No one likes to be unexpectedly surprised by an overheating car. You’re in traffic, waiting at an intersection for the light to change. The driver in the vehicle next to you is blasting music loudly and you’re anxious to be on your way. Just before the light turns green, you notice the temperature gauge is rising, dialing right toward the red line. But, once on the move, the temperature begins to drop to a normal running position. Then, at the next light it happens again. That’s when you wonder aloud, “Why does the car temperature gauge get hot while idling?” Unfortunately, like many car problems, the answer isn’t necessarily straightforward.
Why does the Car Temperature Gauge get Hot when Idling?
The way your car is cooled depends on several components. Because an internal combustion engine creates so much heat, the engine would melt if not effectively cooled. Cooling components include: the water pump, radiator, thermostat, hoses, and coolant. Each is necessary to keep a vehicle’s engine from overheating during normal operation.
“The water pump pulley is a vital part of a vehicle’s engine cooling assembly. This pulley enables the water pump belt to drive the pump. The pump, in turn, sends liquid (coolant or water) throughout the engine system, allowing the quick dissipation of engine heat. When the pulley breaks, this whole process is disrupted. This naturally leads to cooling system malfunction and engine overheating.” –Auto Parts Warehouse (http://www.autopartswarehouse.com/water_pump_pulley~pop.html?redirect=1)
Of course, there are other factors which contribute to how hot an engine gets, which include, but are not limited to: the speed at which you drive, the length of the drive, the weather and road conditions, and more. Even the age of your car and its driving history are factors in how it operates and can contribute to the temperature gauge getting hot when idling.
One common scenario for a temperature gauge to go into the red which might be the culprit is the lack of air moving through the radiator (even though coolant is still circulating through the system). If you rev the engine while idle, more coolant is circulated, which will temporarily cause the gauge to fall. This and other scenarios can be due to one or more of the following reasons:
- A broken hose. Over time, hoses start to fail and eventually break. Just a small leak in a hose can be enough to cause insufficient coolant to circulate through the system and result in overheating during idle or normal operation.
- A failing water pump. If you hear a screech coming from under the hood, you are likely to see coolant leaking onto the ground under the front of your car. This is a sign of a failing water pump, something which needs to be replaced right away.
- Failing or broken fan belt. The water pump is driven with a belt using the car’s engine. If the belt becomes loose, begins to fail, or breaks, the water pump will not properly operate, causing overheating to occur.
- Faulty or missing radiator cap. Without a reliable radiator cap, necessary pressure is not maintained and the system becomes unstable as a result.
- One or more bad head gaskets. When head gaskets fail, large plumes of smoke will flow out of the exhaust. In addition, a bad gasket can lead to a misdirection of coolant into a cylinder.
To know what’s truly going on with your vehicle, take it to an experienced mechanic immediately to avoid serious damage and costly repairs. A car temperature gauge which gets hot when idling is a significant problem and needs prompt attention.
Until next time, be safe out there!