Coolant Flush

So, you think you need a coolant flush? This is one of those DIY auto repair jobs that seems like it should be the easiest job ever, but can turn out to cost you a lot of money if not done correctly. This can be a simple auto maintenance task that you can do yourself if you know a few things about your cars cooling system. Let's take a look.

The Truth Behind Coolant Flushing

What you may have heard: "This is a simple job"... "You need to use chemicals to get debris out of the radiator" or "It can only be done at an auto repair shop"

The truth: You don't really need anything special to replace the antifreeze in your radiator. You need to be sure and get the right type of coolant and you need to be sure and use an auto repair manual so you know how to drain the radiator, how much fluid to put back in, how to bleed the system, etc. If you do any of these steps incorrectly you could have an expensive problem on your hands. 

If you want to do an actual flush of your cooling system then, yes you would need a special machine that is very expensive.

Coolant Flush vs. Drain and Refill

First we need to define is the term "coolant flush". Many people get this confused with "drain and refill". There is a big difference.

While a drain and refill is fairly straight forward and generally not difficult, a flush is much more difficult. A drain and refill generally only includes draining the radiator and reservoir then refilling it with new fluid. This is a fairly easy job for most people. Just make sure you have a plan for getting rid of the old fluid as you cannot just pour it down the drain or onto the street.

For most people a drain and refill periodically is all you will ever need. The only time I really recommend an actual coolant flush is if your radiator and cooling system has been contaminated by something (transmission fluid is a common fluid that leaks into the radiator). 

What Exactly is a Coolant Flush?

Here is what an actual flush entails; The best way to remove virtually all of your fluid is to hook your car up to a machine that removes it while putting the right amount of new fluid in. These machines can circulate the fluid through your vehicles cooling system a couple times which will remove any debris that might have built up over time. This is really the only good way to have this job done right.

If there is any debris in the cooling system (like if it has not been drained and refilled for 20 years!) then this is the only good way to get it out. Sometimes scale and other things will build up (especially if you use tap water to fill the radiator) and cause the radiator to become restricted. A flush will help to remove some of this. 

Now that you know the difference between the two you will be ready when you take your car to a shop to have your coolant replaced.

How to Do a Coolant Flush at Home

Do I Need Chemicals To Flush the Radiator?

There are many brands of special "flush fluid" that the manufacturers will say you should use to flush your cooling system. My professional opinion is that these are not needed. Especially if you drain and refill your cooling system at the intervals listed in your owners manual. These products are there to get you to buy more stuff. They are generally not needed.

If your cooling system has been abused (coolant never changed, using tap water, frequently overheated, etc.) then it can be a good idea to use some chemicals that will help to clean the system out. Most people that maintain their vehicles will never need to have this done. 

My Final Advice...

Drain and fill your cooling system regularly. You can find how often you should be doing this in your owner's manual. If you do this then you will probably not ever need to have a real cooling system flush done on your car.

Unless the scheduled maintenance guide in the owners manual says that you need to have a coolant flush done periodically (or your cooling system has been abused), then don't have it done. It's just another way for repair shops to squeeze more money out of you!

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