Firstfives.org

My '79 528iA was running pretty warmly on the highway. It has a new thermostat, so I deduced it was the radiator. I had it re-cored and installed it this weekend. I filled it up with coolant, bled it and took it for a drive. The damn thing still runs hot! It's just below the 3/4 mark on the temp gauge.

Could it be that the thermostat is a faulty one? The lower radiator hose gets pretty damn hot - at least comparable to the upper hose. I don't know where else to look.

fan clutch?

Fan clutch is brand new. It doesn't really overheat at idle, only when driving.

Water pump?

Check for leaks even with new hoses. I would then look at the radiator.

No leaks, new water pump.

The radiator was just re-cored and it was tested before I took it back from the shop.

Remove the thermostat see where your temp is you might get an infrared temp sensor tool and check the temp at the hoses and radiator could be your gauge is inaccurate. Otherwise I might suspect a small crack in the head any white smoke? I would think normal running temp should be 195 F to 205 F.