Carbon scrapers

What are people using to scrape the carbon from the top of pistons and inside the cylinder head? I've been trying brass, copper aluminium old bread knife etc, all either too hard or too soft. Is there anything that will soften the carbon to make removal easier?

WFO seems to work well.... :wink: :mrgreen:






But seriously, a wood chisel, used like a surgeon will work. Or SHARP gasket scraper (same shape)

Unfortunately, carbon is harder than aluminum, so what ever will work must be used with great care. There's probably no product out there than can soften carbon that won't damage the piston top either.

Well, I'm currently working on turbocharged rotax 914 aircraft engines and what we do on a partial rebuild at 720 hours is pull the heads off and use a media blaster to clean them up. But since we leave the cylinders on the block, we spray wd-40 on the piston crowns (since they are still in their bores) then we use a 3m drill attachment that is plastic or nylon /synthetic and is yellow and has little fingers all around the face of it. You gotta use a fair amount of pressure as you scrub the top of the piston, but it doesn't scratch or marr the aluminum. Additionally, we sometimes supplement that process with green scrubby pads / kind of like the ones on the back of some kitchen sponges, but corser.