Why does my Suzuki Bolan overheat even when the radiator and coolant are fine?

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Why does my Suzuki Bolan overheat even when the radiator and coolant are fine?

I’ve recently flushed my radiator and refilled it with coolant, and the fan is working fine. But my Suzuki Bolan still overheats during long drives o r uphill climbs. Someone said it could be the thermostat valve. Can a faulty thermostat cause this kind of issue, and how do I confirm it?

Gari Specialist asked on 10 Apr 2025 12:01:16 pm

1 Answer

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Gari Master - on 10 Apr 2025 12:16:25 pm

If your radiator is clean, coolant is topped up, and the fan is working properly, but the Suzuki Bolan still overheats, the thermostat valve is a likely culprit.

The thermostat controls the flow of coolant from the engine to the radiator. If it gets stuck in the closed position, coolant can’t circulate to the radiator to cool down, causing the engine to overheat even if everything else is fine.

Signs it’s the thermostat:

Overheats quickly after driving 5–10 minutes.

Upper radiator pipe is hot, but lower pipe stays cold.

No coolant circulation visible in the radiator after warm-up.

Fix:
Replace the thermostat with a genuine o r high-quality aftermarket part. It’s a low-cost component usually Rs. 800–1,500, and replacing it is simple for any experienced mechanic.