1993 4.0 Odd sound

[runnhrd]

A while back had the water pump replaced and daughter drives the truck. I drove last weekend and there was a distinctive sound like a vent door closing or something along that line bumping sound when driving with the heat on. She tells me "Oh Dad that started right after the water pump was replaced" yep that was six months ago so been going on for a while. I checked and when running I could hear a pounding sound coming from the firewall and when the hood was open near the radiator. I will presume it has something to do with the water pump that was installed. I did open up the system to ensure there were no air areas left that had not been bled out. Any help appreciated! Truck currently has 298k on the ticker and running like a top besides this bumping sound.

 

[rusty ol ranger]

Loose/misaligned/cross threaded fan/fan clutch?

 

[adsm08]

Loose/misaligned/cross threaded fan/fan clutch?

Doubt it. Fan clutches use fine threads so they are hard to cross. They also don't come loose often, if ever. They are designed so that the action of the pump spinning tightens the nut.

I don't even tighten mine anymore. I just spin them in until the nut stops moving. I have never had one come loose on me, and I always need the wrench to undo them again.

 

[Denisefwd93]

Loose idler? They usually squeal though 6 months... in my experience.. they don't fix themselves.

 

[rusty ol ranger]

Doubt it. Fan clutches use fine threads so they are hard to cross. They also don't come loose often, if ever. They are designed so that the action of the pump spinning tightens the nut.

I don't even tighten mine anymore. I just spin them in until the nut stops moving. I have never had one come loose on me, and I always need the wrench to undo them again.

Oh yeah, makes sense. I forgot about the way the newer style ones thread on. Last one i did was on my 77 and it just bolts on to the water pump with 4 bolts and the fan bolts to the clutch.

 

[runnhrd]

Well so far all the items you have mentioned have already been ruled out. Thanks and will keep hunting.