Quote:
Originally Posted by DifferentPointofView
Red, I have no Idea about the fan clutch (specify more please?) , but the radiator fan seems to run all the time.
Red, I think that might be one of the things to why it never overheated, cause I've noticed the fan can INDEED probably blow a cat down the street.
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np, standard cooling setup on ZJs with the 4.0 is a mechanical fan driven by a thermo-viscous clutch bolted to the water pump. Basically an engine driven fan with a clutch that can sorta turn the fan on and off depending how hot the air is that is flowing across it. A mechanical fan runs so long as the engine is spinning, the only thing that varies is how fast its spinning and how much torque is being applied to it, which is what the clutch does. A thermo-viscous clutch is a thing kinda works like a torque converter. You have two plates with a fluid between them. If its cold, the fluid thins out, letting the plates slip, allowing the fan to run slower, if its hot, the fluid thickens, forcing the two plates to match in speed. Now since the clutch is directly hooked up to the water pump, the more "locked up" the clutch get, the faster the fan must spin, the more power it takes to spool up the 15lbs of the fan and the mass of air it moves, to whatever your current RPM is.
So, using your grill block you are warming up the engine compartment, possibly heating up the fan clutch and making it prematurely lock up, which adds load on the engine, which drops your FE. You could be getting better numbers if it wasn't spooling up.
Far as I know your ZJ didn't come with a supplemental e-fan, the WJs did, which was what I was getting confused about. Else I was figuring you could just unbolt the fan and clutch assembly and just run around with the e-fan and see how well it can manage temps.
Other alternative is to do an e-fan swap using either the setup from a 5.9 ZJ or the usual Ford Taurus swap.
The fan is cool though. Makes a rather unique sound and one hell of a mess if you are driving over dry dirt.
That and its hard to kill.