How to Change Coolant

Besides the oil change, coolant replacement is the most important change you do for your engine. As you probably know, the good shape of the coolant fluid has a direct impact on proper engine work. Not enough or “worn out” coolant can cause overheating and that leads to head gasket failure or other major repairs.

Also, if you live in places with harsh winters, when the temperature drops a bad coolant fluid goes frozen causing in the worse case, engine block crack-age. If you can’t remember the last time you changed the coolant fluid, you can buy (in almost any car-part store) a coolant gage which shows you the shape of the fluid (minimum temperature, density, etc.)

Checking and Changing Coolant Fluid

Do the measurement first and if it’s time to change the coolant don’t wait on it. Buy quality coolant (with inner engine block protection) and look into the factory manual on how much coolant goes into the car. Buy an extra bottle, just in case.

The tools you’ll need to do the job are:

1. A multi-purpose screwdriver (has attachments for all kinds of screws)
2. A pair of commonly used plyers
3. A set of wrenches
4. A container that you can catch the old coolant in.

Important: Don’t under any circumstances do this while the engine is hot!!!! You risk bad injuries to yourself (severe burns) caused by the hot coolant.

Flushing the Old Coolant

You can flush the old coolant in two ways :

1. find the flush-screw on the engine block where the manufacturer has meant the coolant to go out. Unscrew it with a proper wrench and let the old coolant out.
2. you can flush the system by taking off the hose that’s in the lowest point of the coolant system. Just loosen the tightening ring that holds the hose (with a screwdriver), take the hose off and let the coolant out into the container.

Both methods are OK but we advise that you use the second one. The flush screw in many cases is hard to unscrew (due to corrosion and heat) and you risk breaking it off. That goes double for older cars.

In the second method, you’ll probably be able to take off the hose easily. Some old coolant will stay in the engine but this doesn’t pose a risk. Once the engine has cooled down and you’ve prepared the tools you do the next:

1. prepare the container for the old coolant and put in a position under the hose where you are going to flush.
2. loosen the tightening ring holding the hose (flush screw in method) with a wrench or a screwdriver
3. take hold of the hose and slowly pull it off the installation pipe (watch out, the system is under pressure!!)
4. let the coolant go out into the container. Open the coolant bottle cap.
5. Wait until all the coolant has flushed out.
6. put the hose (or screw for method A) back in place and tighten the ring (screw).
7. pour the new coolant into the system through the coolant bottle until the level is on maximum (measure on the bottle)
8. put the cap on the bottle, don’t tighten it. Leave it loose, so that air that got into the system while flushing can get out!
9. start the car and let it run. The point of this is air-venting the system (the cap on the coolant bottle is still loose). Watch the temperature gauge.
10. when the radiator fan starts to work in full throttle, that’s a signal that the system has proper circulation. Let the car run for a few more minutes and then turn off. Tighten the cap on the bottle and check for possible leaks.

Make an additional check as soon as possible (perhaps the next morning) and, if needed, add coolant.