legacycentral bbs

Hi Guys,

I was tooling around Alldata looking at some information for my WRX. I just happened to see a TSB or note regarding radiator/coolant flushing. I thought it was interesting as I had never heard this before.

"Do not use flushing machines.

If a flushing machine has been used to service other brand vehicles with copper radiators, a chemical reaction between copper ions and Subaru coolant may occur. This could also cause clogging of the radiator.

If regular flushing is required, only use fresh tap water. Do not use hard water. Hard water will create calcium build-up which will clog the radiator."

My WRX is an '03 but I'm assuming the OEM coolant is likely the same for our 1st gens. I've talked to a few people with 1st gens that had their coolant flushed. I felt the need to get this out there incase it has been an issue for anyone here.

Yeah the copper and aluminum can create a galvanic corrosion with dissimilar metals. (There's an interesting blurb in that link about "a lasagna cell")


The flushing with tap water....and it being "hard" water. I don't think it's as big a deal if all you're doing is flushing and you get all the tap water out. I wouldn't want to leave hard tap water in for extended period of time though.

Yeah the data sheet showed a pretty nasty picture of a sectioned radiator. It looked like 10 year old air filter from a residential hvac system

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