That could be the reason why. I know that the install goes how the hoses are angled. I also wonder if that can installed the other way almost the the inline mod and pug the other side. Would that be possible?

 

I agree and it's installed just as you explained but the fact that the flow is weak through the heater core at idle is driving me crazy and it's not because of air in the system. I've bled the system and it's good. Didn't have a problem before the teardown so just suspect something is routed wrong or blocked. I'm thinking the issue may just be the Tstat itself.

 

With Land Rover closed loop setup , coolant circulates constantly trough heater core & around engine, it's a closed loop, & it goes trough radiator when
T-stat opens,, so even if T-stat doesn't work you should have circulation in engine & heater core all time & it will actually make coolant very hot & you will have lots of heat, insted of no heat,,,
So if you don't have heat from heater core it has nothing to do with T-stat itself,
It's either air in heater core or coolant doesn't circulate for some other reason,
But that will make engine overheat very quickly,

(Correction: T-stat can cause problem & not let heater get hot, but only way it can happen is if
T-stat is stuck in open position & coolant circulates trough radiator constantly)