Relocating LT heater coolant valve where?

...so in advance of the radiator coming out for repairs I thought to take the opportunity to relocate the dreaded coolant valve associated with the heater circuit. For one day it will not work and I don't want to take the rad out just for that.

Any help here such as where to relocate it and any gotchas is much appreciated.

Cheers!
Dave

A common mod on LT's is to delve a bit deeper into the heater problems caused by a dumb design and prevent future leakages that are pretty much inaccessible.
This involves removing the actual heater core from the heater box so will involve removing tjhe centre poertion of the dash and console to access.
Oka in their wisdom have the heater core connections INSIDE the actual box so when they leak (which they all do as time takes it's toll) this mod will solve the problem as you will be able to reroute the heater hoses and remove over a metre of hose from the circuit.
Once you have removed the centre console section you will be able to see the black plastic top section of the HVAC system with the ducting hoses coming off to the vents.
Remove the hoses off the plastic section and then remove the plastic piece held on with small self tappers sort of at the corners.
Once you have that out of the way there is a flat sheet on the top with a flapper in it, remove the front screws holding it down and lever it up enough to see the heater core and connection pipes, the clamps of which are impossible to undo in the box and which often leak. They obviously fitted the hoses and then slid the heater core into place.
Remove the heater core, easier to cut the hoses off inside the radiator air duct.
Get your radiator guy to flush and clean the heater core and while he's at it flip the in and out connections approximately 180 degrees (you will need to check this before getting it doen to get the corrct angle)
As you can see there is aslot in the box on the RHS and you need to make the heater connections come out on the passengers side and face virtually horizontal back towards the back edge of the duct underneath. In that position there are two blanking plugs where your heater hoses will come through from the engine bay above the air duct.
Once you have done all that a new heater tap can be installed up in the engine bay in the hose.
you may have to adjust or replace the heater tap cable as it may be the wrong length depending on where the tap ends up. I took the easy way and just put a cable in the ashtray recess that can be pulled up and down as required.
The heater core is from a Torana if you need a new one.

Thanks for your depressingly thorough project description Peter! I hate that bloody area...

For the time being I want to leave everything in the centre box as-is. Partly because it works and mainly because I just got through taking it apart to run electrics and other stuff in there....Kelvin Marquand cleaned out the heater core when he did the engine work anyways.....so if the short term is an opportunistic 'move the heater valve' how would I do that whilst leaving the rest in situ?

Dave the problem is that the heater hoses are in the radiator air duct and you have a big fan turning at the back so you have to get the hoses in and out of the duct without getting anywhere near the fan.
There is also too much hose in use in standard form, the Fx@#wit that decided the cooling duct was a good place to run hoses and place the tap in was a good idea needs sorting.
I also looked long and hard at the accelerator cable placement, another "brainwave" from the design team which means radiator out unless you cut nd access hole in the tunnel

Thanks again Peter. I'm strongly leaning towards using an electrically controlled heater valve to at least get rid of the operating cable limitations. Will need to get my head in there one the rad is out and see what the options are.

I think a few others have gone the electrically operated valve route.
One thing to remember is that the cable from the heater/temperature control lever on the dash doesn't connect directly to the heater tap.
The cable connected to the lever goes to the drivers side of the heater box and operates an gimbal mounted on an arm that opens the heater core to the airflow inside the HVAC unit, a second cable goes from the gimbal to the heater tap in the radiator duct.
So when you move the heater tap or replace it with an electric tap, as well as operating the new tap either electrically or directly by its own cable you still have to adjust the temperature lever on the dash to open the airflow to the heater core.
For some reason ever since fitting the 6BT the heater never gets hot enough so I just don't use it at all and fitted a 2kw diesel air heater up under the glovebox which just werks well and makes the Oka heater obsolete.

So, your post explains everything! Now I have the oem heater valve bypassed and, as you mentioned, the position of the heater arm does still select hot or cold air when fan is on. I have bought an on/off electric solenoid valve to fit somewhere convenient. So that now I have 2 things to do (a) switch on heater solenoid then (b) vary the heater control arm and fan. Phew!