Flushing out your radiator with water from a hose can be a good first step to address rust and other contaminants in the cooling system. However, if you are dealing with a significant amount of rust in the radiator, simply using water from a hose may not be enough to completely clean the system.

To effectively flush out the radiator and remove rust buildup, you may need to use a radiator flush solution. This product is designed to break down and remove rust, scale, and other deposits from the cooling system. You can typically find radiator flush solutions at automotive supply stores.

Before using a radiator flush, make sure to follow the instructions on the product label carefully. It usually involves adding the flush solution to the radiator, running the engine to circulate it through the system, then draining and flushing the system with clean water.

If the rust buildup is severe, you may also need to consider having a professional mechanic inspect the cooling system to determine the extent of the rust damage and recommend further steps to properly clean or repair the radiator.