Cleaning block

[37chief]

The coolant in my TO 20 was very rust colored. I drained it and refilled it a lot of times. I thought it was clean I put water in and ran it for about 15 min, and it is rust colored again. So anyone have a good suggestion on how I can get the block cleaner? I don't want to add antifreeze until I am sure most of the rust is gone. Stan
 

[Richard L]

I googled "clean a radiator and block" and there are many threads to help you out.
 

[Jason S.]

Add a gallon of white vinegar to water and run it.
 

[samn40]

Add a few spoonfuls of washing soda then run it for a few hours. Then flush it and do the same again until clean.
Sam
 

[mattwillson]

10 minute rad flush from kleen flo, or you could mix up borax and water. run it until hot, then dump it. when motor cools off refill with water to rinse, might want to do it twice.
 

[Bruce(OR)]

Once upon a timer I used Permatex radiator cleaner. It worked great! Hydrocloric acid in a 1 qt plastic jug. The next time or two later I did it to a cadillac diesel. It blew out the head gasket. I scrapped the $400 jalopy.
Rust in a coolant system can also be the sign of exhaust gases getting into the coolant.
Good Luck with your project!
 

[Inno]

If it was a 350 conversion diesel in that Caddy it was probably on it's way out anyway. You look at them things the wrong way and they pop a gasket! Parents had a Pontiac with one of 'em. I changed the head gaskets when I was 19 then they sold the car.