1992 merc 200 efi scored piston

[boats11]

i just got some bad news today on my motor.i have a 92 merc 200 efi with the number 1 piston scored.my 5 other cylinders are fine with 138 psi compression in them.i have always babied this motor with utmost care.my mechanic is telling me to rebore the block to .015 over factory specs and to have oversize pistons placed in.is this the common practice for this problem?any info on how this happened would be greatly appreciated.thanks soo much

 

[LubeDude]

Re: 1992 merc 200 efi scored piston

The very first thing you need to find out is why it happened in the first place, Then, depending on how bad it is you might be able to just hone and replace the piston. If thats not posable, I would just have on cylinder bored and hone and rering the rest. Just my opinion.

 

[boats11]

Re: 1992 merc 200 efi scored piston

thanks for the reply lube, we are in the process of finding out what happened.possibly 3 things? not enough fuel for lubrication,oil pump but every other cylinder was fine,or just got too hot but i know that i was pumping water and my gauges were reading fine at 172 degrees.thanks again for your quick response

 

[2springers26]

Re: 1992 merc 200 efi scored piston

WHAT CYL FAILED.. WHERE ON THE PISTON DID IT FAIL.. EX PORT?? DETINATION??? WE NEED SOME MORE INFO... AS FOR REPAIR.. YOU NEED TO MIC THE CYLS FOR OUT OF ROUND.. THAT WILL DECIDE ON WHAT YOUR GOING TO DO AS TO ALL SIX PISTONS OR REPAIR JUST THE ONE CYL... BEING A 92 i'D SAY ALL 6 UNLEES THE MOTOR HAS LOW HOURS... SINCE YOUR IN THE MOTOR NEW CRANK & ROD BEARINGS ARE A MUST...