I have a 91 Explorer with a 4.0L V6. The engine fan makes a lot of noise, it "roars". I have a 93 Ranger with a 4.0L V6 that does not "roar".
I have replaced the fan clutch on the Explorer with the HD unit specified for the Explorer with AC and Auto. The noise was even worse! I replaced the fan clutch with the lighter duty clutch specified for vehicles without AC which is the same unit specified for my 93 Ranger (with AC). It still makes noise. The Ranger is almost silent. I have examined the fan from the Explorer for damage and found none.
Is there some difference in the fans? Should I get a fan off a scrapyard Ranger and put it on the Explorer? The fan clutch on my Ranger is in fine shape, the engine runs cool even with AC. Is there a difference in the fan shroud?
I also have a 91 and can tell you that the roar from the fan is quite normal. In fact, if you do not hear it , then the clutch is to the point where cooling will be a problem on those extreemely hot days when idleing in traffic with the A/C on. I started to have cooling problems and changed everything imaginable, but nothing fixed it till I changed the fan clutch and got the familiar roar back I had when vehicle was new.
I kept the original fan clutch in a box as a spare. I was just wondering why my 93 with the same engine and fan clutch does not roar yet it cools fine with AC on 105F days, highway or stop/go. I guess I can swap fan and/or clutch assy's and see what happens. The roar is objectionable, and none of the other vehicles I have ever had did it except one old truck with a fixed fan.