Why Does This Kia Sorento Keep Overheating?

"It’s a Kia."

Photo by: adamszaira & Mark Bishop

By: Chad Swiatecki

Sep 8, 2025 at 9:00pm ET

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Despite everything looking normal under the hood, one woman’s Kia Sorento couldn’t keep its cool. What followed was a viral crowdsourced repair job, one thermostat theory at a time.

The short viral clip from Kia Sorento owner Zaira (@adamszaira) shows the hood open on the 2011 vehicle, with her desperately asking for ideas as to the possible cause of repeated episodes of overheating.

Crowdsourced Diagnostics

It didn’t take long for the comments section on the clip to turn into a virtual repair shop. Viewers chimed in from all sides with a flurry of DIY diagnoses, many starting with a single suspect: the thermostat.

“Thermostat always get stuck, just change it,” one insisted. Another pointed out the telltale signs of a failed head gasket, advising her to open the radiator cap while the engine was running and look for bubbles that could be a potential indicator of combustion gases leaking into the cooling system. That kind of diagnosis, though, might be a bit ambitious for a smartphone in selfie mode.

Still, the most frequent suggestion is as simple as it is affordable: swap the thermostat. “It’s probably a blown head gasket or a thermostat,” one viewer wrote, hedging their bets. “Three most common would be thermostat stuck closed, fans not cutting on, or air in the coolant system,” another said, offering a broader mechanical checklist.

And while some replies leaned more toward jokes (“Check the blinker fluid,” “It’s a Kia,” “Buy a new car”), the sheer volume of legitimate responses underscored something bigger: automotive TikTok has become a real-time crowdsourcing tool for drivers trying to figure out car trouble without the stress or cost of a shop visit.

In a follow-up comment, Zaira confirmed the outcome: “It was the thermostat!” she wrote, laughing at the fact that dozens of commenters nailed it.

A thermostat may be a small part, but it plays a critical role in engine temperature regulation. When functioning correctly, it stays closed to help the engine warm up and then opens to allow coolant to flow through the radiator and keep the engine from overheating. But if the thermostat sticks shut—as appears to have been the case with Zaira’s Sorento—coolant can’t circulate properly, causing the temperature to rise rapidly and potentially leading to major engine damage.

Stuck thermostats are a common cause of overheating, especially in older vehicles. According to YourMechanic, signs of thermostat failure include temperature spikes, strange noises, or leaking coolant. In most cases, the fix is relatively straightforward and costs between $150 and $500 at a shop, or even less for DIYers. Parts alone often run under $30 at retailers like AutoZone or NAPA.

Cooling System 101

While Zaira’s issue turned out to be a classic case of thermostat failure, her situation became a learning moment for other drivers. Overheating issues in vehicles, especially older ones like her 2011 Sorento, can stem from several sources. Experts recommend a step-by-step diagnostic approach when the temperature gauge starts climbing.

First, check the coolant level, not just in the overflow reservoir but directly in the radiator once the engine is cool. Low coolant could point to a leak, faulty water pump, or even a failing radiator cap. Next, ensure the cooling fans are operating. When a fan motor, relay, or temperature sensor fails, the engine can overheat in traffic or while idling.

Air trapped in the cooling system, especially after a coolant flush or radiator service, can also cause temperature spikes. That’s why proper “burping” of the system is important. Guides show how to safely remove air pockets and ensure coolant circulates correctly.

How To Bleed A Cooling System

In worst-case scenarios, a blown head gasket may be to blame. That can lead to coolant mixing with oil or combustion gases entering the cooling system, both of which are costly repairs. Telltale signs include white smoke from the exhaust, milky oil on the dipstick, and constant overheating despite a full coolant tank. Tools like K-Seal’s Combustion Leak Detector can help detect a blown head gasket at home.

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For Kia owners specifically, factory powertrain warranties may offer relief—especially for vehicles under 10 years or 100,000 miles. According to Kia’s warranty guide, certain repairs may be covered depending on age, mileage, and dealer diagnosis. Several commenters pointed this out to Zaira, encouraging her to explore warranty coverage just in case the fix wasn’t as simple as a stuck thermostat.

Motor1 reached out to Zaira via direct message. We’ll update this article if she responds.