We take many enquiries about "cleaning out" or "flushing" of car radiators. Some people are surprised at what we tell them, as many are under the impression that "cleaning" the radiator is just flushing water through the system and that this can be done at home. This is not always so.


The following de-mystifies our terminology of cleaning a radiator:


  • Reverse Flush – flushing the system in a reverse direction from normal flow, generally using water pressure similar to a garden hose, to attempt to dislodge particles in the radiator. This will only remove floating particles and dirty water in the system.


  • Power Flush/Engine Flush – removal of thermostat and using high volume water and pressurised air. This also will not necessarily clear blocked radiator tubes but will ensure all coolant and loose deposits are removed from the engine and the radiator. Both of these types of flushing can be performed with the radiator in-situ or removed.


  • Radiator Cleanout (some people also call this a flush-out!) – the radiator needs to be removed from the vehicle for this exercise. The inlet tank (also called the "top" tank) is disassembled from the radiator core and each individual tube in the core is cleared of blockages to ensure complete flow across the whole radiator. The inlet tank is then replaced, and pressure tested for leaks. This process will bring the radiator back to an optimal performance level.


  • Chemical cleaning – this involves running a chemical cleaner through the system to break down and remove scale in the block. This is especially important for aluminium radiators to help prevent electrolysis problems.


  • External cleaning – it is also important to ensure that the external face of the radiator is kept free from debris (i.e. insects, grass seeds, etc). Due to compact engine space in modern vehicles, the radiator is usually required to be removed from the vehicle and high pressure blasting is used.

Radiator Tank removed from an overheating vehicle; a buildup of contaminants have caused a solid blockage in the bottom half of the radiator, which is a very common cause of overheating and radiator failure.


Typical components of a radiator