Re: Johnson J75TLCNB 1982 75 hp

[Don]

Well, I am assuming this is a fresh water engine…If not, its value is less due to corroded fasteners etc.
The 75hp version of the 3 cylinder OMC is a bit more prone to detonation/preignition damage than its 70hp counterpart…So, bring your compression tester. Other than that, look for idle/sync adjustments that are way out of whack, this is usually an indication that someone has attempted to make a worn out powerhead idle acceptably. Idle quality is a pretty good indicator of powerhead condition on these engines, but only if run on a boat in the water…Running the engine on a flushette won’t tell much in its no load/back pressure condition. Look for signs of overheating also, try to determine why the seller is getting rid of what is usually a pretty decent engine. I would be interested in knowing what type/length boat the engine was used on and what size pitch prop was being used. Over propping these engines on larger non performance hulls is a pretty good way to damage the powerhead.
Other than looking for obvious physical damages to castings/gearcase, look to see if the engine still has its original powerhead, look for signs of being rebuilt also. The power trim units on these engines are pretty rugged, but look for obvious leaks like Bob suggested. You will need the power trim harness/junction box along with a control box for this engine, so be sure to get that from the seller.
Good luck, hope you get a good one for a reasonable price, how much does the seller want for the engine?