the POLYETHELENE hose melted....
the HIH is about 20 feet total lenght. the "return" heater hose has a fuel line as well. I used a "Y" adapter for the fuel supply line and ran parallel HIH fuel supply lines from the tank to the engine. One HIH line starts at the engine and goes back to the tank, & the other HIH line returns the coolant back to the water pump. That way I didn't "waste" the coolant returning to the engine and doubled my fuel heating. Each fuel line should flow 1/2 as fast but absorb twice the heat.
anyway....
I pulled the HIH assembly apart last night...the poly hose as the coolant inlet was total melted. It had gotten so hot that as it melted, the suction from the lift pump collapsed the poly hose and it began to get sucked into the brass hose barb it was attached too. This had the effect of mostly blocking that side of the parallel fuel lines and preventing even more water from getting into the fuel. Thus I was able to drive for about 2 days with the HIH system before the water level in the fuel reached critical levels and shut the engine down.
The return HIH hose obviously is not as hot as the supply one. The poly hose in that one was noticably discolored from the heat, but had not failed...yet. So it was supplying all the fuel after failure and the melted side was trickling in water.
I'll try to post some pictures tomorrow.
It was ugly.
I drained the tank and will be flushing it with RUG today and then let it dry out.
I'll be rebuilding my HIH, but with copper or something else.