Thermostatic Clutch Fan Operation

[cleszkie]

I recently replaced the unclutched fan (steel fan with spacer) with the stock 6 blade steel fan and a new thermostatic clutch (Hayes unit) on my 72 4WD K5 Blazer (350/350/205). I have noticed that my water temperature will get in the 200 to 210 degree range, and the clutch is not engaged (I stop truck, jump out and spin the fan). I thought the problem was with the clutch, so I replaced it and still have the same issue. Should the fan clutch be locking up to give me more RPMs and more air flow at that temperature? Do I have the correct fan clutch? On 4WD models, the fan clutch is quite a distance from the radiator fins, so I was wondering if the 4WD models require a clutch that locks up at a lower air temperature than say one that was for a 2WD model.

I have a new 4-core brass/copper radiator, a good fitting stock shroud, relatively new water pump, good 180 degree thermostat, and a new water temperature sending unit and gage (with temp sending unit between the 1 and 3 cylinders on the block on the drivers side). Any help or advice is greatly appreciated. Thanks in advance.