Vauxhall Astra Radiator: Specs, Fitment & Common Faults

A specific, documented crack point on the thermostat housing causes coolant leaks that genuinely stump dealers — plus a filling technique that prevents air pockets mimicking the same symptoms.

Illustration for editorial purposes

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OEM Part Number: 13453905 (as quoted in catalogue listings — confirm via VIN) — aftermarket radiators Nissens 630797 / Denso DRM20118

Accuracy note: Covers the Vauxhall Astra (K 2015-2021) as listed in the UK aftermarket catalogues. Radiators are sold by engine, gearbox and air-conditioning fitment, and one model usually has two or three different cores — a thicker core for diesels and automatics, a thinner one for small petrols — with different hose positions, so a radiator for the wrong engine will not connect up. The references below are UK aftermarket listings whose fitment lists name this generation, labelled by brand with the core size in mm; genuine numbers are those quoted against the listing. Check your engine code and whether the car has air conditioning against your VIN, and replace the coolant and bleed the system after fitting.

Radiators (aftermarket)	Nissens 630797 (680 x 306 x 26 mm, soldered aluminium core with plastic tanks, fits 1.0 Turbo 90 and 105 PS, 1.2 Turbo 110, 131 and 145 PS, 1.4 Turbo 125, 145 and 150 PS and 1.4 CNG 110 PS); Valeo 701376 / 701766; Denso DRM20118; Mahle CR 2251 000P / CR 2699 000P; NRF 550144; Van Wezel 37012704; Hella 8MK 366 300-451; Delphi RA20272. For the non-turbo petrol: Nissens 630798 (680 x 388 x 16 mm, soldered aluminium core with plastic tanks, fits 1.4 100 PS, engine code B14XE)
Core sizes & variants	Turbocharged petrols take the 680 x 306 x 26 mm radiator; the basic 1.4 non-turbo takes a taller, thinner 680 x 388 x 16 mm unit.
Genuine (OE) numbers quoted	13453905; 39095604 (1.4 non-turbo)
Fitment notes	Both radiators have 38.5 mm connections; no seals listed. Diesel owners should order against the VIN.

Accuracy note: genuinely worth knowing: automatic gearbox Astras typically need a radiator with a built-in transmission oil cooler that manual versions don't have — ordering the manual-spec part for an automatic car will fit, but won't cool the gearbox oil properly.

A Genuine, Specific Weak Point Worth Checking First: The Thermostat Housing Connector — Vauxhall Astra Radiator

If your Astra J has a persistent coolant leak that's proven difficult to pin down — including cases where the car has been back to a dealer multiple times without a leak being found — it's genuinely worth checking the hard plastic pipe connector on top of the thermostat housing, which feeds heating to the throttle body. This is a push-fit connection that has a documented tendency to crack, and because the leak often only shows up once the system is pressurised and hot (rather than when the car's sitting cold), it can be genuinely difficult for a garage to spot during a quick inspection. If you've had persistent, hard-to-locate coolant loss and a straightforward pressure test hasn't found anything obvious, ask specifically about this connector before accepting "no leak found" as the final answer.

A genuinely useful filling technique: air pockets trapped in the cooling system during a refill are a common, underappreciated cause of overheating symptoms and a coolant level that seems to disappear — filling too quickly is the usual cause. Adding coolant slowly, almost dribbling it in, gives trapped air a proper chance to escape rather than getting sealed into a pocket that later causes exactly the symptoms of a leak or failing thermostat.

Vauxhall Astra Radiator: The Part That Keeps Everything Else From Cooking

Few parts get less attention than this one, but on the Vauxhall Astra, 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.

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.

Vauxhall Astra Radiator: Watch: Replacing It

🎬 Watch: VAUXHALL/OPEL Astra H radiator change (remove intercooler and electric fan). CDTi. 1.3 (older gen)

Watch on YouTube ↗

Astra H (2004-10); nothing for Astra K beyond grille/bumper removal

Vauxhall Astra Radiator: What It Does

On the Vauxhall Astra, 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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Vauxhall Astra 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 Vauxhall Radiator

The same part, covered across other Vauxhall models.