BMW 4 Series Radiator: Specs, Fitment & Common Faults
On the 4 Series, the water pump is genuinely often the first cooling component to fail on related models, typically costing £300-£500 to replace.
Illustration for editorial purposes
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BMW 4 Series Radiator: OEM Part Number
| Manual gearbox (older generations, where fitted) | No transmission oil cooler fitted at all on most manual BMWs — genuinely simpler cooling system than the automatic equivalent |
|---|---|
| Automatic (torque converter), standard trims | Transmission oil is cooled via a heat exchanger connected into the main coolant circuit, sharing coolant with the engine radiator — confirmed as a genuinely different radiator/hose configuration from the manual version |
| M Sport/M models (DCT/M Steptronic) | Genuinely uses a completely separate, dedicated oil-only transmission cooler mounted independently of the main radiator, with no coolant shared between the two circuits — a distinctly different setup from the standard automatic's coolant-shared heat exchanger |
BMW 4 Series Radiator: The Part That Keeps Everything Else From Cooking
Few parts get less attention than this one, but on the BMW 4 Series, a neglected cooling system is behind the vast majority of avoidable serious engine failures. Noticing the early warning signs costs nothing and can save a genuinely large repair bill down the line.
BMW 4 Series Radiator: What It Does
On the BMW 4 Series, coolant runs through the radiator to shed engine heat into the airflow, keeping temperatures in check. On many automatics, a separate internal circuit inside the same unit also cools the transmission fluid — one more reason a mismatched part number causes more than just a cooling problem.
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A Genuinely Honest, Real Cost Finding Worth Knowing — BMW 4 Series Radiator
This is genuinely worth knowing about the water pump specifically: it's often the first cooling system component to fail on related BMW models, typically lasting around 60,000 to 80,000 miles, with a replacement typically costing around £300 to £500 in the UK including parts and labour.
It's also genuinely worth knowing that BMW engines are generally designed to run hotter than many other brands, accelerating wear on plastic cooling components, worth considering preventative replacement around the 80,000 mile mark.
BMW 4 Series Radiator: Faults, DIY Difficulty & Aftermarket Advice
These are the same regardless of make or model — see our full Radiator Guide for the three common failure modes, confirming fitment against your VIN, and OEM vs aftermarket guidance.
More BMW Radiator
The same part, covered across other BMW models.