I am about to replace the cooling fan on my '94 4.0 Ranger for the third time. I needed to do the lower intake gasket 4 years ago @ 54k miles and the fan had several cracks so I replaced it.
Checking it again and it is cracked in several places again after 4 years and only 3000 miles. The last fan was made by Dorman.
Is this a common problem?
-greg

 

Yes, it seems to be a very common problem, but I have yet to hear of a case where the fan actually came apart. It's happened to both of the 4.0 liter engines I've worked on; multiple cracks around the perimeter of the hub. I also see it a lot on engines in the salvage yard.

If you're really concerned, you might consider installing an electric fan in place of the stock mechanical fan.