The Stovebolt Site Forums The Shop Area Engine Shop Removing carbon from pistons

This may have been discussed here, but I thought I would share anyhow. Was cleaning a block and using oven cleaner to strip the grease, oil and paint. Experimented on a piston with carbon deposits. Let it sit for a few hours. The carbon build up wiped off with a paper towel. No scraping or scratching the piston top, surprised how easy it wiped off.

Going to give this a try on some exhaust valves and see what happens.

Oven cleaner or caustic soda can corrode aluminum. lemon juice will neutralize it...then wash with soap and water afterward.

Carbon is a weak acid.

Oven cleaner usually has a pH greater then 12. The pH scale ranges from 1 to 14, with 1 being extremely acidic, 7 being neutral, and 14 being extremely alkaline

How about the carbon buildup in the bottom of the piston ring grooves? I've got a couple of dedicated tools for cleaning the grooves out, but a lot of people don't even realize that needs to be done! I've seen pistons get stuck partway down a tapered cylinder when the new rings bottom out on the carbon layer.
Jerry

Yeah those grooves can be problematic and difficult to clean out. Was studying that the other day and trying to clean them.

If you don't have the groove cleaning tool, use a dull hacksaw or Sawzall blade and scrape the carbon out by hand- - - - -carefully.
Search Ebay for "piston groove cleaner"- - - - - - -there's a bunch of them available, dirt cheap!
Jerry

Before I was married, I ran engine components through the dishwasher. That worked very well but I don't think I could get away with it anymore.

My "special tool" for cleaning out ring grooves was one of the rings off the pistons, broken in about a quarter of the diameter and the end used to scrape the carbon out. Cheaper than "dirt cheap", and works pretty well.

Kevin
That's how my dad taught me!

Don

Ditto. Wrap some tape around the end you’re holding to make it easier on your fingers.🛠

Thin layer (no flakes) of carbon on the piston crown: harmless.

Questions about carbon build up...

Once carbon starts to form on the piston does that aid or enable it build up faster, giving it more of a foundation to grab on to and accelerating carbon build? In my mindless wanderings while I work on mindless tasks - I was thinking that a clean piston would slow the opportunity for additional carbon build?

Last, do carbon deposits enable engine ping and lower fuel burn?

Just some questions to help me better understand, while I go back to another mindless task.

Tom

Depending on several factors like the bore size and the combustion chamber volume, a layer of carbon on a piston crown can raise the compression ratio a little. Rough or uneven buildup increases turbulence as the flame front travels across the combustion chamber, and if a glowing hot spot develops opposite the spark plug a second flame front can form, causing detonation when the two opposing flames meet in the middle.
Jerry

Most of the new pistons are polished on top, one to reflect the heat back, and two, so nothing sticks to them. Carbon will build faster once it takes hold, but if you keep the engine in tune, then you won't have a problem. If the pistons are out, I would polish them up with out altering the shape or size. On the plus side, they look cool being polished!