if check engine light is not illuminated i would think the carbon buildup was caused by the thermostat stuck open causing engine to run too cool,to remove i would use gas and a rag but not too much gas as to have gas pass by rings into crankcase, just dampen rag and rub and i would change oil before restart...
I think the haynes manual I have states to just carefully scrape it off, but that was with the pistons out of the motor. Don't think it would be a great idea to do it the motor.
As for the gas idea, I could be wrong but I don't think that gas will hardly touch that carbon buildup. I think you will need something stronger.
As for the gas idea, I could be wrong but I don't think that gas will hardly touch that carbon buildup. I think you will need something stronger.
i don't think gas would do much either but its the only thing i think that would be safe but i would to try to wipe it down to see if it might help a little but your best bet might be to put it back together and suck some seafoam into a vacuum line...i would not brush, scrape or take any chance getting any debris between piston and rings in this case it would be better to leave it alone and when you reach proper temp in the engine along with some seafoam it should clean itself...