From Gates Australia

All types of vehicles have a cooling system and these systems no longer just keep the engine/motors cool; they also cool and warm various components under the hood, as well as other areas of the vehicle.
In order to convey coolant to these components, the “radiator hoses”, as they were once called, have become much more complicated and even contain assorted elements built into the hose to perform a wide variety of tasks.
These hose assemblies are called “modular” coolant hoses, because they employ a variety of modules in their construction.
A modular hose is defined as a coolant hose assembly, with one or more modules (which are built into the hose) and has coolant flowing through the module(s). These modules can be a branching tee in the hose, quick-connect, valve, drain, air-bleeder or sensors.
You will primarily see modular hoses on European vehicles, but the Asian makes are quickly following suit as modular hoses simplify the plumbing of the vehicle at assembly. One hose assembly will connect to multiple components.
These modules within the hoses are critical to the proper operation of the cooling system. For example, some hoses include flow-restrictors within the hose. These restrictors reduce the flow and pressure within the hose to certain components such as the heater core; and are required to maintain core integrity.
Last year, Gates says it received a call from a consumer regarding the repeated failure of a heater core in a limousine. It seems the limo had a leaking modular hose and a workshop replaced it with a new, (standard) hose. Soon after, the heater core started leaking. The heater core was replaced, and after just a few months, it started leaking again.
Once the consumer finished explaining the situation, they were asked by Gates if the replacement hose included a flow-restrictor; it did not. Without the restrictor, system pressure was simply too high for the core. When replaced with a Gates modular hose, Gates report that the issue went away.
Modular hoses can be significantly more costly than standard, moulded coolant hoses. In general, a modular hose is likely to be three times the cost of a standard hose. Some light trucks utilise modular hoses that can have an OE dealer cost in the $500+ range.
Often, such hoses include multiple branches and connectors, with smaller I.D. heater-type hoses which snake around inside the engine compartment. Gates explains that Modular hoses are not a dealer only item, stating you can find the same Gates aftermarket hose from a reseller for significantly less; saving your customer substantially and making it more profitable for you.

For more information on the Gates modular hose range, go to