Used 85 hp Mercury 850... What to look for?

Piece715

Senior Chief Petty Officer
Joined
Jan 26, 2009
Messages
757
I found a Mercury 850 on craigslist with power trim and tilt and controls for $700. According to the guy selling it it is an 80s-90s model and it still runs, firing up on the first crank. Now I haven't seen it yet but plan to soon. He didn't know if the carbs have ever been rebuilt or the compression. I am going to try to have him take me for a ride.. if that doesn't work definitely gonna hook it up to some muffs. These are the things i plan on looking at when i check it out:
*Turn the prop and watch the hub to make sure the prop shaft isnt bent as well as checking lower unit for signs of being grounded or rock damage
*make sure it hasnt been run in salt water
*Pull the bottom oil screw to make sure the oil isnt milky or have water in it
*Make sure that she is "peeing" properly to ensure not running hot as well as looking for flaking paint on the top that could indicate high temps
*Make sure it shifts easily into forward and reverse
*Check the serials on the motor to ensure they match, check bolts on head for any sign of previous work like rounded corners or mismatching bolts
*Put the tilt up and let it sit for a while to ensure no leaks

What else can I do to ensure I'm getting a good motor is this a good deal or steer clear? Any information would be greatly appreciated! I'm sure yall know tons more about this motor and what to look for! Thanks in advance!
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
28,080
Re: Used 85 hp Mercury 850... What to look for?

Compression and condition of gears, ign and other wiring condition are the important things. You will want to rebuild the waterpump, for piece of mind. Carbs will possibly be dirty as well. I assume you do all your own maintenance and repairs?

if he is correct on the year of the motor, it will have the 4 coil ADI ignition. Distributor ignition on that motor would place it in the early 70s.
 
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