Cleaning Pistons
Thread Starter
Instructor
Joined: Jun 2006
Posts: 172
Likes: 0
From: Seattle WA
Cleaning Pistons
I've got my heads pulled off and I need to clean the surface of the pistons to inspect for damage from valve contact. What should I use to do this that will be safe for the sleeves and not leach into the bottom end?
Le Mans Master
Joined: Jul 2005
Posts: 5,328
Likes: 405
PS You should be able to see any contact/damage on top of the piston easier before you remove the carbon deposits. It's difficult to see cracks in the piston with the naked eye and it's what you can't see that you need to be worried about. If there was contact and you have the stock pistons, I'd strongly consider changing the pistons if there was a broken/bent valve.
Pro
Joined: Jun 2005
Posts: 597
Likes: 43
From: Massillon OH
If you are asking how to clean the carbon off the tops of the pistons you could try using brake clean on a shop rag. Just be careful not to leave pieces of shop rag around the edges of the pistons. Realistically, if your valves hit the pistons you would not even need to clean them to see the damage. Just look for the shiny areas that would be partial or complete circles the same diameter as the valves. Good luck with the tear down and repair.
Safety Car
Joined: Jun 1999
Posts: 3,570
Likes: 3
From: Austin, Singapore, Kuala Lumpur, Houston, Dallas, Hong Kong, Elgin, etc.. Texas
Soak a corner of a rag with lacquer thinner and wipe away the carbon deposits, it's amazing how well it works. I'd bring each piston up to TDC to clean it though and make sure you wipe the cylinder walls down with oil after you're finished. The lacquer thinner won't hurt your sleeves but it will remove all oil residue leaving a nice place for rust to form.
PS You should be able to see any contact/damage on top of the piston easier before you remove the carbon deposits. It's difficult to see cracks in the piston with the naked eye and it's what you can't see that you need to be worried about. If there was contact and you have the stock pistons, I'd strongly consider changing the pistons if there was a broken/bent valve.
PS You should be able to see any contact/damage on top of the piston easier before you remove the carbon deposits. It's difficult to see cracks in the piston with the naked eye and it's what you can't see that you need to be worried about. If there was contact and you have the stock pistons, I'd strongly consider changing the pistons if there was a broken/bent valve.
Brake clean would also work but it evaporates faster.
Thread Starter
Instructor
Joined: Jun 2006
Posts: 172
Likes: 0
From: Seattle WA
Thanks for the tips. There clearly was impact, the valves are bent slightly and a few pistons are nicked. I want to get a better look at the surface of the piston with a high resolution camera to see what is visible.
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Pro
Joined: Nov 2005
Posts: 531
Likes: 11
Solvents are my thing
One of the best cleaning solvents I have used is starter fluid. Evaporates very quickly and really cleans well. Of course it is explosively flammable, but man, that stuff works! Pure ethyl ether I think it is. Brake Cleaners work good too, used to be perchloroethylene, but since they started engineering fluids for environmental purposes, you just don't know what it is going to be made of. All the best solvent materials have been replaced with green substitutes for our good health unfortunately.
Actually gasoline contains just about every sovlent type molecule under the sun, so whatever is designed to resist gasoline should resist any normal solvent. It's the plastics and paint that you have to be careful about melting away.
John
Actually gasoline contains just about every sovlent type molecule under the sun, so whatever is designed to resist gasoline should resist any normal solvent. It's the plastics and paint that you have to be careful about melting away.
John
Safety Car
Joined: Jan 2006
Posts: 4,598
Likes: 78
From: Miami FL
2020 C6 of the Year Finalist - Unmodified
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15-'16,'17,'18-'19-'20-'21-'22
Don't tell the guv'mint, but here in FL we can STILL buy brake cleaner with perchloroethylene. Works great for getting gravy stains out of neckties, too, since it is straight dry cleaning fluid.
Le Mans Master
Joined: Jan 2003
Posts: 8,596
Likes: 19
From: Portland Oregon
Forget carb cleaner, lacquer cleaner, brake clean......go the the auto parts store and get some permatex liquid gasket remover. Spray a generous amount on the pistons, let it soak, and then wipe the carbon off, you may need to repeat this a couple times if the carbon is thick. Or it wil soften it off well enough so that you can use a single edge razor blade to GENTLY remove the rest. Finish off by using Carb Cleaner to remove any residue, spray it around the piston edges using the spray tube, and then using a blow gun around the piston and a rag to prevent blasting it into your eyes or your body blow it clean. Apply a light coat of WD40 or the like to protect the cylinder walls.
Le Mans Master
Joined: Jul 2005
Posts: 5,328
Likes: 405
It'll be the cheapest insurance you've ever bought.
BTW I've tried all of the fluids named above plus mechanical cleaning (wire wheel/drill motor), the lacquer thinner worked the best. I cleaned the top and ring lands of 16 pistons in less than 45 minutes...as soon as the lacquer thinner hit the carbon deposit, it melted away. It was like hitting frozen butter with a blow torch.
