I just pulled the head off of my Accord and the tops of the pistons are covered with carbon (what do you expect after 250K miles??!!) What's the best way to clean the carbon off the pistons while they're still in the block?
Thanks.

 

Spray them down with carb cleaner/throttle body cleaner. Let them soak for a while, keep spraying if neccessary. Then rotate the crank shaft until the number one piston is at TDC. It will be out of the cylinder hole .002" and that will allow you to use s nylon brush to scrub them clean. Rotate the crank for each piston and do the same.

*Note, drain the oil and leave the drain bolt out of the block to allow any cleaner that gets past the rings to drip out. Allow the block time for the cleaner to evaporate before adding oil. How long all depends on how much cleaner you spray in the block.

 

Thanks, GA. I'll give it a try.

 

Good info, I'mma be pulling my head in a few weeks here, so I might need to do this if they're carbed up.

 

Note*, You should also ensure that you wipe each cylinder wall down with a generous coating of oil when you are finished cleaning the piston. You don't want to leave the cylinders washed & dry. To do this you rotate the crank to BDC (piston is all the way to the bottom) and then take a clean lint free cloth, add a generous amount of clean engine oil, and wipe the cylinder wall down. Make sure that you coat the entire cylinder surface.

 

Leave it there. More compression.

 

Marvel Mystery Oil seems to be better suited for this. TB cleaner will just evaporate.