SR Silicone Hoses
They may not seem an obvious upgrade, but silicone hoses can offer a great alternative to the standard OEM rubber fitted at the factory. You may have seen the Mods and Upgrades article in our January edition of Jaguar Enthusiast on suspension bushes which uses polyurethane as an alternative to rubber due to its durability. Much in a similar way we can replace rubber hoses that degrade with a more durable material, in this case silicone.
The use of silicone as an engineering material can be largely traced back to World War II. Silicone was used mainly for aviation purposes due to its unique chemical and thermal properties, including excellent high-temperature resistance, low temperature tolerance, and water resistance which made it ideal for applications like gaskets and O-rings in engines. Manufacturing of silicone tubing began in the 1960s and since then, it has become a material that is crucial to many modern industries, such as food and beverage, pharmaceuticals, and electronics. With this background it’s not then hard to see how it made the jump into the automotive industry.
As with other parts we have talked about in this series, silicone hoses are generally not fitted as OEM due to their slightly higher cost. Silicone hoses also have the potential to outlast the lifetime of a vehicle. Being cynical we could also say that manufacturers don’t want everlasting components as it’s not great for their parts business!
One of the main advantages of silicone over rubber is its ability to cope with higher temperature range, EPDM (ethylene propylene diene monomer rubber) rubber that is commonly used in coolant hoses has a maximum operating temperature of around 150 °C. Silicone can be formulated to operate between -65 and 350 °C. Silicone also has significantly better flame and chemical resistance than EPDM or natural rubber and is more durable and can operate at higher pressure. Silicone is also resistant to ozone, UV rays, and other environmental factors that can cause rubber hoses to deteriorate over time. Silicone hoses are smoother and have less resistance to coolant flow compared to traditional rubber hoses. This means that they can help improve the efficiency of the engine’s cooling system by allowing coolant to flow more freely and quickly. This can help prevent overheating and improve overall engine performance. It is for these reasons that silicone hoses are used wherever possible in motorsport applications. As with all our performance upgrades we like to test them on track, our last race car build, Jack’s XK8 features silicone hoses for cooling.
As with all cars there are certain hoses on Jaguars that suffer more common failures. The EPDM rubber that is generally used for coolant hose manufacturing commonly has a maximum lifespan of 10-15 years. In some cases, SBR or NBR rubber is also used. We have developed a range of hoses that covers the more problematic areas on Jaguars. An example would be the notorious V8 valley heater pipe. It not so much about the cost of the replacement part but reducing the chance of failure. If we are talking about a supercharged model, then this can result in more than day’s work to replace the valley pipe as the supercharger requires removal. The labour cost compared to the part cost therefore is extremely high so if we can eliminate the chance of future failure with a superior part then it makes sense to do so.
We have created a growing range of silicone hoses which are available through our online shop or we happy to fit them for you. Starting the range with hoses that we find are the most common to fail such as the thermostat housing hose to coolant inlet which is common to the V8 4.2 for XJ from 2003-2009, XK 2006-2009 (X150), XF from 2008-2009 and S Type R being a direct replacement for part number AJ811638. Another hose that commonly fails on the 4.2 XK (X150) is the block to elbow radiator hose AJ811062 and on the same model the radiator to gas recirculation (EGR) hose, AJ811064 we have manufactured both therefore with silicone alternatives.
One of the most complicated hoses in the Jaguar range and therefore one of the most expensive is the XK8/XKR X100 bottom hose. We have been able to produce a silicone equivalent to part number MJB4519AF for below the cost of the OEM part. This is a hose that is a regular replacement item and with a full flush of the system it can be up to two hours to fit, so fitting an upgraded silicone hose in this application make a lot of sense. As I said at the beginning of the article, silicone hoses may not be an obvious upgrade but as they reduce future maintenance it can be a sensible cost effective upgrade.
As Henry Ford once said “you can have any colour you like as long as it’s black” we haven’t ventured into fancy colours, so our silicone hoses come in one colour, but they do keep the engine bay looking fairly original. We have a lot of other silicone hoses in the range and are adding more you can check the full range on our online shop.
