Don’t lose your cool By Lane Lindstrom

Even if you’re the lead vehicle on a ride, your own rig can kick up enough dust to drift into and settle on the radiator fins and impede air flow through the radiator.

Even if your side-by-side has never overheated, you most likely know someone whose UTV has. It’s not fun, especially when you’re far away from your truck and trailer.

While an overheated vehicle is not fun, the situation is usually preventable with a few simple preventative maintenance steps.

Overheating, as Jerry Matthews, part owner of Starting Line Products ( pointed out, is one of the most common issues UTV owners fight with while off-roading. He said, “This typically results in severe frustration, as it usually ends up leaving them far behind the rest of their group as they struggle to keep their vehicle cool.”

And, he said, it usually all boils (pun intended) down to some fairly simple causes. “In almost every instance we have found these overheating issues are due to dust or mud build-up on the fins of the radiator from previous rides, low coolant and/or accessories that impede airflow,” he said.

Radiator fins: Ideally, this is what your radiator fins should look like prior to your ride, but not necessarily after a ride, especially depending on the type of riding you did. Dunes might leave them this clean but not dirt or mud. Clean radiator fins equals fewer (if any) overheating issues.


“Even though the radiator fins may look clean, have been recently blown out with compressed air or even washed out with water, there may still be enough dust and dirt on them (usually between the fins) to keep the radiator from effectively transferring heat efficiently,” Matthews said. A radiator is essentially a heat exchanger. Its function is to cool the engine by “exchanging” the engine heat that has been transferred to the coolant with the cooler air that is pushing across and through it either naturally as the UTV moves along the trail or via an electric fan that pulls the air through it.

Using a low-pressure garden hose is a safe bet to clean out your radiator fins. Don’t use a high-pressure car-wash wand or other high-pressure power-washing equipment, which can damage the fins by distorting or bending them.

The fins are heat sinks. They substantially increase the surface area that the heat from the coolant inside of the radiator is exposed to. This makes the radiator more efficient as it can conduct more heat from the coolant inside to the air outside.

More specifically, consider how the insulation in your house keeps the summer heat and winter cold from penetrating the walls and entering your house. Dust on your radiator fins keeps the engine heat that has been transferred into your coolant from transferring through the radiator. Even though the radiator has air passing through its fins, dust insulates the fins, making them less effective at transferring the heat out of the radiator and into the atmosphere.

SLP’s Jerry Matthews suggests using a diluted solution of Simple Green to help loosen dust and dirt from between the radiator fins. Let the solution soak in for about 10 minutes before rinsing off.


Most modern side-by-side (and ATV) radiators are made from aluminum. Aluminum is the metal of choice because it is a good conductor, is lightweight, relatively inexpensive and fairly durable. “Copper or brass used to be the material of choice for radiators, but due to its cost and weight, copper radiators have all but gone away,” Matthews said.

Of course, not all particles clinging (or trying to cling) to your radiator fins are created equal. Potential hazards are dust, mud, sticks, leaves and just about any other debris you might encounter. There is a chance that your favorite dunes, mountain trails, desert trails, mud hole or even rock-crawling sections have quantities of these potential hazards.

Let’s start with sand. “Sand is normally coarse and doesn’t have too much dust associated with it,” Matthews said. “I typically consider riding the sand dunes a fairly ‘clean’ environment. Typically, very little cleaning has to be done when running on the sand. But, all sands are different, so customers will need to beware of the sand they are riding in.” While sand may not compromise the radiator-fin surfaces, it does put an enormous amount of heat into the coolant. Sand puts a big load on the engine, and rpm levels are typically high.

Bigger problems can arise from small branches and leaves you encounter when riding on tree- and shrub-shrouded trails. Pay particular attention to what whacks up against the front of your vehicle. And, that includes any tree branches lying on the trail. Small branches are typically kept out of the radiator by the grill. “I’d be more worried about small branches damaging the fins than plugging the radiator,” Matthews said. “Leaves would typically be caught by the grill, but leaves can be dangerous. They tend to stick onto the radiator or grill until the airflow stops. They can totally block all airflow resulting in an overheating issue, but riders would typically know this is happening based on the foliage they just rode through.”

If you have foliage trapped in the grill or radiator, simply stop and remove it at the first safe spot to do so.

Mud (and muddy water) might just be enemy number one for a side-by-side’s (or ATV’s) radiator and can result in plugged fins and then overheating. It doesn’t mean you have to avoid your favorite mud hole; you just need to pay attention to see if your rig is overheating, and then act on it if that does happen.


Not surprising, mud is probably the worst enemy of your radiator. It totally plugs the radiator fins, blocking and insulating them from doing their job. Like riding in the mud or even just muddy water? Then Matthews suggests you should clean your radiator as soon as possible. If you let it sit and dry, it can take a lot of work to remove it, as the dried mud that is in the interior of the radiator fins has to get wet prior to it washing out.

“Sometimes you can blow it out with compressed air (depending on the mud and at the risk of fin damage), but normally the best way to do it without radiator-fin damage is to wash it out,” he suggests. “Since the radiator is hot when running the machine, it usually doesn’t take too much time for the mud to dry. I know customers who carry a suction tube with them that they use to wash out their radiator when they run a lot of mud. As soon as they get to an area with clear water, they suck some up and spray it through their radiator. This suction tube is like a Super Soaker used in water sports; it’s like a large squirt gun.”

But, most rides on mountain trails, in the desert or other off-trail riding locations require you do a little post-ride work.

Or, if you see your temperature topping out quicker and higher than normal, it is time to clean your radiator fins. Monitoring your temperature gauge, no matter where you ride, is your very best indicator of when service is needed.


“We recommend cleaning your radiator by spraying into the fins from the front side with a squirt bottle filled with a diluted solution of Simple Green,” Matthews explained. “This solution loosens the dust and dirt that is between the fins, and should be applied when the radiator is cool.”

Once the solution of Simple Green is applied, let it sit for approximately 10 minutes to let it work on dislodging the dust and dirt particles. Then rinse out the radiator by running water from a garden hose through it from the front side. 

Matthews cautioned, “We do not recommend using a high-pressure car-wash wand or other high-pressure apparatus, as the high pressure can bend and distort the radiator fins, making them less effective.” Use a low-pressure garden hose to simply rinse it out. Verify your progress by watching how much dirt and debris comes out the back side of the radiator. 

“You will be surprised, as usually they don’t look that dirty until you rinse them,” Matthews said. “The amount of dirt and debris trapped inside the fins is amazing. Usually only one treatment is necessary, but for extremely dirty radiators, you may need to repeat the process several times until the rinse comes out clean.”

While sand is more coarse than dirt and dust and doesn’t cling to radiator fins like those do, it doesn’t mean you shouldn’t inspect and, if necessary, clean your radiator after sandy rides.


Prior to each ride, check the coolant level to ensure that you have not lost any coolant from an overheating episode. Top it off as needed. Always do this with a cool radiator, as hot coolant that is under pressure can be very dangerous.

Matthews also suggests, “It is wise to make it a habit to monitor your coolant temperatures, especially on hot days. When you stop, do not shut off your UTV immediately; instead, let it idle and monitor the coolant temperature. If the coolant temperature is above 195 degrees Fahrenheit, let it idle until it comes down below this temperature.”

When you first stop, it is normal for your vehicle to heat up as it idles, and then once the fan kicks on, it will cool back down. Let it go through this cycle so that the temperature of the entire cooling system is below 195 degrees Fahrenheit and dropping. “Doing this helps keep your precious coolant inside the radiator and cooling system rather than spewing some out onto the ground,” he said.

You probably don’t need it spelled out what the result would be if you choose to ignore overheating issues on your vehicle. But, just in case you’re curious, Matthews explained that most engines will go into limp mode, reducing available power. “Then if you continue and the overheating continues, the pressure will build until it pops the radiator cap (most are set at 15 psi) and purges some coolant out of the radiator into the overheat reservoir,” he said. “If you continue, the overheat reservoir will eventually overfill and coolant will puke out onto the ground or leave the bottle in the form of steam, leaving the cooling system low on coolant.” That results in a quicker overheat the next time if the coolant is not topped off.


“The cooling system is a closed system, and as long as you don’t severely overheat it, it will not require maintenance,” Matthews pointed out. “However, if you severely overheat it, you will need to top it off prior to the next ride. Now, if you overheat the system and continue on your merry way, engine damage will eventually occur as the cooling system is compromised and the engine has no way to remove the heat caused by the combustion process. This can cost thousands of dollars on a UTV.”

In modern side-by-sides, the engine fan is an important component of the cooling system and should be checked periodically. Normally, the fan will kick on somewhere between 180 and 200 degrees Fahrenheit, and you will hear it when it comes on. “If you never hear your fan come on and your temperature is running around 200 degrees, you should check it to make sure it is in working order,” Matthews said. “Normally, I find the simple things to be the problem, such as a blown fuse, mud, dirt or a stick lodged in the fan blade.” But, sometimes the fan can go bad or the wiring could get cut or damaged.

Here’s another tip from Matthews. Beware when choosing accessories that can block or disturb airflow to the radiator. “Ask yourself prior to purchasing or installing items, such as grill guards, lights, winches and bumpers if they will impede airflow to the radiator,” he advised. “Choose models and mounting locations that will not affect airflow.”

Face it, we run our UTVs in some pretty dusty/dirty conditions. Even if you are running alone or leading the group, your car is exposed to dust and dirt kicked up by oncoming traffic, as well as your own vehicle. The radiator takes this in and blows most of it through, but some collects on the fins, insulating them from the cool air passing by.

“As well as monitoring your coolant level and temperature, do your UTV a favor and periodically clean the radiator fins,” Matthews said. “You will be surprised at how much cooler it runs.”

Aftermarket accessories look sweet on a side-by-side and are useful in many different riding situations. However, depending on the number of accessories and where they are mounted, they can hinder air flowing over the radiator fins.


If you exhaust this list and your machine is still running hot, further checks are needed. Make sure the coolant is actually circulating. You may need to make further modifications like rear-mounting the radiator. That is common in racing where other cars are constantly roosting the front of the car. Also explore options like a more efficient impeller and housing. Boyesen has been rolling out models for UTVs. They make a huge difference on quads and should do the same for UTVs. Most UTVs are designed pretty well, so if there is chronic overheating, get a tech to track down the problem or problems.

If you experience overheating or just high-running temperatures, you may be able to flash the ECU to change when the fan kicks on and make it run longer.

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