Cleaning pistons ... How to ??

[Jughead]

Piston Slap Happens when the Bore to Piston Clearance Gets Bigger.Usually not Noticable at RPMs Above an idle.

[GeeP]

Wow, old thread.   

As far as decarbonizing goes, a quick home-shop method is to use Scotch Brite pads available from NAPA along with mineral spirits or an emulsion degreaser.  These pads have an aluminum-friendly abrasive, and will not damage the parts when used by hand.  They also do a better job than a wire brush.  Scotch-brite, in conjunction with a few wooden scrapers serves well as a basic decarbonizing kit.

There are many soak decarbonizing solutions, both water-soluable and mineral base on the market.  They are generally used at elevated temperatures around 170 degrees.  If you decide to go this route, be sure that the solution is acceptable for use on aluminum.  Acidic solutions can cause hydrogen embrittlement.

Wire wheels and steel wool will eventually cause dissimilar metal corrosion of the aluminum pistons and should be avoided.  In addition to the possibility of setting up intergranular dissimilar metal corrosion, a powered wire wheel will cause cold flow and burnish the surface of an aluminum component.  This makes it impossible to check the components for cracks or other damage.

Under normal circumstances there is NO metal-to-metal contact in an internal combustion engine.  All surfaces are held apart by a very thin layer of oil.

[Jughead]

Oh yeah and what GeeP said too.