MTFCA Forum

I just put white vinegar my radiator to clean it. How long should it be left in?

Hi Bruce, it depends how crusted up it is. Domestic vinegar is not too strong so anywhere from a couple of hours to over night I guess. Flush well when done.

To start a controversy, an old timer trick was to add 1/2 cup of water soluble cutting oil to the radiator when refilled. I guess modern antifreeze additives may work too.

I leave it overnight up to 24 hours!

Then drain off enough to see the tops of the tubes. Save it. If clean, you're done.
Not clean, put the drained off stuff back in. Let her cook longer until it is.

It'll take me 3-4 days of soaking really crusty bolts and nuts in white vinegar to get the crud to release.... haven't ever put vinegar in a radiator yet....

White Vinegar (aka Cleaning Vinegar) comes in a variety of concentrations. 5% acidity to 30% is available at Home Improvement stores, 45% is also available. I have used 10% on a gas tank and it did such a good job, overnight, on one rusty spot it created a pin hole. I use 30% on rusty parts., usually 1/2 to 1 hour is enough. There is always a residue left on the parts that needs to be cleaned off so flush aggressively. The cleaned steel parts will oxidize quickly so be ready to add you coolant mixture. I'd drain a bit out of the radiator and check the color from time to time (about 1/2 to an hour apart) until there is no change significant change in color. The drained vinegar can still be reused on rusty parts several times , even when it looks dark brown, so don't pitch it.