Piston Head Cleaning

[Hector]

What is the best way to clean the top of the pistons other than scrapping off carbon deposits?

[632 Regal]

try to keep it from draining down the side of the cylinders/pistons, maybe use tape.

[Hector]

Thanks. Thinner might be tricky or perhaps impossible to contain on the piston head. Yeah, I don't want this stuff running down through the cylinder wall. I'll probably wind up doing what I did with my Mazda, moisten a rag with solvent and carefully wet the cylinder head and let set for a while until the deposits become soft and easily "scrapeable." However, this takes a long time and was wondering if there was a quicker way. I know some people here have been faced with this before and was hoping to learn the tricks of this trade.

[bimmernut]

use Marvel mystery oil. let it soak over night, then clean off the next day. also help keep engine clean. add a qt. to crank case 500 miles before oil change. can also add to gas as directed on can. good stuff.

[Hector]

Used to add a couple of scoops (about 3 tbls) of this stuff after each oil change in previously own vehicles. Seem to work. Thanks for the suggestion.


use Marvel mystery oil. let it soak over night, then clean off the next day. also help keep engine clean. add a qt. to crank case 500 miles before oil change. can also add to gas as directed on can. good stuff.

[Hector]

Gee-whiz. Is this topic a real stumper? Any others who care to take this subject on? Going once,...

[Bill R.]

best way is without scraping the carbon... the procedure I have used for the last 30 years is to rotate each cylinder to the top and scrape the carbon carefully with a scraper, then i use compressed air to blow out as much of the dry flakes from the cylinders and around the ring lands, Next i use a scotchbrite pad with some carb spray cleaner or brake spray cleaner to finish off the top... then wipe it out as much as possible.. when its wiped out I rotat e the crank to bring it to the bottom and then wipe the cylinder out of any little bits or carb cleaner that i didn't get , i repeat the rotation a couple of times then I wipe down the cylinder with oil when its at the bottom to provide some lube upon startup.. I save the wipe down with oil until last after all the pistons, top of the block, threaded holes have been scraped, tapped cleaned and dried. But like I said my method involves scraping.






Gee-whiz. Is this topic a real stumper? Any others who care to take this subject on? Going once,...

[632 Regal]

best way is without scraping the carbon... the procedure I have used for the last 30 years is to rotate each cylinder to the top and scrape the carbon carefully with a scraper, then i use compressed air to blow out as much of the dry flakes from the cylinders and around the ring lands, Next i use a scotchbrite pad with some carb spray cleaner or brake spray cleaner to finish off the top... then wipe it out as much as possible.. when its wiped out I rotat e the crank to bring it to the bottom and then wipe the cylinder out of any little bits or carb cleaner that i didn't get , i repeat the rotation a couple of times then I wipe down the cylinder with oil when its at the bottom to provide some lube upon startup.. I save the wipe down with oil until last after all the pistons, top of the block, threaded holes have been scraped, tapped cleaned and dried. But like I said my method involves scraping.

[Hector]

that the pros used a different technique for carbon deposit removal. Thanks for bringing your method to the table.

I guess the good thing is that if I have too much chemical inadvertently running down the cylinder, and since the oil pan will have been removed, then I could clean off residual solvent more effectively from underneath the engine. We will see.


best way is without scraping the carbon... the procedure I have used for the last 30 years is to rotate each cylinder to the top and scrape the carbon carefully with a scraper, then i use compressed air to blow out as much of the dry flakes from the cylinders and around the ring lands, Next i use a scotchbrite pad with some carb spray cleaner or brake spray cleaner to finish off the top... then wipe it out as much as possible.. when its wiped out I rotat e the crank to bring it to the bottom and then wipe the cylinder out of any little bits or carb cleaner that i didn't get , i repeat the rotation a couple of times then I wipe down the cylinder with oil when its at the bottom to provide some lube upon startup.. I save the wipe down with oil until last after all the pistons, top of the block, threaded holes have been scraped, tapped cleaned and dried. But like I said my method involves scraping.

[632 Regal]

All you need is some chunks of carbon or shavings (incase you use a tool) getting between the ring and seat land to temperarily or maybe perminently whack them out of shape.

Chemmies running between the rings and lands is another good way to loosen stuff that was not meant to be loosened while assembled. You can try if you want but dont complain if you lose some compression or start burning oil.

Ahhh... another good thing would be the chemicals running down and getting between the crank and bearings, that should do some good when you turn it over or eventually start it.

My recommendation if your going to go nuts with thinner or whatever is to have the engine on a stand and turn the engine so that the pistons point straight down, then you wont risk the chance of having it ruin a good running assembly.

Not giving you a hard time yet because I dont exactly if the engine is out of the car or not. Some carbon will not hurt anything if left alone especially if it is a very thin layer, in fact it will help reflect the heat back away from the piston resulting in a more efficient burn. Thick layers of oily carbon I agree should be removed.

While your at it, take a good look at the intake valves for a nice thick buildup of crud on the back side of the valves, that will rob more efficiency than carbon on the pistons AND a buildup of crud on the exhaust valves.

[Hector]

Hopefully, nothing will run down to the crankcase. I got enough common sense to stop something like this from happening. What I alluded to in Bill's reply was that if some chemical does run down through the cylinder, I'd have rags or something stuffed deep in the cylinder that is, on the crankshaft side, to catch the residual solvent from pissing downward. Nothing is going to get in the bearings if I can help it. Chemmies, chum, **** or whatever you want to call it, is not going to loosen anything if it doesn't go down there, right? I appreciate your concern.


All you need is some chunks of carbon or shavings (incase you use a tool) getting between the ring and seat land to temperarily or maybe perminently whack them out of shape.

Chemmies running between the rings and lands is another good way to loosen stuff that was not meant to be loosened while assembled. You can try if you want but dont complain if you lose some compression or start burning oil.

Ahhh... another good thing would be the chemicals running down and getting between the crank and bearings, that should do some good when you turn it over or eventually start it.

My recommendation if your going to go nuts with thinner or whatever is to have the engine on a stand and turn the engine so that the pistons point straight down, then you wont risk the chance of having it ruin a good running assembly.

Not giving you a hard time yet because I dont exactly if the engine is out of the car or not. Some carbon will not hurt anything if left alone especially if it is a very thin layer, in fact it will help reflect the heat back away from the piston resulting in a more efficient burn. Thick layers of oily carbon I agree should be removed.

While your at it, take a good look at the intake valves for a nice thick buildup of crud on the back side of the valves, that will rob more efficiency than carbon on the pistons AND a buildup of crud on the exhaust valves.

[632 Regal]

once when I was in high school I saw a dude tape off the top of his pistons and sandblast them. Should have seen that thing run at the high school nationals...drove there towed home...lmao. When he took it apart the only thing salvagable was the dipstick and intake manifold, even the carb had sand in it.

Rule of thumb, always sandblast at a friends house.

[winfred]

i've been known to use a die grinder with a soft compound 3m roll lock bristle disc, with a light touch

[632 Regal]

But not to an assembled engine.

[535ise]

I used diesel as a presoak to remove carbon on my piston's,it soften's the deposit's up so makes it dead easy to clean off.

Apply with a brush and leave over night

[632 Regal]

I used diesel as a presoak to remove carbon on my piston's,it soften's the deposit's up so makes it dead easy to clean off.

Apply with a brush and leave over night

[BMW-F1-FAN]

I used carb cleaner and scotchbite pads. Make sure to only contact the piston tops, don't touch the top of the block.

Here is a pic

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