Engine Cooling problem
1999 Ford Taurus 6 cyl Front Wheel Drive Automatic 89000 miles

Need to replace the metal heater hose assembly. Two questions...

Most importantly... how does the by-pass in the heater hose assembly work? Does the metal piping have a release valve built into it that automatically opens when backpressure increases due to heater core getting clogged? Or, is it simply a smaller diameter line in the by-pass than the one that goes to the core, forcing coolant through the core by "path of least resistance" concept ?

The hose assembly is incredulously wrapped around a long black plastic tube that run vertically just adjacent to the corner by the driver's side firewall, resembles an extension on a leaf blower, and is open on the end. I cant figure out how to get the assembly our without removing that tube (horn, possibly?). Thoughts?

I appreciate the info!