Cant test, as it will only o/heat during race conditions.
I have fitted an electric water pump, but have now decided that I might not need it.
After lots of phone calls and sleepless nights...wondering how something so simple can be so hard to fix, I have come to the following conclusion.
Subaru has had a design fault in most of their engines. I now think that the engine itself is not overheating, only cylinders 4 & 6 (which happens to be where my temp sensors are located). Due to the design of the water crossover outlet, water cannot pass freely from the right side of the engine (looking front of engine). This could be the reason for many subaru engines (4 & 6 cyl) blowing #4 or 6 headgasket, and some splitting bores!
The H6 3.0ltr engine actually has 2 outlet to the radiator from both sides of the block, probably to overcome this.
Also, thanks to 260, we know that coolant passes from the waterpump into the lower half of the block, and can only get to the upper half by passing through small ports in the heads...so if these ports block it will restrict flow to the outlets also (who ever said scoobies were good engines?)
I will be looking at replicating the H6 option, and when I get the RH rear cylinders relatively cooler, I will move my temp sensors to a position where a more average temp will be read.
Milbrodale, here I come!