I am getting my 90 240 wagon ready for the wife, so as you all can imagine, this baby needs to be super reliable, or else...many nights of cold shoulder.

My concern is the heater hose, there are two of them. One goes from head to the wall, and the other one goes behind the head along the wall.

I squeezed them, and one of them is pretty soft, so probably its time is due.

My question is what's involved here? It seems that I need to remove the intake manifold to get the head end. Should I replace the temp sensor and injector seal? (they are fine, though parts are pretty cheap)

The hose that runs along the wall is wrapped with this insulation stuff, why so? Should I replace both of them?

Is the heater core directly on the other side of the wall?

How hard is it to change the heater control valve? Should I replace some more hoses in there?