What causes rust in a cooling system?

Posted on January 17, 2018 in Auto Repair

Discolored rusty coolant is typically indicative of rust in the cooling system. But what causes it? How can you prevent it? Here are a few things to take note of:

Lack of Proper Coolant

Using the proper coolant and antifreeze in your car is key. Don’t pour water into the radiator, as water will oxidize the system’s metal moving parts, eventually causing rust. Once metal parts rust, like the impeller and water pump, the lack of coolant flow through the engine block from the radiator can cause problems that are even more expensive to fix.

Air in the Radiator

Rust in the cooling system can also be caused by air getting into the radiator when the engine cools down. As the coolant cools down, it contracts which can cause an air pocket. An overflow tank (see the photo to the right) should have sufficient coolant in it to keep the radiator full even at cold temperatures but, without an overflow tank, air will enter the cooling system through the radiator cap as the coolant contracts. This can cause rusting, while also creating wear on the water pump’s seal and bearings.

At V&F

If there is rust in the cooling system it is best to flush the system and replace the old coolant with new fluids. Remember to have your coolant system inspected every spring or winter to ensure the coolant is to specification. Additionally, if you have to add water for emergency type situations, make sure to have a mechanic flush it out right away. At V&F, our expert mechanics use latest diagnostic equipment, and high-quality CARQUEST auto parts, to make sure we get the job done right. Call us today at (413) 314-2280 or schedule an appointment online.