Johnson 4 HP - How to tell if cylinder toast?

[outdoorsman37]

helllo. i was using my 4 hp the other day and it died and then i started it again and then it died for good. i couldn't even pull the cord. it doesn't move. there is a piece of metal and a metal attachment piece that was floating around under the cowl but i don't know if it is related. i pulled the plugs today and the bottom plug had caked on what looked like dirt but could be something else. i see the bottom piston head and it doesn't look like i can move it. i want to know an easy way i can diagnose it other than pulling the heads off. i am not sure if i pulled the head off i would even know if it was broken? i don't know if it has something to do with the pull cord apparatus. i can't turn the prop in one direction whether it is in gear or not. please tell me what steps i should take to diagnose this. Thanks! Rob

 

[steelespike]

Re: Johnson 4 HP - How to tell if cylinder toast?

Remove the recoil starter and try to turn the flywheel by hand.
If not then remove the leg and try again.Sometimes the drive shaft or gearcase seize.You could pull the head and look around.
Is the paint around the head
dark like its burnt?

 

[outdoorsman37]

Re: Johnson 4 HP - How to tell if cylinder toast?

well i took the whole thing apart. i had to cut a screw off the lower unit. was about to throw the whole thing out then i took a sledge hammer and hit the protruding piston and it moved slightly then i hit it again and then i could turn the flywheel easily and the whole thing seemed to work like it should. there is a ton of gunk in the cylinders though caked on carbon and gooey crap. what is the best way to clean it? i am going to clean and reassemble it now. thanks!

Rob