Coolant flows into the radiator from the upper radiator hose and is pumped into the engine from the lower hose as the coolant is cooled as it travels down the radiator. Thus, hot upper and cool lower is correct condition.
Even though the fan clutch was replaced in 2000, check to see if it's hung up. If it will not turn, or has an excessive amount of viscous fluid drag, that may be your problem. If the fan is constantly engaged, it will cool the coolant down an excessive amount.
Thermostat should be a 192° unit. Did you replace the "O" ring gasket when you installed the new T-Stat? If no "O" ring gasket, then coolant is constantly bypassing the T-Stat.
2016 Ford Fusion SE (1.5L Ecoboost)
2015 Ford F-150 Lariat Supercrew (3.5L Ecoboost)
2010 Lincoln MKZ (3.5L DOHC)
2007 Ford Focus SE (2.0L DOHC) A.K.A. "Zippy"
2004 Ford Freestar Limited (4.2L OHV)
Generac 17.5KW Generator (33HP Twin Cylinder)
Farm Hand 60 Gallon Compressor (3 Cylinder)
AMSOIL in everything I own that I can get it in...
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