Can a faulty thermostat cause my BMW 2 Series to overheat?

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Can a faulty thermostat cause my BMW 2 Series to overheat?

My BMW 2 Series is overheating, and someone suggested that the thermostat might be stuck. How does a faulty thermostat cause overheating, and how can I test if it’s working properly?

Garitips asked on 19 Feb 2025 14:58:28 pm

1 Answer

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Garitips - on 19 Feb 2025 15:03:28 pm

Yes, a faulty thermostat is a common cause of overheating. The thermostat controls coolant flow between the engine and the radiator. Here’s how it can fail:

Stuck Closed: If the thermostat doesn’t open, coolant cannot circulate, leading to rapid overheating.
Stuck Open: If it stays open, the engine may take too long to warm up, reducing efficiency and causing poor fuel economy.
Delayed Opening: If the thermostat opens later than it should, it may allow the engine to overheat before coolant starts circulating.
How to Test a Thermostat:

Start the car and let it warm up.
Feel the upper radiator hose. If it stays cool while the engine overheats, the thermostat is likely stuck closed.
You can also remove the thermostat and place it in hot water to see if it opens at the correct temperature around 90°C – 105°C for most BMWs.
Solution:
If the thermostat is faulty, replace it with a BMW-approved part to prevent further overheating.