With temps falling, it's time for a coolant checkup

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Updated Nov 28, 2022

Temperatures across the U.S. are tumbling, and the temperature swing can be a lot for a truck's components to handle, especially the coolant system. 

For most of at least the last six months, the coolant's ability to keep operating temperatures in line has been its primary function but soon – if not already – its ability to withstand subfreezing temps will be front and center.

Chevron Lubricants Commercial Fleets Business Consultant Shelly Eckert, who joins Jason and Matt on this week's 10-44, said while a good maintenance program isn't necessarily tied to the changing of the seasons, there's no time like the present to give your coolant system a thorough checkup. 

Contents of this episode

00:00 Coolant maintenance

01:57 Refractometers

02:56 pH test strips

06:34 Pressure checking the radiator cap

07:01 Colors of coolant


This week's 10-44 is brought to you by Chevron Delo 600 ADF ultra-low ash diesel engine oil. It's time to kick some ash.

Temperatures are dropping faster than spot market rates. Are your trucks ready for the changing of the seasons?

Jason Cannon
Hey everybody, happy Black Friday and welcome back to the 10-44 a weekly webisode from the editors here at CCJ. I'm Jason Cannon and my co-host on the other side is Matt Cole. It's a misnomer that there's a seasonal component to maintenance. A good fundamental PM program is a year round thing, but as the seasons change, the demand on a truck system and its components also changes making at least a seasonal checkup a good idea.

Matt Cole
In Alabama, where Jason and I live, low temps hit the upper twenties late last week. Just a few weeks before, highs were in the eighties. That kind of sudden temperature swing can really bring into focus the performance of your coolant.

Jason Cannon
But there's a lot more that goes into a coolant check than just making sure that there's some in the reservoir. And Chevron Lubricants commercial fleet business consultant, Shelly Eckert joins us this week to share some tips on how fleets can make sure that their trucks are up for winter's challenge.

Shelly Eckert
The way that we approach coolant maintenance, or I approach coolant maintenance, is really to encourage year round coolant maintenance, including it into your normal PM process. We work with our fleets to make sure that there's a section on their PM worksheets that includes bullet points to inspect their cooling system, such as making sure you're checking your freeze point to make sure it is adequate and that you're not out of balance with the amount of water to glycol to start with because that is the number one critical physical property of the coolant. The way to properly check that is to utilize a refractometer.

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Matt Cole
There are more than a handful of ways to test a coolant, but Shelly is adamant that fleets lean most heavily on two, a properly calibrated refractometer and test strips.

Shelly Eckert
I've seen things out there that are like the floating balls and those don't work, so I make my guys throw them out because the second they suck up any oil when they've test testing that, it causes the floating balls to be off. So therefore, the freeze points will be off. I will go into a shop and I'll ask them where all the refractometers are and bring them to me and I'll ask them, "Has this been calibrated?" Some will say yes and some will say no. And I'll ask them, "How do you check to make sure this is reading correctly?" And I get some very crazy answers and I'll tell them it's room temperature water because all water freezes at 32 degrees. So it's easy, right? You can use the water from the sink or even water from the streams. It's just a little water. And make sure that it's just a room temperature water, put it on the refractometer and you make sure that it's calibrated correctly.

Matt Cole
Now, about those test strips.

Shelly Eckert
One of the things you first want to do is when you look at a coolant, you want to make sure it's clear, it's bright and it's free of any particles. Okay? And then the next step would be the refractometer. I encourage always to test with a pH test strip because you can determine a lot of things with the pH test strip such as if your coolant is... Typically, an extended life coolant is going to be about an eight or nine per pH. There are pH test strips widely available, but you want to have something that's resistant to the dye of the coolant because the dye of the coolant can also interfere with the test strips. Using the pH test strip, which is the same scale whether you're testing your pool water, it goes from zero to 14. And as I've shared before, the pH on a coolant should be an eight or a nine. When it drops down and that coolant becomes acidic, you have to look for the source of why it's become acidic.

If it increases, it typically indicates that if you're running at a nitrite-free coolant, it'll indicate that you have nitrites in your cooling system. So it's a nice little trick to monitor your cooling system easily in the field. We've also, and this is where it gets a little complicated, we have these carboxylate test strips, organic acid test strips, right? That's going to be very formula specific. So you have to be careful with that one. You know what coolant you have in the cooling system and honestly, when it comes to over the road fleets, the only time that we have an opportunity to make sure that the truck has the proper amount of coolant and the proper physical properties of the coolant is when that truck is in the bay. Because as soon as it leaves and the driver has it, if they have to top up with coolant over the road, you could be commingling two different coolants. That's allowed up to 25%, but once you get to 25%, you get those dyes mixing, you can't really tell, which is why you have to really test your coolant to make sure everything's good to go.

Jason Cannon
Where coolant maintenance can go totally off the rail, Shelly said, is when the people in charge of buying coolant decide to make a change and don't tell the people in charge of maintaining it, a switch from a conventional coolant to an extended life coolant where certain additives and filters may no longer be necessary, for example. There's also an often overlooked element of coolant testing that can be a critical component to the entire system. Shelly tells us about that after a word from 10-44 sponsor Chevron lubricants.

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Shelly Eckert
Make sure that you are also pressure checking the radiator cap because those can be inexpensive and they can break. If the system's not properly pressurized, you can create the water to boil off and then you create more glycol and sometimes that's not so good. You'll lose your heat transfer properties because it can boomerang and then it can go up into the EGR, cause the EGR to crack and cause gas from the EGR to get into the coolant and make the cooling acidic

Matt Cole
Coolant is pretty universally referred to by color. You either use the green or the pink. But the color isn't part of the protection and Shelly said you need to understand what's in the system, so when you're topping off, you're using the same product.

Shelly Eckert
There is a rainbow of colors out there. TMC put an RP out after the colors were out of a rainbow as a guidance of what was to be determined for color, meaning an extended life coolant should be... Nitrite extended life coolant should be red. At one time, they had the nitrate free coolant being identified as yellow. For on highway, it changed when Detroit Diesel wanted a red or an orange color coolant to identify as a nitrite-free coolant. So you have all kinds of colors out there. One of the things you have to understand is the fine print of the coolant. I had a situation, there's a coolant on the market that says it's a million mile coolant, but when you look at the fine print, it says you have to readditize every 150,000 miles. That's not an extended life coolant. It's a long life coolant. Then you have some coolants out there that are... There's a fluorescent green coolant that is a Japanese hybrid coolant and it's green. So you have to understand what is in your cooling system and should maintain that with the same coolant type.

If you are a fleet that is on a red coolant, and a lot of times, these trucks, they're going to be labeled with what coolant is in that sump and if it's not labeled, once you put what you know you are using, label it of what is in that cooling system because the shop knows what they're using, but the driver may or may not. I've seen for extended life coolants out there, blue and red and pink and yellow. You have to just be careful because there's circumstances where marketing addresses it as being a universal coolant. Well, that may be for automotive, but not for heavy duty. So you have to know what your coolant is because honestly, 40% of the engine related failures are coolant related. So coolant is a very important piece, which is why we put the Cool Tools together to get the technicians an added kit into their toolbox.

Jason Cannon
That's it for this week's 10-44. You can read more on CCJDigital.com and as always, you can find the 10-44 each week on CCJ's YouTube channel. If you've got questions, comments, criticisms, or feedback, please hit us up at [email protected] or give us a call at (404) 491-1380. Until next week, everybody stays safe.