Hyundai i30 Radiator: Specs, Fitment & Common Faults

On the i30, a leak specifically from the weep hole near the A/C compressor genuinely points toward a failing water pump seal.

Illustration for editorial purposes

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OEM Part Number: 25310G4300 (as quoted in catalogue listings — confirm via VIN) — aftermarket radiators Nissens 636728 / Denso DRM43023

Accuracy note: Covers the Hyundai i30 (2017-) 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 636728 (648 x 291 x 26 mm, aluminium core with plastic tanks, fits 1.0 T-GDi G3LC/G3LE, 1.4 T-GDi G4LD, 1.5 DPI G4LG and 1.5 T-GDi 48V G4LK); Nissens 606739 (648 x 291 x 26 mm, aluminium core with plastic tanks, fits 1.6 CRDi D4FB 95/110/128/136); Denso DRM43023; Mahle CR 1975 000P; Van Wezel 82012734 (petrol) and 82012735 (diesel); NRF 550034 (diesel).
Core sizes & variants	Petrol and diesel radiators are the same size with 35 mm connections but carry different part numbers; the petrol unit (OE 25310G4300 / 25310F3300 / 25310J7800) is shared with the Kia Ceed CD, Proceed and XCeed, and the diesel unit (OE 25310F2200) is shared with the Elantra AD 1.6 D.
Genuine (OE) numbers quoted	25310G4300; 25310F3300; 25310J7800; 25310F2200
Fitment notes	Both radiators are supplied with gaskets and seals. Order by fuel type rather than by dimensions, since the two cores measure the same.

Accuracy note: genuinely worth knowing: automatic gearbox i30s 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 Genuinely Useful Diagnostic Detail Worth Knowing — Hyundai i30 Radiator

If you're trying to pin down exactly where a coolant leak is coming from, this is genuinely worth knowing: a leak specifically from the small weep hole in the engine block near the A/C compressor points toward a failing water pump seal rather than a more general leak elsewhere.

A genuinely honest point worth knowing even after a recent water pump replacement: if a leak returns despite a relatively recent replacement, internal seals or bearings within even a new pump can occasionally be compromised, or the pump can be damaged by an unrelated issue. It's worth checking the timing belt tensioner and pulleys for wear at the same time, since improper belt tension can itself damage an otherwise sound water pump.

It's also worth knowing that the thermostat housing sits toward the front of the engine, higher up than where normal AC condensation would appear — worth checking this specific area if you're unsure whether water underneath the car is genuine coolant or harmless condensation.

Hyundai i30 Radiator: The Part That Keeps Everything Else From Cooking

It's an unglamorous part, but on the Hyundai i30, the cooling system is behind almost every serious non-wear engine failure that could have been prevented. Spotting trouble here early is about as cheap an insurance policy as exists against a genuinely expensive repair bill.

Hyundai i30 Radiator: Watch: Replacing It

🎬 Watch: How to change the radiator and coolant on the HYUNDAI I30 CW [AUTODOC TUTORIAL] (older gen)

Watch on YouTube ↗

Autodoc video on the i30 CW estate (pre-2017); nothing found on the PD generation

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.

Hyundai i30 Radiator: What It Does

On the Hyundai i30, heat from the engine coolant is shed to the surrounding air through the radiator, keeping engine temperature in a safe range. On automatic gearboxes, it often doubles up, cooling transmission fluid through a separate internal circuit too — which is why getting the exact part number right matters more here than on a simple heat exchanger.

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Hyundai i30 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 Hyundai Radiator

The same part, covered across other Hyundai models.