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In the owner's manual for my 2001 Ford F-150 (5.4L), in the section on "Adding engine coolant", it specifies the type of coolant to be used, and says it should be mixed 50/50 with distilled water. It explains how to open the coolant reservoir and so forth, and then there is the following paragraph (emphasis mine):

After any coolant has been added, run the engine for a few minutes to mix the coolant. Check the coolant concentration. Make sure the engine is off and cool before removing the coolant pressure relief cap (see proceeding [sic] steps on cap removal). Check the concentration per the Checking Engine Coolant section. If the concentration is not 50/50 (protection to -34 F / -36 C), drain some coolant and adjust the concentration. It may take several drains and additions to obtain a 50/50 coolant concentration.

The section on "Checking Engine Coolant" explains how to check the level of fluid in the coolant system, but in an apparent omission, does not actually say anything about how to check the concentration. I don't know how one would do that.

  • Short of a complete chemistry lab, is there actually a way to test the concentration of coolant in the system, to see whether it is 50/50 as specified?

  • Other than by somebody having added the wrong concentration, is there any reason why the concentration of coolant currently in the truck should become incorrect? Why would it be necessary to test it? (Differential evaporation rates, maybe?)

It seems like the question Is coolant testing necessary on modern vehicles? is also about some method of testing the coolant mix that's already in the vehicle. But I don't really understand what they are talking about, and it doesn't directly address my questions.

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Nate Eldredge
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2 Answers2

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In answer to the question of how to test your coolant mix, you would use an antifreeze and coolant tester

In answer to why, you would want to ensure that your coolant mixture is correct as this provides protection against icing in the winter, enhances the effectiveness of the system in the summer and provides some corrosion inhibitors to prevent your coolant system rusting or silting up inside.

Steve Matthews
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Testing Coolant is pretty easy using specific gravity. A tester has several balls that have slightly different densities. Different balls will float depending on the concentration.

You want to test your concentration to be sure it wont freeze or over heat. The Antifreeze does not transfer heat very well. That is why we mix. The water does most of the cooling while the antifreeze prevents freezing. Some southern states (warmer climates) will use lighter consentrations of antifreeze. This will allow the coolant to freeze at higher temps but also cools the engine better at very high temps.

In the end, Flush the coolant if your unsure. Testing only tests the reservoir. If your coolant is clean and bright green its likely fine. If your unsure testers are available at any auto parts store.

There are Red, Yellow, and Orange antifreeze's used on some vehicles. There is usually a note on the fill cover if they use these coolants only.

JpaytonWPD
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