(At a -15 deg C (5 deg F) outside temperature) I notice that the fan roars excessively, sometimes after 10-15 minutes in my 97 GMC Sonoma. I understand, and I usually get the fan roar at start as usual, it seems that the fan clutch is a little lazy, not wanting to disengage at ~70 to 80 deg C(160 deg F). When I rev the motor slowly with the throttle body, it starts blowing a frenzy, and doesn't let the fan slip until the RPMS get to ~2300RPM, when I rev hard, the fan slips near immediately. I checked for oil splash/leaks from the fan clutch and it looks pretty clean. I noticed the fan clutch on my 01 Dodge Dakota is much looser than my GMC Sonoma after a long drive, the GMC actually feels the same before and after a drive, I haven't checked the Dakota at a cold start. The truck takes a bit longer to warm up now too, I'm not sure if it's the thermostat starting to fail open or the fan blowing too much air.
Does this sound like a fan clutch problem? In sub-zero winter weather the fan doesn't have much incentive to blow hard, so I figure the clutch should thermally disengage after the fluid drains back to the resevoir after startup, is this correct?
Check my theory, at high temperature radiator air flow, the fan engages, and when the air temperature from the radiator drops, the fan disengages, am I wrong? So using this theory the fan SHOULD NOT engage after a couple of minutes in the winter right ?
Anyways, it roars quite a bit past idle up towards 1700 to 2200 RPM, my gas mileage has gone down the tubes recently(it was 16-18 US-mpg, or
19.25-21.7 Imp-mpg) and is now around 11 US-mpg or 13.2 Imp-mpg. Even in the winter my mileage has never changed this drastically. The exhaust smells normal, not rich at all.