Harv...
As I stated, my pump doesn't pump out of the top hose at idle, so you may have a point there. Bit expensive to swap out at over $100 just to eliminate the pump, unfortunately, but a bit cheaper than Ken's suggestion of a head gasket/cracked head.
Might have to bite the bullet and buy a "spare".
a) I bought and installed a 71ºC thermostat which I have in at the moment. I took the last one out when it boiled and ran home with no thermostat - no difference.
b) Both tested and work OK.
c) See "a" above
d) I installed new radiator hoses and the bottom one has a wire coil inside to prevent collapse.
e) New fan belt fitted and double checked for tension
f) Brand new (recored) heavy duty radiator in it now - perfectly clean and smells of fresh paint - no difference
g) Checked cap for recovery version, which it is not. Bought new one when it first boiled and got yet another new one with recored radiator - still no difference.
Thanks for your help Harv, it is appreciated.
Cheers
Joe
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Ken (mcl1959)...
The water pump has a cast type impellor, but I notice the cutouts/fins in it are deeper on the fan side of the pump as opposed to the shallow ones on the engine side. I would question whether the impellor was correctly fitted to the pump except for the fact it worked well for nine months, and I have only just had this overheating problem in the last two weeks.
As for the head gasket or cracked head, well maybe, but as you say it usually happens after overheating but not before. I'll have to do a compression test and maybe talk to a mechanic to see if I can test the head theory before I pull it off. Then again I may as well change the gasket anyway. I can't go on like this.
Thanks for your help Ken. All ideas are taken on board and at the very least they help me feel I am not missing something obvious.
Cheers
Joe