Originally Posted by SJTD
Can you still by the two part flush? Was in a stacked can with oxalic acid in one and a neutralizer in the other. The acid component reduced the rust meaning converted it back to iron. This causes it to shrink and loosen up.
I read once that a molecule of rust is 10x the size of the iron molecule it started as so it shrinks a lot. I should look that up and verify now that info like that is so easy to find.
Oxalic acid is still available for bleaching wood, I think, even if not as a cooling system cleaner.
Hydrochloric acid, aka muriatic acid scares me as a flush agent.
You can put together the equivalent of the old 2-part kit. GM published a service bulletin on flushing coolant systems that you can find online if you search. You need wood bleach (oxalic acid) and washing soda (sodium carbonate). Both chemicals can be purchased OTC. I expect the 2-part kits were banned because of indiscriminate dumping of the waste water.
Oxalic acid combines with rust to form iron oxalate - basically turning the rust into an organic salt that dissolves in water. It's a mild acid that has to be safer for your water pump bearings and seals than muriatic acid - likely more effective too. There may be similar materials available today that are more environmentally friendly. The washing soda is a benign neutralizer.
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Last edited by tgreese : 09-08-2021 at 02:23 PM.