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Dayco: Surely a thermostat’s a thermostat, right?

By autotech-nic on February 24, 2021

As technicians are very aware, for vehicle manufacturers (VMs), every design decision is driven by the need to reduce engine emissions and moderate fuel consumption and this means vehicles are becoming far more interconnected and complex.

The modern cooling system is no different and plays a crucial part in the process, as the demands for increased efficiency, together with factors such as higher flow rates, turbocharger technology, autonomous heating and air conditioning, have transformed the traditional process of engine cooling into a sophisticated system.

Effective thermal control in all areas of the engine from initial start-up until reaching its designed operating temperature, whether in hot spots such as around the cylinder head or cooler zones elsewhere, is vital in order to maintain the VMs claimed emissions figures, and although easily overlooked, it is the humble thermostat that ensures that this is correctly managed.

Problems and solutions

Although generally reliable, AASA 2020 report data show that over a five-year period from 2014, the average thermostat failure rate has steadily increased to almost 5%. At the same time, the percentage of vehicles fitted with integrated thermostat housings and MAP thermostats, rather than a traditional thermostat design, has grown from 55% to 80%.

The 1.4 and 1.6-litre petrol and 1.6-litre diesel engines used in the second generation (R56/57) Mini feature a thermostat housing that is prone to be the source of leaks in the coolant system. These problems are generally caused by either excessive heat from the exhaust manifold or oil contamination. It also not uncommon for the thermostat valve to stick, which can result in overheating.

Integrated housings like this are complex products and this directly affects their predicted service life and crucially, their cost, which is why they should not be considered an ‘anything will do’ product as the quality will directly affect both their ability to operate within the VM’s strict performance parameters and their expected service life, so OE quality must be the benchmark.

Dayco’s extensive technological know-how and drive to ensure its products deliver to the highest levels of performance means that a combination of precision couplings and quality materials has enabled the company to supply a comprehensive range of thermostats that are of OE standard in their quality, safety, efficiency and durability.

For more information regarding OEM quality thermostats or the power transmission products in the Dayco range, please email: or visit:



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Autotechnician is a magazine published nine times a year, delivering essential information to independent garage owners and technicians in the UK. Delivered both digitally and in print, autotechnician provides readers with technical, training, business advice, product and news, allowing our readers to keep up to date with information they need to run and work within a modern workshop.
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