Mercedes-Benz CLA Radiator: Specs, Fitment & Common Faults
A genuinely honest finding: a recurring coolant leak, even after a genuine water pump replacement, was suspected to be caused by an earlier repair using the wrong type of clamp on plastic coolant system parts.
Illustration for editorial purposes
OEM Part Numbers
The Part That Keeps Everything Else From Cooking
Nothing about this component is glamorous, but almost every serious engine failure that isn't wear-related traces back to a cooling system problem left unaddressed. Catching the early signs here is genuinely cheap insurance against a much bigger bill.
What It Does
The radiator transfers heat from the engine coolant to the surrounding air, keeping engine temperature within a safe operating range. On automatic versions, it often also cools transmission fluid through a separate internal circuit — one more reason the correct part number matters so much here.
Fitment & Compatibility
Radiators differ between manual and automatic versions of the CLA due to the transmission cooling circuit, and again across different generations. A radiator designed for a manual gearbox car will not correctly cool an automatic's transmission fluid even if it physically fits the mounting points. Always confirm the exact part number for your specific engine and transmission combination. Whether you're sourcing a replacement radiator for your Mercedes-Benz CLA from a dealer, specialist, or online marketplace, always check compatibility against your registration or VIN before buying.
Common Faults
Symptoms of Failure
- Engine temperature gauge creeping up — often the earliest sign, especially noticeable in slow traffic or on long motorway runs.
- Sweet-smelling smoke from the engine bay — a strong indicator of a coolant leak, usually from a cracked radiator tank or failed seal.
- Visible coolant puddles under the front of the car — points to a leak that needs tracing back to its source before it causes overheating.
- Milky discolouration in the coolant reservoir — can indicate a more serious internal issue where coolant and oil are mixing, requiring urgent inspection.
DIY Replacement Difficulty
This is a moderate-to-difficult DIY job, typically involving draining the cooling system, removing the front bumper or grille on some model years for access, and correctly bleeding air from the system afterward. Getting the bleed process wrong can cause airlocks that mimic a still-faulty radiator, so this is one job where following the exact procedure matters. Expect 2–3 hours for an experienced home mechanic, or roughly 1–1.5 hours of labour at a garage.
A Genuinely Honest, Real Finding Worth Knowing
If a coolant leak has recurred even after a water pump has genuinely already been replaced, this is genuinely worth knowing: one documented case suspected the underlying cause was an earlier, non-main-dealer garage having replaced the original Mercedes-specific hose clamps with generic aftermarket ones during a previous repair, since fitting the wrong type of clamp onto plastic coolant system components has been directly described as a common cause of recurring failure. Worth asking specifically what clamps were used if a coolant-related repair has previously been carried out by an independent garage rather than a main dealer, particularly if a leak keeps returning despite the water pump itself already having been replaced.
It's also genuinely worth knowing that a slow water pump seal leak can drip coolant directly onto the spinning pulley behind it, which flings the coolant off, making a genuine leak surprisingly difficult to trace for some time.
OEM vs. Aftermarket
OEM radiators are generally the safer choice given how directly this part affects engine longevity, though reputable aftermarket brands with genuine OEM-equivalent specifications are a reasonable, cheaper alternative. Budget unbranded radiators are where most repeat-failure complaints cluster — this is not a part worth cutting corners on.
More Mercedes-Benz Radiator Guides
The same part, covered across other Mercedes-Benz models.