The coolant expands as the engine warms up. The expansion tank, also called the coolant reservoir or header tank, takes up that extra volume and gives it back as the engine cools, so the system stays full without air. On most modern cars the tank is the highest point of the circuit and carries the pressure cap, the level marks and often a level sensor; on older designs an unpressurised overflow bottle sits beside a radiator with its own cap.
The tank is a moulded plastic part that lives in the heat of the engine bay and in contact with hot coolant. Over the years the plastic darkens, hardens and finally cracks at a seam, at the neck or at a hose stub. The leak is small at first and appears only when the system is hot and pressurised, which is why a car can lose coolant for months with no puddle under it.
KRONTEK expansion tanks are made to OEM-compliant quality and as aftermarket spare parts: the shape, the hose fittings, the sensor boss and the mounting of the original, so the tank fits its bracket and the original hoses without adapters.
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.