Thoughts on letting it push the G3 across the water?
Ever since I picked up my G3, I've been wanting a I-6 Merc...but nothing decent ever seems to pop up anywhere near me.
Don't know much about these older Evinrudes. Guy says it got very little use and hasn't been on a boat in well over 10 years. I do know about the possible water pump impeller issues and have heard you can tell alot by the condition of the paint on the heads and block...paint looks perfect.
135hp will push a G3 scary fast, even dangerous fast. Kill switch, dual steering, life vest, etc for safety. Others will chime in with other safety and setup advice, but please put safety first. Not all of my gray hairs are from my kids, but I'll never admit it. Oops, guess I just did.
135's have lots of compression and need a real strong battery & excellent wiring/connections to spin the starter over properly.
Also very susceptible to poor-quality fuel, if you can get fuel without ethanol, by all means use it. Better yet, if you can latch on to some 100 Octane Low Lead (100 L/L) Avgas, it'll really like that.
If I recall correctly, OMC came out with low-compression head gaskets, so you might ask the owner if he knows if they were installed. They are thicker than stock and lower the compression to Less-than-Insane levels. The motor makes a few less Ponies, but is a lot easier to live with.
If you are forced to run ethanol-blended fuels, be sure to use a dose of Stabil Marine or Startron fuel stabilizers in every tank; these motors are so sensitive to fuel quality that the residual fuel in the fuel lines & carbs, if degraded from sitting too long, can cause engine damage from detonation.
At least with stabilizer added, you have a chance of keeping the fuel fresher for longer.
But as was said earlier, it'll be Scary Fast on a G3 hull, so hang on tight and maybe wear a helmet!
Do change the impeller if it hasn't been done in the last few years, definitely a must to keep the cooling system up-to-snuff on this motor.
Before paying good money for this or any motor, run it on a stand, or on a boat even better. On a stand, you can slide a 55-gal or 35-gal plastic garbage can over the motor and fill it up about halfway up the exhaust leg.
The motor should start and idle well, it should sound crisp, not sluggish when the throttle is "blipped". It shouldn't make any unusual knocking or "thrashy" bearing noises.
Check to see if the block warms up properly (i.e., thermostats working), while the exhaust plate (probably an exhaust "bubble") stays noticeably cooler than the block.
I can't recall if the old 135's have a telltale, but with the motor in a "bucket" you should get some water out the exhaust reliefs when the thermostats start to open and the throttle is blipped. Be careful not to rev to an extreme amount, these V4's have big pistons & long stroke, and aren't happy to rev like a Merc, you can put a rod thru the side of the block!
After running, pull the lower drain plug on the gearcase and check for condition of oil. Any milky-looking stuff means a bad seal, likely on the driveshaft. Definitely a bargaining point.
If you can't run the motor, then assume it's good for parts. Never pay top dollar for a motor you can't hear running!
If you can't hear it run, a large discount is in order, or just walk away. There'll be a Merc out there somewhere for ya!
Too bad you're not close to the Good Dr. Frankenmerc here in the PNW, he's got plenty!
Anyway, if she sounds sharp and looks sharp, you may have yourself a winner!