Re: CLR to clean out Engine Waterways

Posted by Owen_Dyneto On 2010/12/3 14:14:43

Lye (sodium hydroxide) is sold commercially in liquid form as a 50% solution, and packaged in plain steel drums so there is no need to be concerned about lye attacking cast iron or steel. But it is RAPIDLY and QUICKLY destructive to aluminum. A strong, warm lye solution can eat thru 1/4 inch of aluminum in minutes; in fact that's the basis for the alternative to machining on reducing the weight of aluminum parts, so called "chemical machining". OEM headgaskets for the V8 were steel shim so that shouldn't present a problem.

I still think the best common chemical to use for rusty systems that's safe on other materials is oxalic acid which can be bought in most hardware stores. It can solubilize ("chelate") iron oxides; but use a neutralizer like baking soda afterwards. I think we've covered the use of oxalic acid in the past on this site - a search might be beneficial.