M42 radiator

I just installed a new radiator into the latest vehicle to join the fleet and had an interesting observation. After getting the radiator installed and purging the air from the system I took the car out for a drive and the temp needle stayed right in the middle as it should as I installed a 92 degree thermostat. When I got back to the shop I inspected for any leaks and all was fine. Out of curiosity I felt the upper radiator hose and it was quite warm. Felt the lower radiator hose and it was cold as a clam. The radiator fins were also hot on the upper half while the fins were cold on the lower half. I thought this to be strange, but maybe not. Do I still have air in the system or is this normal for the radiator to be both hot and cold at the same time. The heater worked great too. Also the outside temp was about 40 deg F!

That sounds like the radiator is doing its job of dissipating heat from the coolant to the air. Hot goes in at the top, cool comes out at the bottom and then goes to the engine. If it was hot at the bottom, it wouldn't be very effective at cooling the engine!

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Dave
'91 325iX