How To Change the Coolant In Any Car

What Is Needed
There’s only a few things needed to get this project done:
1) Coolant
2) Drain Pan
4) Turkey Baster (Optional)
3) Funnels (Optional)
You can find links to these products above!
Why Replace Your Coolant?
A maintenance item that is often overlooked when it comes to vehicles is the cooling system. Coolant can last 2-5 years or 30,000 – 100,000 miles depending on the type. Your manual will tell you the type and change intervals recommended by your manufacturer. Why do you need to change your coolant? Well, it becomes more acidic over time and loses it’s rust-inhibiting properties. Once your cooling system starts corroding, parts such as the water pump, radiator, thermostat, and hoses will all start to fail. This can lead to an overheating engine which we all know can be catastrophic.
No need to worry though! With a few simple tools and knowledge, changing your coolant can be achieved in a couple hours.
NOTE: Do not mix different types of coolant. Unless you are doing a complete flush, always put the same type of coolant into your vehicle that came out of it. Mixing coolants can create a sludge which will ultimately cause your cooling system to fail.
How To Guide
Draining The Coolant
Now that that’s out of the way, let’s get started. The first thing we need to do is drain the coolant from the engine. I’ll be changing the coolant on a 2000 Mercury Mountaineer so I will need to remove a plastic cover in order to gain access to the bottom of the radiator. This cover is just held on with 4 bolts.

Now that we have exposed the bottom of the radiator, locate the petcock. This the valve that will be used to drain the coolant. My petcock is located on the passenger side of the vehicle.

I’ll be draining the coolant into an open top oil pan. Using an adjustable wrench, loosen the valve and start draining the coolant. If you would like to speed up the process, you can open the radiator cap. This will let air into the top of the radiator making the coolant flow much quicker. The oil pan isn’t large enough to catch all the coolant but, I was able to close the valve half way through and transfer the fluid into milk jugs I had laying around. Repeat this step until your radiator is empty.

Once all the coolant is drained from the vehicle you can close the petcock. Alright, Hercules, no need to wrench on this! It’s just plastic. You just need to snug it down. We can now check the coolant reservoir to ensure it emptied when we drained the radiator. If if did not, you can use a turkey baster to remove the coolant from here. My reservoir is empty so I’m good to go.

Replacing The Coolant
So now that all the coolant has been removed from the vehicle, we can fill it back up. We’ll start by filling the radiator. I like to put a funnel where we removed the radiator cap. Fill the radiator until it is full. I also partially fill the funnel. This extra coolant will feed the radiator as we start working the air bubbles out of the system.

We now need to replace the coolant that drained from the coolant reservoir. I like to fill it up so that the level is somewhere between the cold and the hot line.

Alright we’re getting there but, we’re not done. We’re going to have air bubbles trapped in the cooling system. This is normal after replacing the fluid. The easiest way to free up this air is to start the car. This will kick on your water pump, circulating the coolant throughout the engine. It will push the air to the highest point which is the top of the radiator, where our funnel is. As the car runs, you will notice air bubbles coming out of the funnel and the coolant level in it will drop. Keep adding coolant to ensure the radiator stays topped off. We want to let the car run for several minutes until there are no more bubbles coming out of the funnel. A trick you can use to help with the process is to squeeze the upper radiator hose. This is a larger hose that comes out of the top of the radiator. Squeezing this helps move the air bubbles around, and hopefully out of your engine. CAUTION: the upper radiator hose is usually close to the fan. If you plan on squeezing the hose with the engine on, be extremely mindful of where the fan is so you do not catch a finger in it.

Once you are confident you got all the air of of your cooling system you can now take out the funnel and close the radiator cap. Don’t be that guy and put the radiator cap on with the label upside-down! Check the level in the coolant reservoir one more time and you’re all done! As you drive the car around for the first few times check the coolant level in the reservoir. It is possible that more trapped air bubbles will work themselves out and cause your level to be low. Top it off if needed.
Now that wasn’t so bad, was it? You can now live your life knowing that your cooling system has been taken care of and you won’t have to worry about that old nasty fluid destroying your cooling system, blowing your engine, and costing you thousands.