Prevent water pump failure by flushing the cooling system


Why flush the cooling system

Proper flushing is one of the most critical elements of cooling system maintenance, yet it is often the most neglected service item in the workshop today. Inadequate flushing can lead to premature failure of newly installed parts, resulting in warranty problems and frustrated customers. Read all about how flushing the cooling system will positively affect the performance of the cooling system.

Coolant deterioration

Just like engine oil and transmission fluid, engine coolant deteriorates over time. It can also get contaminated with abrasive particles and foreign materials forming damaging deposits inside cooling hoses. A properly flushed system will remove those contaminants and deposits.

Mixing coolants

Besides damaging deposits, mixing coolants of different chemistries can lead to corrosion within the system. There are 4 main combinations used today and none of them are compatible. These coolant types work differently to protect the engine.

Inhibitor Technology
 Inorganic Additive Technology (IAT)  Silicate
 Organic Acid Technology (OAT)  Organic Acid – Silicate Free
 Hybrid Organic Acid Technology (HOAT)  Silicate & Organic Acid
 Phosphate Hybrid Organic Acid Technology (PHOAT)  Phosphate & Organic Acid

Inorganic additives are used to plate cooling system surfaces as they form a thick protective layer but deplete over time. They are not very selective, which means they cover all surfaces regardless of what these surfaces are made of. Organic additives form chemical bonds with vulnerable surfaces, making a thin though extremely stable protective layer offering longer protection. They are selective, targeting only the areas that need protection.

Coolant selection would be easy if all vehicle manufacturers developed their systems with the same materials. But as that is not the case, each manufacturer develops a factory fill coolant based on the cooling system component materials it contacts. So, choosing the proper replacement coolant is impacted by the cooling system design. That is why Gates recommends always replacing the vehicle’s coolant with the coolant recommended by the vehicle manufacturer.

How to flush properly

With a conventional drain, flush and refill much of the contaminated coolant and harmful debris is left behind. It also does little to address the problem of severe accumulated debris. A good flushing tool uses clean water and compressed air and cleans radiators, heat exchangers, hoses and engine blocks.

Make sure the flush is complete with the old water pump still in place. Flushing after the new water pump is installed can lead to premature failure due to particulates getting caught in the seals during the flush.

Looks can be deceiving

Sometimes coolant may look clean, but if the system has never been flushed and mileage is high, it is probably contaminated. Not all contaminants make the coolant look dirty. Sand and other abrasive debris particles, aluminium corrosion particles and mineral content in the water, to cite three examples, won’t be obvious to detect. Also, do not rely on the coolant colouring to make your pick. Coolants may have the same colour, even though ingredients are different. The function of the dye is to help you spot a coolant leak. The right answer to what coolant to use when, is: always use the vehicle manufacturer’s recommended coolant.