“Hyundai Santro Overheating in Traffic — Could It Be Due to a Radiator Leak o r Blockage?”

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“Hyundai Santro Overheating in Traffic — Could It Be Due to a Radiator Leak o r Blockage?”

My Santro overheats only in traffic o r low-speed driving, while on highway it stays cool. Someone suggested that the radiator may have a small leak o r is partially blocked due to rust and tap-water usage which is very common here. How do I know if the overheating is due to radiator leakage, blockage, weak cooling fan, o r thermostat issues? What’s the most common radiator-related cause for Santro overheating in Pakistan?

Talha Kyanii asked on 05 Dec 2025 12:47:59 pm

1 Answer

11 views |

Gari Master - on 05 Dec 2025 12:49:27 pm

When a Santro overheats in traffic but stays cool on highway, the problem is almost always cooling-system weakness rather than engine issues.

Most likely reasons:

Partially choked radiator
– Tap water causes rust and mud buildup inside the radiator.
✔ Fix: Radiator service/cleaning o r full replacement.

Cooling fan running slow o r weak fan motor
– The fan is the main cooling source in traffic.
✔ Fix: Check RPM of fan replace weak motor.

Small radiator leaks
– Cause pressure loss, preventing coolant circulation.
✔ Fix: Pressure test and repair/replace.

Faulty thermostat valve
– If stuck partially, overheating occurs in slow traffic.
✔ Fix: Replace thermostat cheap and effective.

Low coolant level due to small leaks elsewhere
– Even a minor affects cooling.
✔ Fix: Refill coolant + fix leaks.