piston cleaning

[llwood]

ok i have the engine down to the short block and there is alot of carbon build up. What is the best way to clean this? I am leaving the bottom end intact and changing everything above that so....

[Jeremy]

Try GM Top Engine Cleaner. It'll easily dissolve that stuff.

[fuquefrance]

OK, I assume when you say you are "changing everything above that" you are completely replacing, heads, intake, etc...so the carbon you need to clean is only in the block, and you don't need to clean it on the ports, barrel, head pipe, intake, or on top of bore cause it's all getting dumped? Right? I'll assume you want to clean the bottum end. Bare with me...

And I assume when you said you have alot of carbon means that simple solvent will NOT remove it all. You’ll never be able to completely eliminate the presence of carbon. To clean the piston, both the dome and the ring land must have the crud removed. Check in the area where the plug would be firing and look for any corrosion of the metal. This’ll give you a good idea on how the motor burns. If the area is pitted, the piston should be replaced and the timing checked.

All carbon from the top of the piston can be removed by using a razor blade, the single edged variety, and scraping the dome until all of the carbon is removed. There are two good methods for doing this. Either use the blade as a cutting edge and slowly carve the carbon down by pushing; or use the blade as a scraper and run it straight up and down, moving it back and forth quickly. All of the carbon will come free using either of these methods, the latter being faster.

When doing this, be careful not to carve on the piston. Any cuts or scratches will cause hot spots, and in the long run, trouble. If you happen to scratch the top of the piston, get some 600 wet-or-dry sandpaper and buff off all of the scratches. DO NOT sand on the piston with paper any coarser than 600. It’ll make the situation only worse.

Once the top of the piston is done, clean the ring land. Any old ring for the same kind of piston works great. It doesn’t have to be the same bore size, since all you need is a section of the ring. Take the ring and sharpen one end on a grinder. Give it the shape of a chisel. Run the ring all around the ring land until the land is free of all carbon.

Use the ground ring in the position that fits into the piston; this way, the area around the ring will be the cleanest. Try not to remove any metal from this area. If the ring land is larger than the section of the ring, the ring will start to rock in the piston and will soon break.

The inside of the ring, where it sits against the dome of the piston, should be cleaned also. Use the section of the ring used to clean the piston for this. Keep scraping until there is no more build-up in the ring. Check the outside area of the ring for scuffing, or scratches. If the ring looks damaged, it must be replaced. Also, check the end gap of the ring in the cylinder before reinstalling.

Now wash it all with GM top engine cleaner to make sure that none of the carbon is left. Any debris left inside will work on the motor just like a handful of dirt. Now if you meant that you need to clean carbon on the top end, well just specify that and I'll give you some more pointers. OK?

[MonteC]

do not use razor blades.


ll, just go with jermeys advice. this guy up here is recommending something that will take way to much work.

[fuquefrance]

It's not too much work if it makes the engine run to it's maximum potential. He has the freaking engine torn apart. I'd bet that is a helluva lot more work than scraping carbon off pistons.

[fuquefrance]

And no, simple solvents are not going to eat away thick carbon deposits. He didn't say he had "some" carbon, he said "alot". that's why I told him to scrap it.

[nightrider]

engine down to the short block means he's not taking the pistons out.


i'll solve any carbon problems with water injection *yay me*

[MonteC]

Originally posted by fuquefrance
And no, simple solvents are not going to eat away thick carbon deposits. He didn't say he had "some" carbon, he said "alot". that's why I told him to scrap it.


its not a "simple" solvent u jackass. the stuff jermey recomended will take care of his carbon problem.

[llwood]

ok thanks guys