Understand why your Lexus NX 300 sometimes overheats in stop-and-go traffic. Diagnosing common cooling system problems early will help prevent potentially costly engine damage and repairs.
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At M & R Automotive, near Palo Alto, CA, we often diagnose cooling system problems with the Lexus NX 300. Many owners notice the engine running at a perfectly safe operating temperature on the highway only to see the gauge start to rise in traffic jams. In heavy, stop-and-go traffic, some Lexus NX 300s with cooling system problems can overheat, causing potentially severe engine damage.
Many times, a Lexus NX 300 overheating in traffic is due to a failed radiator cooling fan. When you’re driving at highway speeds, air naturally flows through the radiator, which naturally removes heat from the coolant circulating between the engine and the radiator.
When you slow down or get stuck in stop-and-go traffic, the electric cooling fans are supposed to activate to pull air across the radiator. If one of the fan motors fails or an electrical relay stops working, there won’t be sufficient airflow passing over the radiator. This allows the engine temperature to rise quickly while the vehicle sits still.
A stuck thermostat is another common cause of overheating in the Lexus NX 300. Normally, your car’s thermostat remains closed while the engine warms up, then opens once normal operating temperature has been reached. If it becomes stuck in the closed position, hot coolant remains trapped inside the engine instead of flowing through the radiator. Without proper coolant circulation, the engine temperature continues to rise even though the cooling system appears to have enough coolant in the reservoir.
Of course, low coolant levels are also another potential cause of overheating in a Lexus. Normally, the coolant absorbs engine heat as it cycles through the engine block. It then carries it to the radiator where the outside air draws out the thermal energy. Even a minor leak from a tiny hole in the radiator, hoses, or a bad water pump will gradually reduce the coolant volume.
At first this will impede the engine’s ability to cool properly at slow speeds. Left unchecked, the coolant levels can become so low that air enters the system, and the coolant can no longer circulate properly.
A clogged or damaged radiator could also cause overheating issues in slow traffic. Debris, rust, and particulate matter that contaminate the coolant can become trapped in the radiator fins. This reduces the cooling system’s ability to release heat into the environment.
Arguably the most serious potential cause of overheating issues is a bad water pump. It’s essentially the beating heart of the cooling system as it circulates coolant throughout the engine and radiator. As a car’s water pump ages, things like damaged bearings, a worn impeller, or even something as simple as a slipping drive belt may reduce coolant circulation. Early signs of a problem like this usually start out with overheating in traffic and will get worse rapidly.
In all these cases, early diagnosis is key for catching a minor problem before it leads to severe overheating damage.
If your Lexus NX 300 has been running hot in traffic, contact M & R Automotive today. Our technicians will perform a complete cooling system inspection to diagnose the problem and come up with the most cost-effective repair plan.