91 Turbo Cooling Issues

[a400tool]

My 91 Turbo (manual) has a cooling issue. When driving, temp is within normal limits, slightly less than half way between H and C. When I stop driving, the temp increases to 3/4 hot. A fair amount of cooling fluid is then passed to the expansion tank and onto the ground. After the engine cools, there is no fluid in the expansion tank and the radiator is not completely full. I have changed the thermostat and seal, upper and lower radiator hoses, the radiator cap and the fan clutch. The water pump is working, no leaks or bearing play. The radiator was replaced several years ago and appears to be in good nick.

Any ideas would be greatly appreciated before I change/upgrade the radiator and water pump.

Car is a daily driver (102k mi), no mods. Head gasket has been changed and compression on all six cylinders is within spec. No evidence of water in the engine oil.

Thanks