Decarbonizing a disassembled engine?

What's the best way to decarbonize the pistons and head (valves and chamber) on a disassembled engine? Use a wooden or plastic scraper? Is there a chemical to make it easier? Thanks for any help from anyone who "has the T-shirt." :mrgreen:

A good quality brass scraper sharpened with a file works real well. For the narrower places a lengh of copper wire (rectangular) found in junk yards from old motors works well just flatten one end with a hammer and re-sharpen with a file. If you sharpen for two edges instead of one you can flip it over to get double life from each time.

A Dremmel tool with either the #536 brass brush or #404 nylon brush. The nylon ones wear quickly, you'll need a few of them. Carb cleaner spray and a red Scotch pad works too but it's slow going.

Huffer said:

What's the best way to decarbonize the pistons and head (valves and chamber) on a disassembled engine? Use a wooden or plastic scraper? Is there a chemical to make it easier? Thanks for any help from anyone who "has the T-shirt." :mrgreen:

Click to expand...

What about using oven cleaner? I read about using this to clean cylinder heads and pistons somewhere but was wondering if it was safe for use on alloy engine parts. Any perceived problems with it? Does anyone have any knowledge and/or opinions about this?

I'm thinking the sodium hydroxide found in some oven cleaners would be tough on aluminum. Might be okay if it's not left on to soak for a long time.

littlefield said:

I'm thinking the sodium hydroxide found in some oven cleaners would be tough on aluminum. Might be okay if it's not left on to soak for a long time.

Click to expand...

Yeah, spray on, let sit, wipe off. Anyone tried it?

Greetings,
I tried some "Easyoff" oven cleaner on some engine cases years ago, big mistake, it darkened the aluminum so I'll never try that again. For pistons, if the carbon is thick, I clean the tops with the wire wheel on my bench grinder (quick and easy). For ring grooves and the rest I have a small blasting cabinet (glass media), they come out just like new. With the combustion chamber, a small cup shaped wire wheel on an air die grinder makes quick work of it, and if the head is completely disassembled (IE valves, rockers, etc. out) I throw that into the blast cabinet also, gets right into the exhaust ports and other tight places quick and easy. Any parts I put in the blast cabinet I give them a good hot wash with soap and water right in the shop sink, then blow dry afterwards (put some oil on iron parts before drying).

GB

tpeever said:

What about using oven cleaner? I read about using this to clean cylinder heads and pistons somewhere but was wondering if it was safe for use on alloy engine parts. Any perceived problems with it? Does anyone have any knowledge and/or opinions about this?

Click to expand...

I've regularly used domestic oven cleaner (scrubbed with a scotch pad) to do the final clean-up on piston crowns, ring grooves and cylinder head combustion chambers without any problems, but it will still be necessary to scrape away the worst of the hard carbon first.
I've also used it to clean the outside of engine castings to remove oil stains and grime etc. and it has never dulled the surface of the alloy.

L.A.B. said:

I've regularly used domestic oven cleaner (scrubbed with a scotch pad) to do the final clean-up on piston crowns, ring grooves and cylinder head combustion chambers without any problems, but it will still be necessary to scrape away the worst of the hard carbon first.
I've also used it to clean the outside of engine castings to remove oil stains and grime etc. and it has never dulled the surface of the alloy.

Click to expand...

Thanks LAB. Maybe it's a matter of not leaving the cleaner on the parts for too long. I have some Guzzi pistons that need a clean up and I am going to give it a try.

Oven cleaner is somewhat commonly used on Goldwings with high mileage. It ruins paint but wing cases are apainted anyway. I do the same thing George does myself.