. Is it normal for the radiator in my Mercedes-Benz to leak after driving in hot weather o r city traffic?

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. Is it normal for the radiator in my Mercedes-Benz to leak after driving in hot weather o r city traffic?

My Mercedes E-Class W211 seems to develop coolant leaks after driving in city traffic o r during hot afternoons. I usually drive around Karachi, and the issue gets worse when the A/C is on. The leak is small but constant, and I see s under the car after parking. Is this a sign of radiator fatigue due to heat, o r could it be a minor seal o r hose issue? How common is this in Mercedes cars here?

Talha Kyanii asked on 11 Oct 2025 10:46:53 am

1 Answer

8 views |

Gari Master - on 11 Oct 2025 10:47:59 am

No, it is not normal for a radiator to leak in hot weather — it signals a weak point in the cooling system. However, in cities like Karachi, with constant heat and traffic, radiator stress is very common in Mercedes models:

Thermal Expansion Stress: Older o r aftermarket radiators may crack under pressure when heat builds up during slow traffic with the A/C on.

Worn-out Expansion Tank o r Cap: If the pressure relief system isn’t working often due to a faulty expansion tank cap, pressure builds up and forces coolant out.

Loose o r Leaky Hose Clamps: Heat expansion can cause poorly fitted clamps to leak, especially on cars not maintained with proper torque specs.

Radiator Fan Issues: If the cooling fan isn’t activating properly, the radiator overheats, increasing pressure and causing leaks.

What to do:

Check coolant level and look for white residue dried coolant around hose joints.

Replace the radiator if there are visible cracks o r leaks.

Check the radiator fan operation and thermostat functionality.