Fordiesel69 233 #1 Posted May 15, 2014 In the process of decarboning an oil burning, 1700 hr Kohler M12, and someone let it go too long. It has never been cracked open. The carbon was thick and did not seem to come off easily. After an hour of cleaning, I am still wondering how bad it is down in the ring packs. I am one for ripping the engine apart, manually cleaning the ring grooves, and inspecting & replacing the rings if needed, however for this person it is not an option due to budget. I have all kinds of chemicals that would work great for a piston soak, however I question its effectivness down in the ring area. It burns oil on acceleration or under a heavy load, but not just running at speed. I want to reduce the oil burning as much as possible to limit the chance of this person running it low on oil. Share this post Link to post Share on other sites
oldredrider 2,548 #2 Posted May 15, 2014 Soaking a piston is not really worth it, in my opinion. You are aware of the proper way to go at the mechanical side of the motor. Doing is halfway just temporarily prolongs a certain early death. It's a tough call when budget constraints come into play, but doing it properly saves more money in the long run. 1 Share this post Link to post Share on other sites
gwest_ca-(File Mod) 10,539 #3 Posted May 15, 2014 I would run it on a healthy diet of Marvel Mystery oil in the fuel. There is something in it that does not burn off and if the rings are stuck it should free them. Garry 1 Share this post Link to post Share on other sites
Fordiesel69 233 #4 Posted May 15, 2014 Would soaking 100% MMO in the cylinder be a better alternative as I do not beleive this person will know how, or care to mix it in with the fuel. Share this post Link to post Share on other sites
gwest_ca-(File Mod) 10,539 #5 Posted May 15, 2014 It may. Run the piston down a bit and every once in a while jerk the flywheel back and forth to work the rings. Garry Share this post Link to post Share on other sites
buckrancher 2,678 #6 Posted May 15, 2014 you can remove the piston and rings to clean them just hone the cylinder before you reassemble it Brian 1 Share this post Link to post Share on other sites
shorts 182 #7 Posted May 16, 2014 If your not prepared to at the minimum deglaze the cylinder and replace the rings leave the piston in the cylinder and don't worry about the carbon buildup behind the rings, if their wasn't room for it, it wouldn't have built up in the first place. Share this post Link to post Share on other sites
Fordiesel69 233 #8 Posted May 16, 2014 Bad news....... the homebrew solvents I mixed to do the piston soak, leaked thru to the crankcase overnight. Good thing I did not change the oil before..... The curiosity of a teardown is killing me, and at this point I would almost want to do the labor for free just to see how bad. However we all know what happens when you open up a can of worms...... If it was just carbon, the solvent would not have just leaked thru overnight. Still burns the same amount of oil, but with the reduction of carbon, there is no more engine knock. Share this post Link to post Share on other sites
shorts 182 #9 Posted May 18, 2014 If your piston soak solvent is thin enough to get past the top of the piston to the rings it should be able to get thru the ring gaps and past the piston skirt to the crankcase. you will have some taper in the cylinder caused by the increased pressure when the piston is at top dead center, it will also probably have ring to groove clearance issues due to wear Share this post Link to post Share on other sites
Fordiesel69 233 #10 Posted May 18, 2014 Yep it was thin enough to leak down, however the rings are just bad. Again, like I thought, you can't fix a mechanical problem with magic. Now a piston soak might be good on a perfectly running engine to KEEP the rings good, but I think in this case it is too late. Share this post Link to post Share on other sites
shorts 182 #11 Posted May 19, 2014 snake oil, smoke and mirrors or you can just save your money and fix it the right way the first time Share this post Link to post Share on other sites
