Calcium deposits on Radiator That Holds Pressure - Benzworld.org ...

You've probably seen me ask tons of questions about this in other threads, but I think it's worthy of its own now. I had this one pressure tested after the radiator guy said it needs to be re-cored. It holds, and is much better than the one I picked up at the JY. So rather than spending ~$680 (including shipping) from the online Mercedes dealer (a good price really), or $600 for a recore. I've decided that I'm putting this one back in the car until it fails.

I did some research on this one, and it appears to be a recore that was done prior to 1995. I called the radiator shop that put a tag on it with their tag number. I've never seen the radiator leak, and these have been called "sweat" deposits, and never called actual leaks. But everyone says that maybe under the right conditions they could start leaking.

The radiator guy verified that these are not leaks at the fins, which appear to be totally fine, just where the fins connect into the bottom of the core. The radiator guy also told me not to touch the deposits. They may be clogging existing holes, and it's not worth messing with them. The reason you don't want to try to re-sweat/solder/braise those copper joints is because the heat you create to braise one joint will open up leaks on both sides. So I'm not touching the calcium deposits, or heating up this radiator.

My question is this:
What do you guys think about putting POR-15 just over the joints where the fins meet the bottom of the core, encapsulating the existing calcium deposits? I would NOT put POR-15 on the radiator fins. That would kill the heat transfer.

Of course my handyman transferred my POR-15 to a plastic container and it not only hardened but ate through it. So I'll have to order some more. Or someone could tell me why this is a bad idea, and I'll just drop in the radiator as-is, and get the job done faster... or even a POR-15 substitute I could pick up locally.

P.S. Deposits are only at the bottom of the core-fin joints, not the tops. Hmm