Citroen Relay Cooling: Buy Genuine & Aftermarket Parts

The radiator, which sheds heat to the air. The water pump, which keeps coolant moving. The thermostat, which holds the engine at operating temperature and opens to the radiator when needed. And the electric fan, which provides airflow when road speed cannot. Around those sit the expansion tank, the hoses and the temperature sensors. Radiators typically run R1,800-R4,550 depending on model, water pumps R800-R2,450.

Thermostat housings are a recurring one — many are plastic and they warp and weep with age. Expansion tanks crack at the seams. Water pumps fail on the belt-driven engines, which is why they get done with the timing belt. On the 1.6 HDi diesels, an EGR cooler failure can push exhaust gas into the coolant, which shows up as pressurisation and coolant loss with no external leak. Local water quality accelerates internal scaling, so a flush every few years genuinely pays for itself at R650-R1,200.

Usually the temperature gauge doing something it did not used to do — creeping up in traffic, or swinging rather than sitting steady. Coolant needing regular topping up is the other early sign, and it matters even when you cannot find a leak, because that often means it is going somewhere internal. Do not drive on it. A head gasket repair runs R7,600-R15,150 and a seized engine costs considerably more than that, so an overheating car is a stop-and-check situation rather than a get-home-first one.

The radiator does the heat exchange, but it only works as part of a system. The pump has to circulate, the thermostat has to open, the fan has to cut in, and the coolant has to be in good condition and at the right level. That is why chasing an overheat by replacing one part at a time is usually the expensive route. OEM radiators run R2,200-R5,250 with aftermarket from about R1,400, and roughly R800-R1,600 labour to fit.

Every three years or 60,000 km is the general guidance, and South African conditions make the shorter end of that sensible — every two years or 40,000 km if the car lives in heat and traffic. Use coolant that meets the PSA specification for your engine and do not mix types, because incompatible coolants can gel and block the fine passages in the radiator and heater core. Top up with the correct premix, never plain tap water. A professional flush and refill costs R650-R1,200.