Driver rear coolant passage leaking due to gasket deterioration, I have it stripped down to the block and was surprised to find the valley pretty clean. (possibly due to an ATF flush) The bores still have the crosshatch pattern still in them, it never used oil either so im guessing the rings have seated ok. If any of you have done the headgaskets on the 4.0 did you notice the crosshatch pattern in your bores? No sunk sleeves either. My piston tops are carbonized and I had a question on cleaning them. What do I use to clean them? scotchbrite? a brass brush? any solvents? You know I had done an induction cleaning with seafoam 200 miles or so before the teardown and noticed the backs of the intake valves/guides really shiny clean, but the intake runners in the manifold and heads never really got that clean. But in seafoams defense I never saw the insides to begin with... I am sending the heads out tomorrow for the full teardown/valvejob/rebuild, I bought a timing chain/gears to install while im in there and some Kingsbourne wires as well (Thanks Spike) I took a bunch of pics from the start if anyone wants them all posted.

 

If it ain't broke, why fix it? Obviously your head gaskets needed to be replaced but it sounds like the cylinders are in god shape. If it were me I would leave the pistons alone. Cleaning them is going to be a temporary fix, if it does anything for you at all. Your pistons are always going to have a certain amount of carbon on them from the burning of the fuel in the cylinders.

If you insist on cleaning the piston tops, use something like a mild scotchbrite pad that isn't likely to scratch or gouge your pistons. Any imperfection you cause in the piston could open the door for serious problems.