Rust build-up inside your radiator is an age-old problem that occurs primarily because of the nature of how your coolant system functions, and partly because of the make-up of some radiators. Some radiators are made with more metal and metal-based alloys that simply produce rust, due to the fact that they are constantly filled with a water and coolant mix. However, your radiator also circulates water through your engine to keep it cool. This too can cause rust build-up inside your radiator. Fortunately, there are special products made to remove and inhibit the spread of rust throughout your radiator. These products should be used when you flush your radiator.
Make sure your car or truck has completely cooled, then open the bonnet and remove the radiator cap.
Access the drain plug at the bottom of your radiator and remove it with a socket set or a pair of pliers.
Allow all the old coolant and water to completely drain out of your engine.
Read the instructions on the radiator rust remover and inhibitor product you have purchased. There are a number of different products that are sold on the market that remove and inhibit the spread of rust inside your radiator. However, directions for use will vary slightly with each product, so it is important to follow the exact directions of the product you have bought. Almost all of these products, however, will call on you to flush the radiator out thoroughly before adding the inhibitor.
Replace the radiator drain plug and fill your radiator with water. Open the drain plug again and allow the water to drain out.
Place the hose into your radiator and turn it on. Allow the hose to run unimpeded through your radiator for approximately 20 to 30 minutes.
Replace the drain plug and follow the instructions for inhibitor use. Some of these products will call on you to place the inhibitor into the radiator, add water and allow this mix to sit inside your radiator for a prescribed amount of time. However, other products may instruct you to add a half-and-half water and coolant mix, and then add the inhibitor to this mixture, similar to the way you would add a gas additive to your fuel tank.