Erratic cooling

93 S60 12.7 During cool weather the radiator keeps up with cooling the engine. Now at 85 degrees ambient temperature the radiator won't keep the engine cool without running the fan all the time. I have run a cleaner through the cooling system. It seems to have helped a little. When the engine is wanting to run warm, taking my foot out of it and rolling down hill the temp. won't drop as quickly as it should. Late in the day Monday evening the temp. went right back to climbing slowly while going up hill and dropping quickly after topping a hill. Long story short, sometimes the cooling system is very effective and some times it won't get the job done. After this all started I changed the water pump and then the thermostats. The old stats I put on the stove tonight and they seem to be working fine. It is as if something is slowly the flow of coolant at times. I checked the radiator and it was 180 at the top and 144 at the bottom with the fan on. Any suggestions would be greatly appreciated.

 

I disassembled the cooling package a while back. When I got it clean I put a screen in front. Too dang many bugs, love bugs and cotton seed dust down here. I did quit the cotton seed hauling though.

Not pushing coolant.

How would air get in the cooling system.? No air controlled heater valves.

I can watch the temp. gauge and see the stats open and close by the temperature changes. Other times not so much.

This has been going on for some time w/o any other issues.

 

Senior moment last night. The air compressor as a way of getting air into the cooling system. It hit me at 3am this morning.

This morning: 54 degrees outside and I could watch the stats opening and closing. Loading now so I shall see what happens.

The vent line has been checked and it is running coolant through it ok.