threads in the gearcase, which was cause by galvanic corrosion of the threaded portion of the gear case. I ended up rebuilding with a NOS gearcase with new clutch dog, pinion gear, reverse gear, and bearing & bearing carrier. Cost: $930.