potassium hydroxide

Get it at your local candle / soap making store.

It will probably pit and discolor the metal.

And it will take your skin off if you dont wear gloves when handling it.

http://en.wikipedia.org/wiki/Potassium_hydroxide

Material safety data sheet.
http://www.jtbaker.com/msds/englishhtml/p5884.htm

RichC,
Potassium Hydroxide should not be used on Alloy. It is highly corrosive to it. You can get an instant reaction. It will eat away the head quicker than it will dissolve the crud.

There is nothing to worry about.
 

The problem is caused by leaky WVO from the return lines. The WVO has polymerized and became rubberized after contact with AIR. It is futile to try to dissolve with solvent. It will work but it will take a lot of solvent. You need to scrap it off.

This is what I did - remove the injectors and plug the hole with a small rag. Scrape everything from around the hole and try not to let and debris fall into the hole. That is the rag is for. Vacuum everthing off. Spray with WD40 to clean off the rest. You can do the same with the injector or soak it in gas. It would disolve all polmerized WVO. The inside of the engine should be OK if the WVO was fully combusted. The engine should be in reasonable shape since there is no smoke or a lot of blow-by. Change the return lines and you are good to go with diesel or alternate fuel again.

BTW: you can scrap it off without removing the injector. It is just a bit more time consuming.

Good luck.

depends on the alloy your talking about.

but in most cases i will agree potassium hydroxide will react with just about anything.