Ring & piston scoring

[3dkid]

My 1998 90 horse Mercury Force, which I purchased new, has a scored piston and ring on the #2 cyl.(this is a 3 cyl. eng.) Serial #0E327238<br />Engine has had proper maintenance and no abuse, no overheating.<br />What causes piston and ring scoring?

 

[LubeDude]

Re: Ring & piston scoring

Im sure others can add to this list, but Ill give it a shot!!<br /><br />Overheating<br />Not enough oil, wrong oil<br />Lean condition<br />over revving<br /><br />Thats the normal ones!!<br /><br />with proper maintenance as you said, probably a lean condition due to:<br /><br />Pluged carb. Jet<br />air leak<br /><br />LubeDude

 

[walleyehed]

Re: Ring & piston scoring

LubeDude covered about all you need to know there.<br />One item mentioned may be the "cause" of the others.....Overheat causing break-down of oil.....bla, bla, bla.<br />As LD said, it would very possibly be a plugged jet, and that would be where I would start looking.........

 

[The Marine Doctor]

Re: Ring & piston scoring

#2 cyl.<br /><br />Prob not heat related as in Waterpump failure. I would guess the cyl ran lean or built up with carbon.<br /><br />TMD

 

[Kenny Bush]

Re: Ring & piston scoring

I think Carbon buildup is the biggest cause of piston scouring in motors that get babied there whole life. Here is comes......."SeaFoam" Put a can in gas tank every other fillup and drive your motor clean....yadayadyada... Anyway, I use it and have seen it work. You must remember that the cylinder is conical(Cone shaped) and the piston rings compress in(downstroke), and backout(upstroke) with every revolution..... When carbon builds up in the rings they begin to stick....piston begins to wobble...scoring is happening. Keep it clean with SeaFoam... I have seen it clean plugs up in about 20 hours of use... Bla bla.... BushCat clear back to 16.

 

[LubeDude]

Re: Ring & piston scoring

I may be missing something over the years, but how do you bore a cylynder in a "Cone shape"????? <br /><br />I have to admit, Thats a new one on me!!!<br /><br />LubeDude

 

[mellowyellow]

Re: Ring & piston scoring

no bushcat, it's a lean carb. <br />a "Carbon-free" motor without lube will die just<br />as quick.

 

[LubeDude]

Re: Ring & piston scoring

When this happened, did you notice a sudden change in RPMs like it started running at a higher RPM breifly before it died???<br /><br />Out of curiousity, what oil were you using??<br /><br />LubeDude

 

[mellowyellow]

Re: Ring & piston scoring

when a cylinder gets no lube it don't matter which<br />kind of oil yur using... say goodnight Gracie.