87MJJeep Posted July 5, 2021 Share Posted July 5, 2021 My 87 4.0L is cooling fine, but I think I have pinpointed a clacking noise to the bearing/shaft of the water pump. The four bolts holding the pulley on are tight, but if I grab the pulley, I can make it wiggle. What is the ultimate failure mode of this noise? Will the pump lock up? Or will it suddenly stop flowing? Is the pump replacement straight forward? Is there a good reference write up for it? Is there anything to look for in the replacement pump? (I'm an old school Pontiac guy, and the impeller gap on those is critical for proper cooling. Many replacement pumps have a gap that results in barely adequate cooling.) Thank you. Link to comment Share on other sites More sharing options...
jdog Posted July 6, 2021 Share Posted July 6, 2021 42 minutes ago, 87MJJeep said: is the pump replacement straight forward? Is there a good reference write up for it? Is there anything to look for in the replacement pump? (I'm an old school Pontiac guy, and the impeller gap on those is critical for proper cooling. Many replacement pumps have a gap that results in barely adequate cooling.) yeah its pretty straight forward, as for stuff to look out for, belt tension. thats the killer of these pumps. Link to comment Share on other sites More sharing options...
87MJJeep Posted July 6, 2021 Author Share Posted July 6, 2021 yeah its pretty straight forward, as for stuff to look out for, belt tension. thats the killer of these pumps.Thank you for the tip. I replaced the alternator a few years ago. That's the only time I have messed with the belt. I don't even recall how it was tensioned. Sent from my SM-N975U using Tapatalk Link to comment Share on other sites More sharing options...
jdog Posted July 6, 2021 Share Posted July 6, 2021 it gets tensioned by the ps pump bolt, very easy to over tighten Link to comment Share on other sites More sharing options...
87MJJeep Posted July 6, 2021 Author Share Posted July 6, 2021 it gets tensioned by the ps pump bolt, very easy to over tightenThank you! I will be very careful when I put the new water pump on. Sent from my SM-N975U using Tapatalk Link to comment Share on other sites More sharing options...
scaleless Posted July 6, 2021 Share Posted July 6, 2021 https://www.amazon.com/dp/B000CRDLZM/ Link to comment Share on other sites More sharing options...
87MJJeep Posted July 6, 2021 Author Share Posted July 6, 2021 https://www.amazon.com/dp/B000CRDLZM/Thank you. I never would have thought to look for such a tool. Sent from my SM-N975U using Tapatalk Link to comment Share on other sites More sharing options...
AZJeff Posted July 6, 2021 Share Posted July 6, 2021 2 hours ago, jdog said: it gets tensioned by the ps pump bolt, very easy to over tighten Most guys, when they first own an MJ/XJ with a 4.0, GROSSLY underestimate the amount of tension needed to avoid belt squeal on that belt setup. If you spend any time with these engines, a belt tension gauge is very useful. Lacking that, you can use the “approach to zero” method. this is where you tension the belt to what you think is “pretty tight, but maybe not quite there“. Then you drive the vehicle and load the belt by making sure the AC is on. If it squeals, bet out and add a SMALL AMOUNT more tension. Then drive it again. Repeat this process until the squeal is gone. My engine currently will squeal for about one second when I first kick the AC compressor on when it’s cold. Once it’s hot, the belt is stickier, and no squeal. That’s about perfect….tight enough, but it’s not going to trash alternator or water pump bearings. Link to comment Share on other sites More sharing options...
87MJJeep Posted July 6, 2021 Author Share Posted July 6, 2021 Most guys, when they first own an MJ/XJ with a 4.0, GROSSLY underestimate the amount of tension needed to avoid belt squeal on that belt setup. If you spend any time with these engines, a belt tension gauge is very useful. Lacking that, you can use the “approach to zero” method. this is where you tension the belt to what you think is “pretty tight, but maybe not quite there“. Then you drive the vehicle and load the belt by making sure the AC is on. If it squeals, bet out and add a SMALL AMOUNT more tension. Then drive it again. Repeat this process until the squeal is gone. My engine currently will squeal for about one second when I first kick the AC compressor on when it’s cold. Once it’s hot, the belt is stickier, and no squeal. That’s about perfect….tight enough, but it’s not going to trash alternator or water pump bearings.That is great to know! Sent from my SM-N975U using Tapatalk Link to comment Share on other sites More sharing options...
cruiser54 Posted July 6, 2021 Share Posted July 6, 2021 This might help. Link to comment Share on other sites More sharing options...
87MJJeep Posted July 6, 2021 Author Share Posted July 6, 2021 This might help. Thank you, Cruiser! Sent from my SM-N975U using Tapatalk Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now