Does anyone have, or know where to get, the "correct" heater hose for the Amphicar? The correct size is 15mm ID, 24mm OD oil resistant hose. Hugh has been out of it for awhile and unfortunately the stuff in the car I'm working on was cracked near the engine so I figured I'd replace it but I've had trouble finding the exact stuff. I'm not a fan of using regular 5/8" hose since I've been told it won't survive laying in an oily bilge and it's not exactly correct anyway.
I use a special very expensive hose, a roll cost me about $175.00 and will do about 1 1/2 cars, I am going threw my papers now and if I find the bill I will post the product, it is very strong(Stiff)it is 5/8,,i/d. which means its a little bigger but have not had any problems.
Also when you lay it along the floor I put it in that heat retaining foam to keep it up off the floor, it also will act as a insulator to keep heat in hose as up in colder climates we need all the heat we can get to defrost those windows, hey even in a rain storm in Boston we need more than we could get! and I do not put the mid drain fitting back in(just another place to leak.)Im talking about the one between front and rear seat, this was put there to drain the system, not to bleed it,bleed system at front near heater core, there is a special key to do this with.There is also a line bleed on top off the valve cover to purge coolant as you fill rad.I have done this to all my Amphis since 1995 and all is well. Original clamps will not fit as it is too thick.
I bought some heavy duty 5/8" ID hose at NAPA which is much thicker (bigger round) than the regular junk they sell, plus it is reinforced with a fiberglass strand. Not cheap and typically it is on the back shelf somewhere. 5 years to date and zero issues.
I use the heavy duty (thick wall) 5/8" hose which has been in my personal car for 10 years now w/o problems (soft or cracks). I wouldn't add any insulating wrap to it because you don't want to retain the heat unless you use your heater for heating. If she gets too warm, I pull the heat knob to allow the water to circulate thru the heater core to drop the engine temp. This works well especially if you have some water in the bilge to draw that heat out. I also wouldn't take out that bleed valve as it is there for a reason, to bleed out air in the system (one of the 3 places to bleed air from the cooling system) which is probably the #1 reason most cars overheat anyway. There are no leaks if you use good clamps and the valve is maintained and clean.