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De-carbonizing Heads and tops of Pistons


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  #1  
Old 02-19-2014, 08:40:53 PM
tdarden tdarden is offline
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Default De-carbonizing Heads and tops of Pistons

Looking for some inexpensive things I can do to a 5.0CCK in really bad condition while I wait on a few parts to try and get it running. I ran across a post of someone who "de-carbonized the heads " of a smaller Onan gen. I popped the head off of mine and indeed there was a huge carbon build-up on top of the pistons as well as the heads.

Is this something I can clean with some elbow grease and ?????? or is this machine shop stuff. Also the piston tops.

If this can be done myself what is the procedure and tools/products necessary. Any thing I need to pay close attention ....NOT TO DO ?

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Old 02-19-2014, 08:44:41 PM
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Billy J Shafer Billy J Shafer is offline
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Default Re: De-carbonizing Heads and tops of Pistons

Just get a soft wire wheel brush that mounts on a drill. Guide it over the head with just enough force to break up the carbon.Same with the piston
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Old 02-19-2014, 08:53:13 PM
tdarden tdarden is offline
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Default Re: De-carbonizing Heads and tops of Pistons

Thank you sir
Sounds like a snap !
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Old 02-19-2014, 09:08:13 PM
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Default Re: De-carbonizing Heads and tops of Pistons

Just be prepared to get dirty.
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Old 02-19-2014, 09:09:43 PM
BlkBeard BlkBeard is offline
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Default Re: De-carbonizing Heads and tops of Pistons

There are Scotch Brite Pads that go on a mandrel with a 1/4" shaft.

They fit in a 1/4" Air Angle Grinder or a drill if you don't have a grinder.

They come in course or fine and work great for cleaning carbon, removing pieces of baked on gasket etc.

You can find them at your auto parts store, Ebay, etc.

They're about 1-1/2" diameter

Here's a sample chosen at random
http://www.ebay.com/itm/3M-Scotch-Br...ecc953&vxp=mtr
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Old 02-19-2014, 09:45:59 PM
rmchambers rmchambers is offline
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Default Re: De-carbonizing Heads and tops of Pistons

Don't scour up the mating faces where the head gasket goes nor the bore of the cylinder. For areas where the brush can't reach I've sharpened a 1/2" wooden dowel into a point and a screwdriver shape and use that to scrape the gunk out. It's softer than the aluminum so it won't gouge it up. If you use the scotch brite afterwards but a little metal polish on it and buff up the heads and piston to a nice shine.. it will make it that much harder for the carbon to stick next time.

Take pictures too or we won't believe you.
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Old 02-19-2014, 09:48:38 PM
len k len k is offline
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Default Re: De-carbonizing Heads and tops of Pistons

Also clean carbon from arround valve seats and arround them with valve open, so it can breath better. I use a wood popcycle stick, with end ground to flat edge , like a paint scrapper.
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Old 02-19-2014, 10:26:51 PM
yellowlister yellowlister is offline
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Default Re: De-carbonizing Heads and tops of Pistons

i use scraper type tool.. think of it as a flat head screwdriver an inch wide only machined down on one side. works really good for the flat spots and not as messy as chemicals or wire brush.. and a small flathead for smaller areas.. just dont push to hard if u use one... after that some starter fluid and rag or paper towl and compressed air and its as good as new.. good time to check the valve seating and ammount of play in the valves and pistons and if any scoreing is in the cylinder bore.
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Old 02-19-2014, 10:40:42 PM
len k len k is offline
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Default Re: De-carbonizing Heads and tops of Pistons

I've also used a putty knife and a butter knife with tip sharpened to a flat putty knife. But guys here told me the resulting scratchs will make it carbon up faster next time.

On small engines (snowblowers & ect) I also reuse head gasket, no problems.
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Old 02-20-2014, 02:53:33 AM
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Default Re: De-carbonizing Heads and tops of Pistons

If the engine has sat a while, squirt some penetrating oil around the area where the piston rides in the cylinder. This will help un-stick the rings in the ring lands.
On my old '72 cck that had sat a while, I also very lightly scuffed up the cylinders to break the glaze in them. The engine doesn't smoke at all.
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