Why Is My Coolant Orange? (7 Reasons Why)

What is that orange gunk in my car’s radiator? Maybe you’ve been wondering about this for a while. 

Maybe you haven’t seen it in ages but have noticed recently that it’s back, and you can’t figure out why. 

So, if this sounds like you, keep reading because there are some pretty good reasons why your coolant might be orange and what you can do about it!

Why Is My Coolant Orange?

An orange coolant can happen for several different reasons. First, it could be because of your faulty thermostat that does not shut off your engine, resulting in high temperatures and your coolant turning orange. In addition, an oil leak, bad water pump, or clogged water pump impeller can also be the culprit of this issue.

So, learn more about why your coolant is orange. Here are seven reasons why. Keep reading for more information!

1. A Faulty Thermostat

If you’ve ever gotten your car to run too hot, you may have noticed that your coolant color changed from clear to a dark orange tint. 

This is because the thermostat is supposed to shut off when your engine reaches its operating temperature. 

But if it doesn’t work properly, then your car will continue to run at high temperatures and burn up more oil and other fluids in your engine. 

You should take this into consideration before replacing your thermostat with one that works properly.

2. Oil Leak

Sometimes when an oil leak occurs, it can lead to the formation of an orange-colored liquid in your engine compartment. 

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This is because most oil contains sulfur compounds which react with oxygen molecules in the air and turn into sulfuric acid when exposed to sunlight or heat from friction inside an engine compartment.

3. Bad Water Pump

A bad water pump can cause coolant to seep out of a hole in it and drain into another area of the vehicle’s internal workings. 

Of course, it can become trapped indefinitely without spilling onto the ground or being noticed until enough time has passed for serious damage to occur over time. 

It could be anything from corrosion to rusting undercarriage components like suspension components or structural members like frame rails or subframe connectors.

4. Clogged Water Pump Impeller

Clogged Water Pump Impeller

Your vehicle’s cooling system consists of many different parts, but the most important is the water pump. 

It’s responsible for circulating coolant throughout your entire engine and delivering it to your radiator, where it can be used to keep your car cool.

Therefore, if this part becomes clogged, it will not work properly anymore, and you will notice that your coolant is orange instead of clear. 

That’s why you should have it checked as soon as possible by a qualified technician in order to avoid any serious damage or accidents that could occur while driving on the road with an overheating engine.

5. Corrosion In The Coolant Reservoir

The coolant reservoir is where the coolant is stored and is filled with antifreeze. 

Of course, the coolant reservoir can be easily corroded by water, acid, or other contaminants that enter the cooling system resulting in an orange coolant. 

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So, if corrosion occurs, it will reduce the ability of the car’s cooling system to cool down your engine. This can cause your car to overheat or even shut down completely.

6. Failed Injector

Injectors are like little pumps inside the engine that help to distribute fuel throughout the entire engine. They do this by pumping the fuel into the cylinders, where it can be burned by a spark plug. 

If they fail, then you will see an orange color coming from your radiator and possibly a puddle of coolant on your driveway.

The most common cause of injector failure is a low-pressure condition in the system. 

This usually happens when there is a leak in the cooling system or when there isn’t enough clearance between parts for proper circulation of coolant around all parts of the engine.

If you see a yellowish-brown or brownish-orange color coming from your radiator.

This means that your coolant has overheated due to poor circulation or low-pressure conditions in your cooling system. You should have someone take a look at this problem immediately.

7. Too Much Antifreeze

You’re using too much antifreeze in your radiator system if the color changes from clear to brown/orange after running without it for a while. 

Or if you’ve changed brands of antifreeze without changing their proportions (like adding more than 3 gallons per gallon). 

This can also happen when mixing different types of antifreeze—don’t mix them all together.


The reason for the color is harmless, and when you’re out of coolant, it’s obviously time to add some more. 

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It’s not a lot of fun to have a car that needs to be topped off all the time, but it beats the alternative. Make sure your coolant levels are good, and you’ll avoid unnecessary problems.

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