[Cougar429]

I have been working on engines for over 3 1/2 decades and can stand by the pure glycol/crockpot method. However, I set no time limits and in some cases have left them sit for 2 days or more, occasionally checking their condition. There really is no rush. Long term soaking does no damage to rubber parts but do not expect gaskets to last, even if the parts are assembled.

You also want to rinse the parts and oil them again right after rinsing and drying since if any ferrous bits they can begin to corrode almost immediately.

There are three warnings to be aware of: Only do this outside since the fumes can be toxic and NEVER use that crockpot for food prep at all in the futures.

Also, these parts will be HOT! I fabbed up a basket to fit the inside and can lift the parts or assemblies out without direct touching.

Found my pot at a resale shop for under $10 and filtering the glycol back into the container means it can be reused so the investment is low and can last indefinitely.

Although those that use the ultrasonic cleaner may have great results cannot confirm. May actually try it one of these days.

The glycol I use is the regular pure for standard engines. The new long life/aluminum specific blends will have additives to promote their properties and that may affect the cleaning ability.

On the subject of changing the color of the alloy, most engines I have seen have a form of coating to prevent corrosion and if removed the environment may attack the case material. Aluminum alloys can corrode, but pure aluminum slows that process to nil.

Floyd, I did have an engine case end up with black spots, but in that one instance had decided to soak the bits in methanol, (paint thinner sold in any paint department). Unfortunately was in a hurry and poured it into a coffee container that had not been rinsed out well enough. There were grains remaining from I suspect under the lip that flushed into the methanol when the lid was installed and agitated.

ps. On the earlier subject of lubing the parts, I use a 50/50 mix of air tool oil and trans fluid, (ATF) something I came up with many decades ago for assembly lube and After Run Oil. Either would likely work fine, I just tried it and the results were great. Again, the initial cost may be a few dollars, but this lasts nearly forever.

[floyd]

Floyd, I did have an engine case end up with black spots, but in that one instance had decided to soak the bits in methanol, (paint thinner sold in any paint department).

I've never heard of methanol being used as a paint thinner. Methanol is used to clean wood projects. The only thinners I know of are water for water based paint and Varsol or solvent for oil based paints. I do most of my engines by hand and have for as long as I can remember. I've never seen any issues cleaning with methanol.

My new after run recipe is a third red tranny fluid, a third Marval mystery oil and a third air tool oil. My own engines that I've done bearing jobs on years ago are all still perfect with no play and smooth bearings. Cheers Floyd

[kamlooper]

I heard of another method by a reputable modeler out this way, and that is to soak in kerosene. But ive never tried it.

[thatguy]

Scotch pad,break clean,oil and elbow grease worked good for me.

[stegl]

Years ago I used a cleaner for decarbonizing and cleaning VW air cooled aluminum cylinder heads and it worked very well . In fact so well that one time I had left a screwdriver in the screened pail that cane out with the handle dissolved over 12 hours . Don’t remember the name of it but you had to have a layer of water float on the top to keep from evaporating . Was safe on any metal. Quite expensive when buying a 5 gallon pail .
This may have been it :https://www.kleenflo.com/products/651-652-653.html
Currently pretty toxic stuff though :https://www.kleenflo.com/msds/651_652_653-1.pdf