Radiator & Fans

Because at road speed the vehicle's motion supplies airflow through the radiator and in traffic the fan has to, so a symptom that appears only when stationary points squarely at the fan, its control or its supply. Watch whether the fan runs as temperature rises, and check the fuse, the relay or the control module output before condemning the fan. This is one of the most reliable diagnostic patterns in cooling, and it saves ordering radiators that were never at fault.

Two ways, and both are common. Externally the fins clog with leaves, insects and road debris, particularly on the face you cannot see behind the condenser, which reduces airflow while the core looks intact from the front. Internally, corrosion products and sealant residue narrow the tubes, so coolant flows through fewer of them and heat transfer falls. An infrared thermometer across the core reveals cold sections quickly, which is a better test than looking at it.

Because different components want different temperatures. A drive unit and its power electronics tolerate and produce far more heat than a traction battery, which needs a much lower and more tightly controlled temperature, so vehicles run separate circuits with separate radiators, arranged so the coolest air reaches whichever core needs it most. That is why the listings distinguish motor, inverter and high temperature radiators, and why fitting one in the wrong position produces a thermal fault rather than a visible error.

Older copper and brass cores could be soldered by a specialist, and modern aluminium cores with plastic end tanks generally cannot be repaired to any useful standard. The common failure is the crimped joint between the core and the plastic tank, which fails from heat cycling, and no sealant or patch restores it reliably under pressure. Radiator sealant added to the system is worse still, since it blocks the narrow passages elsewhere that you were relying on.

Because a radiator is a fragile assembly hanging in the front of a vehicle that vibrates constantly. The rubber bushes at its mounts isolate it from that vibration, and once they perish and the core sits hard against metal, the stress concentrates at the end tanks and the crimped joint cracks. That is a common cause of a radiator that leaks a few years after being replaced. Fit new bushes and brackets with any radiator, since they cost very little.

Bushes, brackets and small fittings sit right at the bottom of the range. Electric cooling fans are moderate. Radiators, motor and inverter radiators and oil coolers cost the most in this category, and they ship as bulky, easily damaged items. The live minimum and maximum are shown in the band at the top of this page. Because a dead fan and a blocked core produce identical symptoms, testing before ordering matters more than usual here.

On an accessible vehicle, yes, and the work is draining, releasing hoses and connectors, and lifting the core out of its mounts. The difficulties are access, since the front bumper and undertray often need removing, and afterwards the bleed procedure, which on multi circuit vehicles may require a scan tool to run pumps and cycle valves. Handle the core carefully, since fins bend at a touch and a damaged face reduces airflow before you have even fitted it.

Not necessarily. Modern fans are variable speed and network controlled, so a fan running quietly at low duty for long periods is normal behaviour, and on electrified vehicles it may run after shutdown or during charging when there is no airflow at all. What is not normal is a fan running at full speed continuously from cold start, which usually indicates the control unit has lost a temperature signal and defaulted to maximum cooling as a protective measure. Have the codes read.

It sits in the same stack and does the same kind of job for a different fluid. An oil cooler transfers heat from engine or transmission oil into either air or coolant, keeping the oil within a temperature band where its viscosity and protection remain correct. Failures show as oil in the coolant or coolant in the oil on liquid to liquid types, and as an external leak on air cooled ones. Both are listed here alongside the radiators.

Only where the OE number agrees. Core thickness, tank shape, connection positions and mounting points follow the specific vehicle and drivetrain, and on an electrified vehicle the same aperture may hold different cores for different circuits. A radiator that fits the space but has the wrong capacity leaves the vehicle running warm under load without an obvious fault. Match the number, and use the quote form where the reference brings back nothing.

Yes, and gently. Debris packed between the condenser and the radiator restricts airflow substantially and is invisible from the front, so it is worth separating the stack occasionally on a vehicle that has covered distance in summer. Use low pressure water or air from the engine side outward, never a pressure washer, which folds the fins flat and does more damage than the debris. Straighten bent fins with a proper comb rather than a screwdriver.

Yes. Radiators and fan assemblies are bulky, easily damaged in transit and built to one cooling package, so the delivered figure is worth having and the quote returns it. Send the number and your destination. Be careful about which radiator you are ordering, because an electric vehicle can carry a motor radiator, a high temperature radiator and an inverter radiator that look broadly alike and serve different loops. Add the mount bushings and the shroud clips to the request, since the rubbers perish and a radiator sitting on hardened mounts cracks its side tanks.