Engine coolant flush-filtering using external gas pressure and radiator valving

In the method of treating coolant liquid in an internal combustion engine cooling system, the steps that include:

• (a) forcing the coolant liquid from the cooling system to the exterior of that system,
• (b) treating the coolant liquid in a zone or zones outside the cooling system, said treating including removing contaminant from the coolant liquid, and
• (c) returning the treated coolant liquid to the cooling system,
• (d) said forcing step including supplying a pressurized gas to the cooling system to drive coolant liquid therefrom,
• (e) the cooling system including a heat radiator including a container having a coolant liquid fill opening, and a valve controlled discharge port proximate the bottom of the radiator, and said forcing step including employing said gas to drive coolant liquid from the radiator via said discharge port, and
• (f) and controllably venting fluid, including gas from said container via said fill opening, during said step of returning the treated coolant to the cooling system.