Yep, been tinkering with the V6 again
The car would take ages to warm up, even zooming down the motorway at 10mph (my speedo still isn't fixed).
When it eventually reached 90ºC or above (the fan kicks in just below 100ºC
), it wouldn't cool down, eventually after about 15 miles at constant speed on the motorway, the temp would drop to about 70ºC.
I thought the stat is obviously stuck open when cold, but not opening enough when hot.
Took the stat off when cold and yes, it wasn't fully closed. Dropped it into a pot of boiling water and it didn't open any further. I think the car sitting for so long had allowed crud to build up.
Anyway, some release spray and then blasting with a blow torch for about 5 mins, the rod started to move and open the stat, could see a line of crud on the rod so out came mr emery board.
Once rubbed, I dropped the stat into cold water and it shut properly.
Stuck it in hot water again and it opened slowly
Put it back on, car warmed to 80ºC at idle in about 5-6 mins, eventually it reached 90ºC, then the fan kicked in and the temp dropped nicely. The heater works properly aswell now.
Need to take the car on a drive to check it properly, but I think I may have saved myself £25 !!!!