The coolant hoses that carry coolant to and from the engine are critically important parts of any engine’s cooling system, but as with many other critically important systems and components, coolant hoses are also the subject of fierce debates. One such debate revolves around the issue of whether rubber or silicone is the better material, and while there is no clear winner, each type of hose has some advantages and disadvantages depending on the application. Below we discuss the trade offs between rubber versus silicone radiator hoses by comparing the pros and cons of each type.
Rubber radiator hoses have evolved greatly over the last thirty years or so in terms of both their construction and the materials. For instance, unlike radiator hoses made thirty years ago that contained significant percentages of unstabilized natural rubber, modern radiator hoses are most often made from EPDM (Ethylene Propylene Diene Monomer) rubber compounds.
The main advantages of these compounds include high tensile strength, high resistance against tearing, high perforation resistance, and their high inherent resistance against degradation by UV radiation and ambient ozone. As such, these properties make these compounds ideal materials to use in the manufacture of automotive radiator hoses since they create long lasting hoses. In addition to these inherent properties, OEM manufacturers of radiator hoses often also add braided polyester or steel reinforcing layers, as well as several inner and outer layers or coatings to protect the rubber against the effects of acids and stray electrical currents in coolants.
Pros Of Rubber Radiator Hoses
• Most OEM rubber radiator hoses are rated to cope with maximum coolant temperatures of around 2570F, which is significantly higher than the temperature of the coolant in engines that function normally.
• The advanced chemical formulation and properties of rubber radiator hoses combine to give modern rubber hoses useful lives of six years, and often much longer.
• The high density of EPDM materials translates into very low permeability rates, which largely prevents good quality engine coolant from evaporating through the walls of rubber hoses over time.
• Rubber radiator hoses are at least one order of magnitude more cost-effective (aka much cheaper) than comparable silicone hoses.
Cons Of Rubber Radiator Roses
• Low resistance against chemical attack by hydrocarbons, such as from oil and fuel leaks. Contact with fuel and oil vapors usually leads to a rapid deterioration of EPDM compounds, with typical symptoms being swelling and softening of the hose walls. This can ultimately lead to hose failure if not replaced in a timely fashion.
• Lose flexibility over time and degrade, making them more prone to cracking or rupture with age.
High-quality silicone hoses that are made by reputable manufacturers are typically made from pure silicone that is either molded or extruded to exact specifications and dimensions. However, high-quality silicone radiator hoses will invariably contain one or more layers of braided polyester as a means of reinforcing the hose walls, and in some cases, silicone hoses may also contain steel wire reinforcements to prevent the hose from collapsing under suction conditions (such as when an engine cools down rapidly). As a practical matter, silicone radiator hoses are viable direct-fit replacements for rubber hoses.
Pros Of Silicone Radiator Hoses
• Most high-quality silicone radiator hoses are safe to use with coolant temperatures as high as 350°F (although most thermostats for roadgoing vehicles open at temperatures well below this). However, it should be noted that by the time the engine coolant reaches this temperature the engine has almost certainly suffered fatal heat damage already, which makes the high-temperature rating moot in most applications.
• Silicone radiator hoses are available in various colors, which is great if you want to add style and flair to your car’s engine bay.
• Silicone maintains its flexibility more readily and in harsher conditions than rubber hoses.
Cons Of Silicone Radiator Hoses
• While silicone is described as inert, in the sense that it does not readily react with other substances, silicone is not resistant to chemical attack by fuel and oil.
• Silicone hoses are not only much more expensive than comparable rubber hoses, but silicone hoses also require special hose clamps to prevent damage to the hose ends during installation onto your radiator as well as to maintain effective sealing at the connections.
• Silicone hoses have permeability rates that are significantly higher than those of comparable rubber hoses, which can translate into significant coolant losses over extended periods, requiring more frequent refills.
Are Rubber Or Silicone Radiator Hoses Better?
There is no simple answer to this question since both high-quality rubber and silicone hoses that are properly installed perform equally well in the vast majority of situations.
Nonetheless, given the high cost of silicone radiator hoses, there is little point in replacing OEM rubber hoses on a vehicle that is never subjected to extreme conditions, or whose rubber radiator hoses are less than four to five years old and free of mechanical damage.
That said, there are certain instances where silicone hoses make sense. Specifically, if you are trying to dress up your engine bay, they may be worth the cost. Additionally, on average they will last longer than rubber radiator hoses, so if you intend to keep your car for the long haul, you may enjoy less frequent radiator hose replacements if you opt for silicone.
Given that OEM rubber radiator hoses usually come with meaningful warranties, careful consideration must be taken before replacing OEM rubber hoses with aftermarket silicone hoses. Often, silicone hoses do not come with any sort of warranty at all, despite the price increase.
Overall, our general recommendation when it comes to choosing a rubber versus silicone radiator hoses is to stick with rubber hoses as the high value option unless your specific situation warrants switching to silicone. That said, if you are modifying your vehicle and silicone hoses meet your performance or style preferences, there is certainly nothing wrong with going with a set of silicone radiator hoses if you can justify the trade offs.