Free motor, is it any good

[Retired]

I have to apportunity to get a 1981 115HP Johnson for free, with a 17' Glastron and trailer. MY question is: the boat has been out of the water for 5 years, with out being propely pickled, I think. With the plugs removed I sprayed WD 40 and 2 cycle oil inot each cylinder, when I manually turn over the motor there is a slight "scraping" sound, is this something that will wear off or does it sound like the pistons and cylinders should be taken apart and examined? Overall, the condition of the motor looks pretty good. Joe.

 

[DJ]

Re: Free motor, is it any good

I would not start it until I found the source of the noise. It could be something scraping under the flywheel too.<br /><br />I would get a borescope or pull the cylinder heads if the source of the scraping is in a cylinder. <br /><br />Sounds like a fun project.

 

[Walker]

Re: Free motor, is it any good

Could be the impellor you are hearing. Needs replacing anyway after 5 years of sitting. <br />WD40 is sorry fogging oil too.<br />I'd get the starter working and with the plugs out I'd fog the heck out of it thru the carbs with the starter cranking.

 

[randycc58]

Re: Free motor, is it any good

I got an old 70 hp johnson given to me once. It was tight to turn by hand without the plugs in it.<br /> An old trick I learned from a shade tree mechanic helped me. I'll pass it on to you.<br /> Tilt the motor up and remove the plugs. Now don't go crazy here. Pour a small amount of marvel mystery oil in each spark plug port and let it sit over night. The next day slightly move it back and forth. add a little more and let it sit again. If it spins freely, you may be ready to spin it with the starter. If you suspect rusted up bores, a bore scope can be used to look further. Or remove the heads. Do not attempt to reuse the head gaskets. Dont try to spin the motor @ high rpm without first getting some lube in there. Mystery oil will not dry out like WD40.Oh and before I forget. When you do attempt to spin it with the starter... Don't stand in front of the spark plug holes, as you will smell like mystery oil. If you already tried to spin it without the lude you may have already scored the bores.

 

[DJ]

Re: Free motor, is it any good

Good point about the impeller!!<br /><br />Forgot that one-brain cramp.

 

[1986mariner150]

Re: Free motor, is it any good

those are some tough old motors, imnsho they are as close to bullet proof as you can get. Do a compression test before you spin it too much and look for equal compression. If you find one low shoot some 2 cycle oin in the spark plug hole and spin it over by hand a few times to hopefully break it loss. This may take a couple of days to penetrate. If it starts with a stuck ring it will scar the cylinder wall with a quickness. If you have good compression move on to the carbs, they will need disassembly and cleaning. I usually get it cranked up before taking the carbs apart. I do a on the boat cleaning with spray carb cleaner first, it is not real popular around here, but I have yet to take out a piston, I currently have 4 outboards that have sit and all run great with excellent compression. I don't like throwing parts into an engine that I know nothing about, so I try and get it to start before i buy anything except gas, oil, carb cleaner, and deep creep. So far I am batting a thousand. Be sure and use a clean tank with fresh gas and oil in it.