Climbing over the Rockies

n4hwl wrote:
Brett

I wash my radiator about 2 times each year. I usually use simple green and I have at times uses dawn. I heat up the engine and spray the cleaner on from the inside and let it sit a while. I wash it out from the outside with the hottest water my water heater will give me after I turned it up to the hottest setting. I have a power sprayer I can turn down to a low enough setting that will not hurt the fins and that seems to work well with this hot water. I repeat this process till I see no more dirt coming out. It is really hard to see down past the fan from the inside and see those bottom corners to see if they are clean.

Ken

I hope you mean Simple Green Extreme. The regular Simple Green is not to be used on aluminum and if you let it sit on the surfaces for more than 10 minutes, and did not rinse it off 100% out of all cracks and crevices, it will start to corrode the aluminum fins in your radiator.
From the factory FAQ section:
The aqueous-base and alkalinity of Simple Green All-Purpose Cleaner can accelerate the corrosion process. Therefore, contact times for unprotected or unpainted aluminum surfaces should be kept as brief as the job will allow - never for more than 10 minutes. Large cleaning jobs should be conducted in smaller-area stages to achieve lower contact time. Rinsing after cleaning should always be extremely thorough - paying special attention to flush out cracks and crevices to remove all Simple Green product residues. Unfinished, uncoated or unpainted aluminum cleaned with Simple Green products should receive some sort of protectant after cleaning to prevent oxidation.