Why is my Mercedes-Benz radiator leaking coolant even after replacing the radiator cap?

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Why is my Mercedes-Benz radiator leaking coolant even after replacing the radiator cap?

I own a Mercedes C-Class W204, and I recently noticed coolant leaking from the radiator area. I changed the radiator cap, thinking it might be a pressure issue, but the leak continues. Could it be a cracked radiator tank, faulty hoses, o r a weak water pump? This car is a Japanese import and used daily in Lahore’s traffic. What are the common causes of radiator leaks in Mercedes in Pakistani climate?

Talha Kyanii asked on 11 Oct 2025 10:46:33 am

1 Answer

9 views |

Gari Master - on 11 Oct 2025 10:47:43 am

If your Mercedes radiator continues to leak even after replacing the cap, several other common issues could be the cause, especially under Pakistani conditions:

Cracked Radiator Tank Plastic/Aluminum: Many Mercedes models use radiators with plastic top tanks that can crack due to heat cycles. Lahore’s high temperatures and stop-and-go traffic can speed up this wear.

Old o r Brittle Radiator Hoses: On used Japanese imports, the rubber hoses often get brittle with age and may start leaking from the ends o r clamps.

Radiator Core Leaks: Over time, the metal core can corrode due to use of low-quality coolant o r hard water, which is common when servicing from non-authorized workshops.

Water Pump o r Thermostat Housing: Sometimes, coolant leaks appear to be from the radiator but actually come from a nearby component like the water pump o r housing gasket.

What to do:

Get a cooling system pressure test to pinpoint the leak.

Inspect the radiator tanks and hose joints closely.

Use only genuine o r OEM-quality parts avoid temporary solutions like leak stop additives.