Can the car still be driven if the thermostat is faulty?
3 Answers
If the thermostat is broken, the car should not be driven. The thermostat is a device that controls the coolant circulation. If it fails to open, it can easily cause the engine temperature to rise excessively, increasing the risk of spontaneous combustion in hot conditions. If it fails to close, the engine's water temperature will be lower than normal, leading to poor lubrication, increased fuel consumption, and accelerated wear. Symptoms of a faulty thermostat include: 1. The water temperature reaches the normal value during idling or low-speed driving, but drops significantly when the speed exceeds 50, preventing the engine from reaching the normal operating temperature. This results in loud engine noise, poor acceleration, and increased fuel consumption. 2. If the thermostat fails to open, the water temperature will remain in the high-temperature zone, and the radiator fan will not turn on, which can easily cause the engine to overheat and reduce its lifespan. Additionally, during winter warm-up, the water temperature rises slowly, and the idle speed remains high, taking at least 10-20 minutes to reach the normal temperature.
With over twenty years of driving experience, I genuinely don't recommend pushing through when the thermostat fails. The thermostat controls engine temperature regulation. If it gets stuck in the closed position, coolant won't circulate, and the engine temperature can skyrocket like a rocket, triggering overheating warnings or even smoking within minutes. I once had the temperature gauge spike red mid-drive and had to pull over immediately—otherwise, the engine could have burned out pistons or head gaskets, leading to repair costs in the thousands. Even if it's stuck open, the engine warms up too slowly, feeling sluggish while driving, and fuel consumption spikes, causing long-term wear. Short-distance moves might be manageable, but avoid highways or congested areas. The safest approach is to stop immediately, shut off the engine, check coolant levels, and call a tow truck for professional repairs. Delaying can turn a minor issue into a major one and risk damaging more components.
From my perspective, a faulty thermostat might still allow the car to move, but don't naively assume it's harmless. It regulates coolant flow, and a malfunction can lead to temperature control issues: if it's stuck closed, the engine can overheat instantly; if stuck open, the water temperature won't rise properly, leading to high fuel consumption and poor performance. I've seen owners who pushed their luck face painful consequences—major engine repairs and parts replacement costing tens of thousands. Temporarily driving a couple of kilometers might be possible in an emergency, but keep a close eye on the temperature gauge and stop immediately if it shows abnormalities. Get to a repair shop as soon as possible to diagnose the issue—replacing the thermostat is neither expensive nor complicated. Ignoring it can damage other systems like the water pump or radiator, leading to even higher costs and more downtime. Proper vehicle maintenance is taking responsibility for both your wallet and safety.
