Johnson GT 150 Rusted piston to bore

[PeterUK]

Hi everybody,<br />I posted last month about my problem with a siezed motor.<br />I have found why the motor was siezed, the person who last drove the boat sucked water into the motor and left it like this for a year,,,,,is it possible to loosten the pistons off with some kind of penetrating oil and if so is there any other way of doing this. I have left the boat twice now for two weeks bothe times emptying a whole can of penetrating oil into tyhe motor.Any sugestions would be appreciated........exept a hammer and chizel

 

[OBJ]

Re: Johnson GT 150 Rusted piston to bore

Pete....if it's rusted that bad, don't even bother about getting it lose. Chances are it may be more than just the piston froze up. Tear it down....if it's worth the trouble.<br /><br />But if your determined to get it lose, find a wood dowel that you can put through the spark plug hole. Put it against the piston and smack it with a hammer.....try not to drive the dowel through the top of the piston.... If this don't work.....pull it apart.

 

[DHPMARINE]

Re: Johnson GT 150 Rusted piston to bore

PeterUK,<br /><br />One of the good/bad things here is everyone has their 2cents worth,so here's mine.<br /><br />Had the same thing years ago.Worked at it with oils,tapping,everything I could think of.Finally got it to turn 360% by the flywheel nut.Kept at it until it would crank like normal with the starter motor.Fired her up,sqirting 50:1 in the carbs while she ran for 20 minutes.Restarted the next day,it ran about 3 minutes,developed a knock and seized.<br /><br />So ... if the motor is old,and not worth it,try what I did.I'd do it again.But if the motor is newer,or your labor is cheaper,tear it down,do it right.<br /><br />DHP

 

[DHPMARINE]

Re: Johnson GT 150 Rusted piston to bore

forgot to add,I think the real problem was the lower crank/connecting rod bearing,and the piston wasn't the real culprit.<br /><br />DHP

 

[rodbolt]

Re: Johnson GT 150 Rusted piston to bore

it may be rebuidable now. if you start hammering on it you may have a total junker. even if you do get it to break free it wont last very long and will destroy itself. if you hope to salvage any of it carefully dissaseble it and see if the crank and rods are damaged. roller bearings dont like shock loads. then ya have to find the entry point of the water and why.