A coolant flange is the housing bolted to the cylinder head or the block where the coolant leaves or enters the engine. It carries the stubs for the radiator and heater hoses, often the thermostat, and a boss for the temperature sensor. Older engines used cast aluminium; most engines built since the 1990s use a glass-fibre-reinforced plastic housing with an O-ring or a moulded seal against the engine.
Plastic flanges are a common source of coolant loss on cars past their first decade. The plastic ages in the heat at the back of the engine until a hose stub cracks or the joint face distorts; the seal hardens at the same time. The leak is small and evaporates on the hot engine, so the first sign is often the coolant smell and a slowly falling level in the expansion tank rather than a puddle.
KRONTEK coolant flanges are made to OEM-compliant quality and as aftermarket spare parts: the shape, the hose ports, the sensor boss, the bolt pattern and the seal of the original, so the flange fits the original hoses and sensor.
The range covers European and Japanese passenger cars. Each reference is identified by the OE number of the original part; send that number and the vehicle identification number (VIN) and we confirm the matching KRONTEK reference.
For availability and OE cross-references, contact us by email.