focusbob2

Hi Guys,
The coolant return line from the rear of the block on my 1999 1.6 silvertop has a small black restrictor valve fitted. The only time I would see coolant returning to the expansion tank was when the thermostat was fully open and the coolant hot.
In order to bleed air from the system I removed the restrictor from the hose and got plenty of air going back the expansion tank. Now I have a constant coolant feed back to the resevoir hot or cold.
Does this device restrict coolant going back to the reservoir, therefore helping to increase coolant flow/pressure around the block during warm up?
My wife travels 15 miles on motorway and a little side roads, the CHT sensor reads 90c , so the thermostat is not quite fully open , hence the air bleeding. The car never overheats, has had a new water pump/ thermostat but when the air con is used, the bottom hose is overwhelmed and cools down.
Any ideas would be gratefully received
Bob.