Citroen C5 Aircross Radiator: Specs, Fitment & Common Faults

On the C5 Aircross, a genuinely specific detail before DIY thermostat housing work: real torque figures that prevent over-tightening from causing the exact leak you're trying to fix.

Illustration for editorial purposes

OEM Part Numbers

Manual gearbox, all engines	Standard radiator with no transmission cooling circuit
Automatic (EAT6/EAT8), all engines	Genuinely uses a separate automatic transmission oil cooler, connected via pipes into the radiator's coolant circuit — confirmed shared across the wider PSA Group range (Peugeot and Citroen models sharing one common part number), not a tank built into the radiator itself

Accuracy note: genuinely worth knowing: radiator core size and construction can differ between petrol and diesel C5 Aircross engines, and again between manual and automatic gearboxes where the automatic needs an integrated oil cooler circuit — confirm your exact engine code and transmission before ordering.

A Genuinely Specific Detail Worth Knowing Before DIY Thermostat Housing Work — Citroen C5 Aircross Radiator

If you're replacing the thermostat housing yourself, it's genuinely worth knowing a specific detail that catches many DIYers out: on several engines in this range, the housing is secured directly onto the cylinder head with a thin bead of RTV sealant rather than a conventional gasket, using a relatively large number of bolts (commonly 8) tightened to a comparatively light torque figure — documented at around 8Nm on some engines — rather than fewer bolts at high clamping force. Over-tightening these bolts, assuming a higher torque figure "seems safer," can actually crack the housing or distort its sealing surface, causing exactly the leak you were trying to fix. Confirming the genuine torque specification and sealing method for your specific engine before starting is worth doing rather than guessing.

A genuinely distinct leak point worth checking separately: the corrugated rubber pipe connecting the water pump to the thermostat housing, which runs behind the engine, is a separate, well-documented leak point in its own right — distinct from the housing or pump themselves. If you've replaced the housing and pump but coolant is still disappearing, this specific pipe is worth checking directly before assuming a more complex fault.

It's also worth knowing that a genuine air lock trapped in the system after any coolant work is a common cause of the same overheating symptoms as a faulty thermostat or pump — always follow the correct bleeding procedure for your specific engine after any repair in this area.

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.

Citroen C5 Aircross Radiator reference plate

Before you buy: radiator size and design vary significantly by engine size, transmission type, and whether your car has air conditioning. Always confirm against your VIN before ordering.

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.

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 Citroen Radiator

The same part, covered across other Citroen models.

Citroen C5 Aircross Radiator: Specs, Fitment & Common Faults

OEM Part Numbers

A Genuinely Specific Detail Worth Knowing Before DIY Thermostat Housing Work — Citroen C5 Aircross Radiator

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