Thanks to compact engine compartments, air conditioning, turbocharging, and computer-controlled cooling fans, underhood operating temperatures have risen dramatically. To withstand these extreme temperatures, most modern coolant hoses are now made from ethylene propylene (EPDM rubber, which can endure operating temperatures ranging from -40 to +275 degrees F.

Thanks to extremely crowded engine compartments, about 90 percent of all automotive hoses currently produced are curved or molded to fit specific applications of vehicles, including “branched” hoses with three or more molded outlets. Coolant hoses are also manufactured in universal-fit straight lengths that can withstand up to 100 psi working pressures encountered in many commercial applications. Industrial applications can also benefit from shorter-length hoses specifically designed to absorb vibration and to correct for connector misalignment. Last, remember that many commercial applications require straight and molded silicone coolant hose that is rated to withstand temperature differentials ranging from -70 to +350 degrees F, which can be encountered on some over-the-road vehicles.

Hose Installation Tips
As you’ve probably guessed, cooling hose removal and installation techniques also have changed. Since EPDM coolant hoses tend to bond with metal connections like heater core inlet/outlet tubes, it’s always better cut, rather than twist or pull an old hose from its connection. If the hose is to be re-used, the technician should use a hose pick, which slips under the hose to separate it from its connection. Since a petroleum-based grease or oil can be harmful to the cooling system, any new coolant hose should be installed by lubricating with fresh coolant and pushing or twisting it onto its connection.

Remember, too, that the original equipment (OE) spring-type clamps currently used by most auto manufacturers are designed to apply a constant, even pressure to the hose. Most aftermarket coolant hose manufacturers have designed replacement clamps that will secure EPDM and silicone hoses to the connector without cutting or chafing the new hose. During installation, the hose also should be positioned so it doesn’t chafe against sharp metal parts or sheet metal. If OE shielding is used on a hose, it should be reinstalled or replaced with an equivalent material to protect the new hose from chafing and from exhaust heat.

When selling any modern coolant hose, always consult your cataloging for recommendations on installation and clamping requirements. It’s also important to recommend the correct coolant for topping up or flushing the cooling system. As the parts professional, you also should become the coolant hose expert. So begin your next workday by reading through your coolant hose supplier’s catalog to familiarize yourself with the product and for the special tooling required to service modern coolant hoses.

When To Sell Coolant Hoses
Since most coolant hoses are application-specific, a Vehicle Identification Number (VIN) is often required to correctly identify the engine configuration. Next, it’s important to know that most coolant hoses fail due to an invisible force called electrochemical degradation (ECD), which occurs when the hose, coolant and various metals in the engine combine to create a mild electrical current flow through the cooling system. ECD causes small cracks to form inside the hose, which allows coolant to penetrate into the fabric reinforcements.

Oil contamination also is a frequent cause of hose deterioration. Any hose should be replaced if it has suffered a long-term exposure to hot engine oil, or if the cooling system hoses have been internally exposed to oil via leaking into the radiator from an internally mounted transmission oil cooler.