How to Flush a Vehicle’s Cooling System

Your car’s cooling system needs to be periodically flushed out to ensure maximum cooling results. It takes minimal work and tools on most vehicles to properly flush the system, and the results give your car a fighting chance in the summer’s heat.

You will need a standard flat edge screwdriver or possibly a pair of pliers, a fluid catching container, and a garden hose with water access. Additionally, you can purchase a bottle of cooling system Flush Out to help remove stubborn debris from the radiator and other cooling parts. The debris is rust and other deposits that come from boiling water and moving parts, like the water pump.

Also, depending on where the thermostat is located in your vehicle, you might consider changing it at the same time. Even if you believe the thermostat to be in fine condition, it is a fact that they need changed semi-frequently. Quite frankly, it just makes more sense to do it now instead of breaking down later with an over-heated engine. However, if the thermostat is not contained where the hose meets the water pump, then it might be better to replace the thermostat at a more suitable time or to put it in the shop. The reason why is that many of the newer vehicles are so compact and intricate that it is required to remove large portions of hardware to get to it.

When you are prepared, climb under the front of your car and look for a drain valve. Drain valves come in a variety of styles, but the most common seems to be an irremovable screw type of plug that releases the water when turned. When you have located the valve, place the fluid catcher directly under it and open the valve. Be careful not to let the fluid go into your eyes or mouth. If this happens, call 911 and start running water into your eyes immediately. After the fluid has been drained, remove the catcher.

Locate the hoses that belong to the cooling system. Although almost anyone can tell the difference between a cooling system hose and a air conditioner hose, if you don’t know the difference or are unsure, then please ask someone that knows. It is very easy to identify the hoses that come from the radiator, but it might be harder to identify the smaller ones.

With the screwdriver or pliers, remove the clamp and pull off the first hose. I prefer to remove the hose that runs from the water pump to the heating core first, then work my way down. Insert the garden hose into the hose and turn on the water. The water should come out the other end, so be prepared for a water spout. When the water is coming out clear, then simply move onto the next hose. I usually save the bottom radiator hose for last. After I remove it and begin running more water into the radiator, even more rust comes out. This is good though, because this is the stuff that slowly clogs and ruins the radiator.

Optionally, some people prefer to start the vehicle and run it for a moment during the water in-water out process. This does indeed help to push out rust and other debris, but if you are not used to doing car engine work then the risk of injuring yourself or damaging the engine increases. No matter what you decide on this method, always use great care and caution when working with fluids and running engines. And never, ever, try to remove a radiator cap while the engine is hot. The force and heat of the water will give you third degree burns along with other injuries.

After you have flushed the car, closed the drain plug and reattached the hoses, fill the radiator with fresh water. Start the vehicle and run it for a few minutes. Do not overdue it, but a small drive or slightly revving the engine will help to stir up any remaining debris or rust. Also pay attention to make sure that all hoses are replaced tightly by watching for seeping water. Let the engine cool down to a safe temperature and remove the bottom radiator hose again. You will notice that the water is not coming out very clean- and that is a good sign.

After the water has been completely drained, replace the hose and refill the radiator with a correct mixture of antifreeze and water. The correct mixture can be purchased in the same manner that full strength antifreeze can, so you can easily finish this step. You have just finished flushing your car’s cooling system, and now you can take a break and cool down yourself.