mercruiser 120 outboard oil

paul ages

Cadet
Joined
Jul 27, 2010
Messages
27
whoops... i put this in the mercury forum before, so i'm moving it here...

i'm new to this boat... well, all boats to tell you the truth, but i'm a car and motorcycle mechanic, so i'm not totally clueless.

that said, i just bought a 1968 fiberform continental hardtop, with a mercruiser 120 I/O. i took it out for a few outings, after having done a tuneup on the inboard and doing a water pump rebuild on the outdrive. it ran great for a bit, but developed outdrive problems this weekend.

what i didn't do was check the upper/lower oil. i know, stupid. the gears in the upper are fried... lesson learned. what i've read on here is that the upper and lower gears share oil and therefore if one is fried, so is the other. however, the manual reads:

"On models prior to approximately 1973, the two reservoirs are independent, and must be drained separately."

So my question is: is my lower fried too? I will be pulling it tomorrow and checking the lower oil, but it's pointless if they do in fact share oil and i should be looking for a replacement outdrive.

gearhousing.jpg
 
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