Jeep 4.0 water pump failure question


Long Jeep Fan
Holladay, Utah
I posted in the "what you worked on thread" about the brand new water pump on my daughter's Jeep that self destructed. I pulled the pump out this afternoon and the water pump impeller shaft had moved about 1/4 inch out from the factory position grinding the stainless steel impeller against the aluminum inner pump housing. I have worked on Jeep 4.0 engines for over 30 years and have replaced many of these pumps. I have never seen a 4.0 water pump do this. I have the pump going back for a warranty refund but wondered if anyone else has ever seen a 4.0 water pump walk the impeller out out like this one did. I've seen the pumps go the other direction and rub on the number one cylinder right behind the pump but not the other direction. I was glad to see that the pump hadn't hit the block but I will still have to flush the entire cooling system out to remove the aluminum flakes.


Active Member
Definitely sounds like this jeep is cursed with the issues you have been having. I have had 4 or 5 (maybe 8) 4.0 powered vehicles with multiple water pump swaps and never had either issues you've described. You're just lucky i guess.