Using CLR to flush a Brass Radiator

[expat]

I saw a guy doing this today, he had the Rad out to replace the water pump. While it was out he poured a jug of CLR cleaner in, and sloshed it around.
The muck that came out was impressive!
But,
Could CLR damage the core?

 

[Falcon_LS]

I've used CLR to unblock a clogged heater core. It's not exactly cooling system friendly, so you really want to keep it there for as short as possible.

For it to work properly, you will first need to flush the system so there is no coolant left in there, just plain water. Then wait for the engine to cool down a bit, and add the whole bottle of CLR.

Because CLR foams, you want to keep the radiator cap off. Turn on your heater, and let the engine idle with the rad cap off until the thermostat opens. Once it does, get the thermostat out and start thoroughly flushing the system.

 

[Lyman]

I used to use it to clean my cooling system years ago. Never had a problem. As a matter of fact it worked real well.

 

[Charlie1935]

I remember my Dad using Drano back in the 40'S.
Needless to say it got a good flushing after that.

 

[JMK]

I've used Lime-A-Way in older vehicles that were neglected. Remove the thermostat, flush with plain water, refill with water and a gallon of lime-a-way, run for 15 minutes. Flush many times until it runs clear then a few more times to be safe. Never a problem. Just remember most of these products react with aluminum so if you do use it maybe a neutralizing agent would be a wise idea in a newer vehicle.