Removing Piston Top Carbon: How?
Burning Brakes
Joined: Aug 2013
Posts: 1,071
Likes: 322
From: palm springs ca
Adam,
I'm not going to say this is right, but in 1971 when I was working as a mechanic at Chevy we brought the piston to the top and used a scraper. Some motor bike guys did that followed by a wire wheel.
There was actually a carbon knock caused by carbon on the piston hitting the head. Many used water on a running engine poured in with the engine running about 2500, then GM came out with a carbon remover that was also poured down the carb to the point of stalling the engine with the last amount of liquid. Engines needed to be at operating temp for both methods. But where I am going with this is that some work orders were wrote to remove heads and carbon from pistons. Had to do what work order said. In your case blow it with air when done. Carbon comes off pistons with the engine running and doesn't hurt things and a few small pieces won't hurt a thing.
Dom
Dom
I'm not going to say this is right, but in 1971 when I was working as a mechanic at Chevy we brought the piston to the top and used a scraper. Some motor bike guys did that followed by a wire wheel.
There was actually a carbon knock caused by carbon on the piston hitting the head. Many used water on a running engine poured in with the engine running about 2500, then GM came out with a carbon remover that was also poured down the carb to the point of stalling the engine with the last amount of liquid. Engines needed to be at operating temp for both methods. But where I am going with this is that some work orders were wrote to remove heads and carbon from pistons. Had to do what work order said. In your case blow it with air when done. Carbon comes off pistons with the engine running and doesn't hurt things and a few small pieces won't hurt a thing.
Dom
Dom
Le Mans Master
Joined: Sep 2003
Posts: 8,812
Likes: 2,029
From: eastern NC
Adam, are the heads on or off?
If the heads are on, and the engine can run, misting water through the carburetor while the engine is running works to remove carbon.
If the heads are off, lacquer thinner can be used to remove light deposits. If the deposits are thicker, you can bring each piston to the top of its' bore and remove some of it with a razor blade being careful not to nick the piston top. Then use lacquer thinner to remove the rest. I would use the thinner on a rag, or a shop towel, not pour it on the piston directly to avoid getting it in the oil. Then again changing the oil is probably going to be necessary anyway if you have the heads off.
Good luck... GUSTO
If the heads are on, and the engine can run, misting water through the carburetor while the engine is running works to remove carbon.
If the heads are off, lacquer thinner can be used to remove light deposits. If the deposits are thicker, you can bring each piston to the top of its' bore and remove some of it with a razor blade being careful not to nick the piston top. Then use lacquer thinner to remove the rest. I would use the thinner on a rag, or a shop towel, not pour it on the piston directly to avoid getting it in the oil. Then again changing the oil is probably going to be necessary anyway if you have the heads off.
Good luck... GUSTO
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
x2 leave it be....if you HAVE to get the piston to the top, fill in the sides with vaseline or? so the gunk doesnt get down in the piston ring area.
Or just remove the big stuff and leave the rest be. Second you start it up youll start carboning things up again.
Always seems like a good idea til you see how messy it is then wish you hadnt lol.
Or just remove the big stuff and leave the rest be. Second you start it up youll start carboning things up again.
Always seems like a good idea til you see how messy it is then wish you hadnt lol.
Drifting
Joined: Jul 2015
Posts: 1,765
Likes: 254
From: Catlett VA
I'm old enough to remember when removing the heads to scrape of carbon buildup was a routine maintenance job in old cars from the 1950s and older- usually every 10-15K miles. This was before modern gasoline formulations eliminated almost all heavy carbon buildup. Unless there is a real problem that can be directly attributed to heavy carbon buildup and not to ignition timing, poor air-fuel mixture, bad spark plugs, etc., this is something that you do not need to do. If you actually do have heavy buildup it is often from oil getting in the combustion chamber- worn out piston rings, bad valve oil seals.
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Burning Brakes
Joined: Aug 2013
Posts: 1,071
Likes: 322
From: palm springs ca
I'm old enough to remember when removing the heads to scrape of carbon buildup was a routine maintenance job in old cars from the 1950s and older- usually every 10-15K miles. This was before modern gasoline formulations eliminated almost all heavy carbon buildup. Unless there is a real problem that can be directly attributed to heavy carbon buildup and not to ignition timing, poor air-fuel mixture, bad spark plugs, etc., this is something that you do not need to do. If you actually do have heavy buildup it is often from oil getting in the combustion chamber- worn out piston rings, bad valve oil seals.
I also remember especially in my prior post. The Brits called it de carbonizing kits. What amazed me was water injection units that were sold when fuel octane got bad. The pistons were carbon free on top and you could read the #'s. The water expanded into steam which increased combustion and steamed the carbon off the pistons. Edelbrock sold the ones I used. I could tell when the water tank was empty because the engine would start pinging.
Dom
Racer
Joined: Feb 2002
Posts: 378
Likes: 19
Bring each piston up to TDC, and use a razor blade in one hand and a vacuum in the other to catch the carbon bits, especially at the edges of the pistons so that carbon does not get lodged between the top ring and the cylinder. Then go over that now mostly clean piston with lacquer thinner. and paper towel. If the carbon is really bad, suppose you'll need to use an electric drill with a wire wheel. Don't forget to have the vacuum nozzle in the other hand. Resist the temptation to wire wheel the block deck or head gasket surface. Use the razor, scotbrite and lacquer thinner there as well.
Burning Brakes
Joined: Aug 2013
Posts: 1,071
Likes: 322
From: palm springs ca
Bring each piston up to TDC, and use a razor blade in one hand and a vacuum in the other to catch the carbon bits, especially at the edges of the pistons so that carbon does not get lodged between the top ring and the cylinder. Then go over that now mostly clean piston with lacquer thinner. and paper towel. If the carbon is really bad, suppose you'll need to use an electric drill with a wire wheel. Don't forget to have the vacuum nozzle in the other hand. Resist the temptation to wire wheel the block deck or head gasket surface. Use the razor, scotbrite and lacquer thinner there as well.
Dom
Had a 1976 L-82, 4-sp
Joined: Mar 2011
Posts: 5,338
Likes: 1,213
From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
I used a spray can of Permatex gasket remover. Let it sit a few minutes and wipe off. Doesn't get much easier than that. KISS!!!
Le Mans Master
Joined: Mar 2001
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From: Lincoln, CA
Thread Starter
Melting Slicks
Joined: Jun 2016
Posts: 2,979
Likes: 332
From: Woodinville WA
I've seen gasket remover come up again and again as a good solution.
Here's my plan:
Thanks all!
Adam
Here's my plan:
- spray gasket remover and let sit 10 min
- Scrub with scotchbrite pads
- remove crud with blue shop towels
- Repeat above
- Use brass dremel brush for any crusties left
- Move piston down and wipe any crud that comes out
Thanks all!
Adam
Last edited by NewbVetteGuy; Sep 14, 2018 at 05:39 PM.
Safety Car
Joined: Jun 2017
Posts: 4,786
Likes: 425
From: North Georgia, USA
I've used "3M Roloc Bristle Discs" to remove carbon from piston crowns. They are a bit pricey ($7 to $10 each depending on the quantity you get). The white ones are the "finest" ones they have. They are rated at "120 grit" but there's not much abrasive on the tip of each little bristle. It works mostly like a brush you can put in a die grinder or on a variable speed drill.
Cleaning carbon from piston crowns is best done when the pistons are out of the bores, so the crud you clean off the top of the piston doesn't migrate into the rings and cause even more problems.
Cleaning carbon from piston crowns is best done when the pistons are out of the bores, so the crud you clean off the top of the piston doesn't migrate into the rings and cause even more problems.
Thread Starter
Melting Slicks
Joined: Jun 2016
Posts: 2,979
Likes: 332
From: Woodinville WA
Update: I just used CRC gasket remover today and it’s like magic; just spray it on, leave it for 2-3 hours, and wipe off with paper towels.
It just liquifies the carbon! They should call it carbon remover.
Theres no way any other method can beat this one.
Adam
It just liquifies the carbon! They should call it carbon remover.
Theres no way any other method can beat this one.
Adam
Thread Starter
Melting Slicks
Joined: Jun 2016
Posts: 2,979
Likes: 332
From: Woodinville WA
Instructor
Joined: Mar 2010
Posts: 162
Likes: 8
Not predominantly this thread, but maybe others like, "one headlight is not working".
A Corvette, is just a car, right?
Last edited by Steve Ference; Oct 14, 2018 at 04:46 PM.