Hello,
I am putting a 2001 Montero Limited back together. The heater lines to the front and rear heater core are rusted out and unusable. My question is the routing of the lines from the engine inlet and outlet to the heater cores. I have looked at Alldata and Identifix but can find a routing diagram. Can I run from the engine outlet to the heater core and straight back to the engine inlet or do I need to put in a bypass loop in so coolant will return to the engine when the heater is off? I hope I explained this correctly. I plan to use 5/8" silicone heater hose in place of the rusted out hard lines.
Thanks,

 

You probably want to run the lines as they are right now - through the bypass loop. That way the coolant (heating fluid) will circulate and not sit unused, accumulating deposits if rear heater is not run all the time (or during summer).

 

Thanks, that was what I was thinking.