[footjoy]

I pulled the motor to do some work, and the pistons have excessive amount of carbon on the piston tops.

What is the best way to get the carbon off?

Thanks
Greg

[Scott65]

Pistons out of the block or in?

[footjoy]

Originally Posted by Scott65

Pistons out of the block or in?

They are in the block

[64speed]

Sea foam one bottle in the tank and one bottle SLOWLY sucked up by a vacuum hose and left to sit 15 minutes then fired up

[footjoy]

The engine is out of the car with the heads off. I should have been more clear.

Greg

[Scott65]

I've used a plastic scraper, hovering with a shop vac running to get the heavy stuff. Locate and avoid the top ring gap area to keep trash from getting inside. Once you get the heavy stuff, carb cleaner with lint free rags will help with what's left. Maybe some scotchbrite, again avoiding the opening in the ring gap. Worked for me. I'm sure you'll get some other suggestions.

[64speed]

Sorry I didn’t catch the part about the engine being out of the car. I’d still use sea foam with a toothbrush dipped in it. Should clean right up

[maxpowerta]

seafoam does absolutely nothing to clean carbon off of cold pistons, ive left pistons soaking in it for days and they came out looking the same as when they were put in. Carb cleaner works or if you can soak them the best stuff ive found for melting carbon right off is "spray nine"

[crm318]

Gel type aircraft paint remover.

[steve25]

The first thing to do is oil up the edge of the top of the piston and the area of the top ring land with some spray WD-40.
Next get some clay and fill that oiled area in so that you can then scrape the Carbon off with single edge blade and then vacuum the top of the piston off and get no crap down into the ring land.
Of course remove the clay after the vacuum session.

Also news paper and tape off the lifter valley as this type of Carbon crap can keep the oil pump check ball unseated, and you don't need that issue.

[77 TRASHCAN]

Transmission fluid will do the job...

[455rebel]

Bring piston to top, then wire brush on a drill?
Brake fluid softens it also.

[Grand73Am]

I tried a few other things first, but no solvents were effective. So, I used abrasive discs, like Scotch-brite Roloc discs with an angle air drill. It was the fastest and most efficient way I found. Below are pics of when I cleaned the carbon off my 403 Olds, before and after. I rotated the piston I was working on to the top, covered the rest of the engine, and cleaned that piston. Then do the same for the next. Using clay is a good idea to seal off around the edge of the piston to keep abrasive material from getting between the piston and the cylinder wall. I used a vacuum to remove debris from the piston top and around the perimeter gap. Wipe with some brake cleaner and then squirt oil in the piston gap before rotating the crank to the bring the next piston up.

Some may say using the Scotch-brite disc is risky due to the fine abrasives embedded in the scotch-brite material. But, if you take the precautions to keep it out of the gap between the piston and cylinder, and off the rest of the engine, it shouldn't be a problem. This was a used engine I bought that I just wanted to clean up, replace cam, gears, and chain, re-seal and use it. After oil priming the engine, and cam break-in, I changed the break-in oil and filter, and I've had no problems over the last 2 years I've been driving this engine. Runs great.

DSCN3526 by grand73am, on Flickr

DSCN5102 by grand73am, on Flickr

[KEN CROCIE]

Bite the bullet and pull the pistons. Mask off the rings and hit them with the wire brush side of your bench grinder. No worries about getting debris in the ring gaps or cylinder walls or valley

[taff2]

Turn the engine upside down in the engine stand and lie under it to scrape the carbon off, it will fall to the floor instead of down into the rings/bore.

[shaker455]

However you decide to clean installed in the block just keep any debri away from the edges that can get stuffed into the top ring.
Vacuum it out and if you use any scotch-brite make sure it all out as that will wreck your day.

[Formulas]

I use this xacto tool with a chisel blade, the blade is a half inch wide,

Great gasket scraper in general

.

[HWYSTR455]

CRC gasket remover works great, even says on the can that it can be used to remove carbon build up, but not sure they make it anymore.

Guess they do:

https://www.fcpeuro.com/products/crc...iABEgK-gfD_BwE

But looks like you took care of it anyway.

The gel aircraft paint remover works too, but it will eat cast pistons.


.

[coonhunter70]

Wet it with diesel fuel and trans fluid let sit overnight is what I would start with.

[P@blo]

Originally Posted by 64speed

Sea foam one bottle in the tank and one bottle SLOWLY sucked up by a vacuum hose and left to sit 15 minutes then fired up

Wasnt seafoam proven a scam for 4 stroke engines?