Cheap, Easy Ways to Check Your Equipment’s Coolant


With 40% of engine failures on heavy equipment due to coolant issues, it makes sense to keep on top of the fluid’s condition.

Fortunately, as we learn on this week’s episode of The Dirt, it’s easy, simple and doesn’t cost much at all to keep tabs on your machines’ engine coolant. Our guest, Shelly Eckert, Chevron Lubricants business consultant, details how that’s done, taking the guesswork out of this often overlooked, yet vital fluid.

Eckert runs down the types of tests you should perform on coolant and how to do them. You might be surprised to learn there’s a better way than using a hydrometer. She also explains how to use pH strips and answers common questions, such as when to flush the coolant, how often it should be tested and how coolant should look.  

With her guidance, you’ll be able to catch problems before they arise in the field and keep your equipment running in top condition.

So to find out more about how to maintain coolant, check out the latest episode of The Dirt.

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In This Episode:

  • 00:00 - How to Test Coolant
  • 00:28 - What’s the Most Important Coolant Test?
  • 02:05 - How to Know the Proper Water-To-Glycol Mix
  • 03:03 - Why Use a Refractometer Instead of a Hydrometer?
  • 04:59 - What is the Purpose of Organic Acid in Coolant?
  • 06:28 - How to Adjust Coolant When the Freeze Point isn’t Right
  • 07:32 - What Does pH in Coolant Tell You?
  • 08:53 - What Happens if the pH of Your Coolant is Wrong?
  • 11:48 - Why it’s Sometimes Best to Flush All Your Coolant
  • 13:23 - How to Use pH Strips to Test Coolant
  • 14:19 - How Often Should You Test Coolant?
  • 15:19 - Should You Send Coolant Samples to a Lab?
  • 16:33 - What Should Your Coolant Look Like?
  • 18:00 - Organic Acid, Nitrate and Multi-Use Test Strips
  • 18:51 - Final Thoughts


Bryan Furnace (00:00):

Today we're back to talk again about coolants, except now we're going to get a little more granular. We're going to talk about what sort of tests we should actually be performing and what these tests are actually telling us about our coolant. Without further ado, let's turn the interview over to Shelly. The first question, I guess, for a rookie who knows nothing about testing coolants, what sort of tests should I be running on my coolant outside of just checking to make sure it doesn't freeze?

Shelly Eckert (00:41):

Right. Well, the number one physical property is the amount of glycol or water, right? And the way that you test that is using a refractometer, which is exactly the same laboratories use that tests the coolant samples when they're sent into the lab, the exact same thing. You can get it off of Amazon, you could probably get at any of the parts stores. It's very simple to use. They're not that expensive, but they're very accurate. You just have to make sure that there's a water line in here because water freezes at 32 degrees Fahrenheit. To check it, and you just put a couple of drops of water here, close the lid and go to a light source so you can read inside of it. That also is dependent upon, which we haven't talked about, which concentration you're starting with. Typically 50/50 is what's sold, but some of the factory fill could be 55/45 60/40, 40/60, all depending on where you're at temperature wise, right?


The colder you are, the more you want it to have the glycol. The warmer you are, the less glycol you need. And as we previously have talked about in Hawaii or the Gulf, you really just use water and sometimes there's just an organic acid added to that water without having the glycol.

Bryan Furnace (02:04):

Interesting. Two questions that are going to come out of that. My first one is if I'm not sure what my mix is, is there some way that I can kind of figure that out? Is the refractometer going to tell me that? How do I kind of know what my baseline starting point is?

Shelly Eckert (02:18):

You start with what you're buying, right? And then if the decal on the equipment says factory filled with 50/50, then that's what your target is. A lot of times what I see with equipment, sometimes the OEM may or may not know where that equipment's going to go. It might be starting as a 60/40 perhaps just to cover it so that if it goes up into Canada that they've got plenty of glycol in there. Typically, when we train on freeze points, we let the guys know it's minus 35, plus or minus 15 degrees Fahrenheit. You want to stay within that window, which covers exactly what we were just talking about. If it's outside of that window, you need to figure out why.

Bryan Furnace (03:01):

Okay. And so my next question is why the refractometer over your bubble float hydrometer, whatever you call them?

Shelly Eckert (03:11):

Hydrometer. Actually, I was guest speaking last night, and this very same question came up and we were talking about it and I said, "Well, what happens is that when you get oil into your cooling system and then you take that hydrometer and go down and suck up the coolant into the hydrometer, you're sucking oil up into it as well." And as soon as you do that, those floating balls start to deteriorate because they're getting oil attached to it. And then within the hydrometer, it's starting to deteriorate and break down. One of my best stories about this is I was in a shop and I asked the guys, how are you measuring the freeze point? And all four of them came up with four different hydrometers. I said, okay, let's play a game. Let's take all of these over to this truck over here. We'll use the refractometer and we'll compare it to what the hydrometers are saying. And the hydrometers were various ages and you could see that they were starting to deteriorate.


The fairly new one was pretty close to what the refractometer was reading. Of course, I calibrated mine, so I knew it was accurate. And then the other three were all different.

Bryan Furnace (04:19):


Shelly Eckert (04:21):

I had the guys just throw them away and use the refractometer. If you're basing it off of a hydrometer that's not reading correctly, then you're going to be doing something that's just not necessary for the coolant. Coolant can be expensive. It's designed to have longevity. You've got to know what you're starting with because as we have previously talked about, there's various types of coolant. There's the conventional fully formulated extended life coolant that is a nitride organic acid, a hybrid organic acid technology, phosphate organic acid technology, and then of course the nitrate free organic acid technology.

Bryan Furnace (04:58):

What is the purpose of the organic acid? I understand that the glycol is in there to prevent the actual freezing. What are the other components for in a coolant?

Shelly Eckert (05:09):

Let's talk about fully formulated. Fully formulated, you typically have a lot of nitrites and molybdate in the coolant. What that does is it creates a blanket on the cooling system. You go to an extended life coolant, that blanket gets removed and the organic acids are floating around. And when cavitation starts, it goes in and stops the cavitation. But by doing that, it improves heat transfer properties by 10 to 12%

Bryan Furnace (05:35):

Because of the fact that you don't have that insulating blanket on the inside of all of your coolants.

Shelly Eckert (05:40):

That's correct.

Bryan Furnace (05:40):

Or cooling system.

Shelly Eckert (05:41):

Cooling system. Mm-hmm.

Bryan Furnace (05:43):


Shelly Eckert (05:44):

It's interesting technology. I think it was an accident how it got developed, but that's a lot of how science is done.

Bryan Furnace (05:51):

Yeah. Interesting.

Shelly Eckert (05:53):

Mm-hmm. It was first tested in New York City taxicabs.

Bryan Furnace (05:59):


Shelly Eckert (05:59):

Yep. And then what happened was they realized that their water pump failures were gone, and that was the birth of deck school.

Bryan Furnace (06:07):

Interesting. Now moving forward, our big test that we constantly are told about is checking for glycol levels. We've covered that. Now I've also heard you talk about doing pH testing. What is the, go ahead. You look like there's another point you want to add.

Shelly Eckert (06:24):

You're getting my signals. Yep. If the freeze point is off, there are charts that you can use to adjust. What it has is various sump sizes, and then you just match up what your freeze point is off the refractometer to the sump size, and it tells you how much to drain out and whether that is, if you've got too much water, you've got one chart. If you've got too much glycol, you've got a different chart. If you have to adjust with water, you do that, but you won't use a deionized or bottled water. Deionized distilled bottle comes last, not tap water, not out of a hose. Do I know that that happens? Yes. That's why the descaler is added into the coolant. But I tell my guys, no adjusting of the coolant until you test the pH. These two tests go hand in hand because if the pH is bad, you're going to drain that coolant out anyway. Why spend the time adjusting the coolant? Because if you try to levelize that coolant back to the mixture that you want to use, that does not change this at all.

Bryan Furnace (07:31):

Yeah. What is pH telling us?

Shelly Eckert (07:36):

For an extended life coolant, you're focused on getting an eight on a quality extended life coolant. If you're dealing with a fully formulated or conventional coolant, then you're looking typically at a 10 or 11. And sometimes when a coolant is advertised as being a long life, that's not necessarily an extended life coolant. And that could come across as being our 10 or 11. But if you know you're on extended life coolant and all of a sudden it shows that you're a 10 or 11, you are getting too much nitrites from somewhere. That could be coming from somebody pouring in liquid supplemental coolant additives, SCAs or DCAs, a pre-charged filter's installed. Or better yet, a pre-charged filters installed and somebody on top of that added more SCAs at the time that they changed the filter. Just adding way too much in at one time. The other way that it can happen is that conventional or fully formulated coolant was added into the extended life coolant.


It gives you an idea that something's going on and you got to figure out where is it coming from, and then just remedy it, because a lot of the OEMs have removed these filters just to prevent this from happening.

Bryan Furnace (08:52):

I guess, what's the downside of the pH being off? What's that going to do to my coolant system if the pH is not where it's supposed to be?

Shelly Eckert (10:53):

Well, it depends on the OEM. Sometimes, and it depends on the aluminum being used for the radiators, for example. Sometimes the nitrides will react more with some types of aluminum versus others. When they do react, can cause ammonia hydroxide and then that can eat the seals and cause head gasket leaks.

Bryan Furnace (11:14):

Okay. You're talking over time, this could be a major problem.

Shelly Eckert (11:19):

Mm-hmm. The cooling system should be utilized to help understand what the equipment is doing, what's happening. It's used as a diagnostics tool, in essence.

Bryan Furnace (11:31):


Shelly Eckert (11:32):

It should be part of the technician's toolbox. If, for example, the pH is seven or below, that's a clear indication that either you have a head gasket leak getting into the cooling system or an EGR leak getting into the cooling system. And the only way to fix that is drain it out.

Bryan Furnace (11:49):

That was going to be my next question. If I don't know what kind of coolant I've actually got in the coolant tank, whether it was someone else that did the last coolant swap or it's a new piece of equipment we just acquired, really it sounds like the only way to kind of zero everything out is do a full system flush, fill it with a known, keep notes of what you're putting in there so that going forward you have all of this information so you can start using this as a diagnostic tool.

Shelly Eckert (12:17):

I'm a big proponent of that. Because if you don't know, if you start mixing two different coolant types together, the additives can fight each other, and they can fall out. The analogy is my best analogy, because I think everybody has probably done this. When you gargle with salt water and you pour too much salt into a warm glass of water and it starts to pile up at the bottom of the glass, that's what we call flocculant or white flocculant, that falls out. That's just too much. And then you've lost the protection of your cooling system for an added perspective.

Bryan Furnace (12:49):

And I'm assuming you're also gumming things up because now you have solids in a system that's supposed to be completely liquids.

Shelly Eckert (12:56):

Mm-hmm. You can plug things up. And again, 40% of the engine related failures are due to coolant.

Bryan Furnace (13:03):

I never would've guessed that.

Shelly Eckert (13:05):

It's crazy, isn't it?

Bryan Furnace (13:06):

That is crazy.

Shelly Eckert (13:08):

Well, it's misunderstood and a lot of times we are focused on seasonal maintenance, but it really shouldn't be. That piece of equipment where you're going to be changing the oil, test the coolant.

Bryan Furnace (13:21):

Yeah. When you do these pH, you're just getting pH strips and dipping it into a sample of coolant. Is there anything more sophisticated than that?

Shelly Eckert (13:30):

No. You take it as a scale of zero to 14, just like any other pH scale, even like what you use to test pool water, right?

Bryan Furnace (13:38):

It's like testing pool chemicals. Yeah.

Shelly Eckert (13:40):

Exactly. And then you just match it up to the colors. Now I realize that colorblindness is out there, so if you're not sure which color, ask somebody else to look at it.

Bryan Furnace (13:52):

Ask a friend.

Shelly Eckert (13:53):

Ask a friend.

Bryan Furnace (13:54):

Phone a friend.

Shelly Eckert (13:54):

Phone a friend, right? That's right. And here's the other thing. This is dye receptive. If they sit too long, it can actually make that pH test strip look darker than it actually is.

Bryan Furnace (14:12):

Sure. Just because it's absorbing the dye of whatever is in the coolant?

Shelly Eckert (14:16):

Yes. It's basically still reacting.

Bryan Furnace (14:18):

My final question is, how often do I need to be doing these tests? Is this a once a year deal? Is this a couple times a year? Is it when the seasons change?

Shelly Eckert (14:27):

It takes nothing to do these two tests. No time at all. If you had the piece of equipment in for an oil change, just add this to the PM worksheet. Just check it, right? That's what I would recommend. Versus if you're not sure about what's going on, if you're not sure between the refractometer and the pH test strip, that takes you three seconds, maybe four to do.

Bryan Furnace (14:55):


Shelly Eckert (14:56):

Then you're going to draw a sample and send it into a commercial lab. But by the time you have transit and the testing time, getting the report back, you're talking about week and that piece of equipment is back out on the job.

Bryan Furnace (15:10):

Yeah. Would you recommend on top of these tests that I'm able to do in my shop super quick, knock it out of the park, do I need to send coolant samples off to a lab like I do oil samples, transmission samples, all of that? Or can I mostly get by doing these tests myself?

Shelly Eckert (15:28):

When I first came on board, I knew at the lab level, well back 10 years ago, 11 years ago, about 10% of the sample population that comes through the commercial labs are coolant samples. Does that put into perspective?

Bryan Furnace (15:43):


Shelly Eckert (15:45):

That's when I was asking for a coolant maintenance kit, something we could use to train our customers and train how to use this and how to monitor the coolant. Because it was fine in the past of saying, hey, maybe check the freeze point twice a year. That all changed when EGRs came into play. It just needed to change. And technology has changed. If it's something we can do out in the field and we can fix it right then and there, rock on.

Bryan Furnace (16:12):

You would recommend really doing glycol checks a couple times a year, maybe when the season has change, but pH tests you'd recommend doing regularly through the year just because you could diagnose an EGR problem before there's any other indicator that something's going on?

Shelly Eckert (16:28):

Yeah. That or coolant has been mixed because one thing that we have not spoken about and should have mentioned it, for clarity of that coolant, you want to make sure it's not hazy, not cloudy, and it doesn't have any sediment it, right?

Bryan Furnace (16:43):


Shelly Eckert (16:43):

The overflow tank, it might look, let's say red on the outside, but a lot of times the dye leaches into the sump, the overflow tank. The best thing is to suck some of that coolant out. This is a pipette, it's small. If you want to do a faster job, go get a turkey baster from Walmart, or just go out to Amazon and order your refractometer or turkey baster and your pH test strips.

Bryan Furnace (17:12):

There you go. Full coolant kit, 12 bucks.

Shelly Eckert (17:15):

Full coolant kit, right? I usually will use something to suck out the coolant and I'll put it in something that is fairly clear, which you can get bottles or these are little tiny plastic beakers, but you can get clear bottles at Walmart or one of the arts and crafts stores like Hobby Lobby or Michael's Arts and Crafts, right? Then just look at it and make sure there's nothing in it because if it's cloudy, then you probably have those additives fighting.

Bryan Furnace (17:50):

Gotcha. And in that case, you need to do a full system flush.

Shelly Eckert (17:55):

I would recommend that, yes.

Bryan Furnace (17:57):


Shelly Eckert (17:57):

Mm-hmm. And start over. There is another test strip that's on the market that is an organic acid test strip. You really need to know which extended life coolant you are on because these are going to be coolant specific.

Bryan Furnace (18:13):

Yeah. If you don't know, there's no point in doing that test. You're not going to glean any information from it.

Shelly Eckert (18:18):

No, because you could get a false positive or false negative.

Bryan Furnace (18:23):


Shelly Eckert (18:24):

Right. There's also nitrite test strips on the market. There's also test strips that have multiple tests in one test strip, freeze point, nitrite. I think I've even seen molybdate that you can use also in the field, but they're very common for test strips and\ you can probably get them at Napa and Carquest, Caterpillar dealers, John Deere dealers. They're going to be all over the place.

Bryan Furnace (18:50):

Well, Shelly, thank you for all of the information. This has been helpful. I continue to learn more and more about a system that largely gets ignored, and I didn't realize you could really diagnose things like EGR problems or exhaust leaks through coolant. That's pretty fascinating.

Shelly Eckert (19:06):

Well, it's all interrelated, right? It's much easier to do that versus relying on the lab because stuff happens. Stuff happens, and if you can catch it in the field, in the shops, you want to be able to do it and it's cheap, so why not?

Bryan Furnace (19:23):

Yeah, absolutely. Well, thanks again and we'll talk to you here soon.

Shelly Eckert (19:27):

All right, sounds great. Thanks, Brian.

Bryan Furnace (19:29):

Well, thank you again to Shelly for coming on the show and sharing her expertise about coolants and giving us an idea of why we're running these tests and what they're telling us about our coolant systems. As always, I hope this helps you in your business. We'll catch you on the next episode of The Dirt.