Strange sound from front of engine.

[brewdude]

My Bronco started making a strange sound. When my truck is idleing there is a thump thump thump sound comming from the front of the engine. I only notice it when at idle. It sounds like it is coming from the alternator but could be comming from the water pump. Would either of those make that kind of sound when they are going bad? In my past experiances those parts just failed with no warning. TIA

 

[BRONCO26]

What I Would Do Is Take All Your Belts Off One At A Time Until The Noise Stops. Hopefully It Is Not Your Engine.don't Run The Engine Long If You Have All The Belts Off.

 

[brewdude]

Thanks I'll give it a try. If it is the engine I guess I know where my tax refund is going, a new 351W ;D

 

[trailpsycho]

Make sure your fan shroud isnt loose. Had that happen before too...they get brittle and start breaking at around 25 yrs old....

 

[broncnaz]

Could be the fuel pump I noticed my 71 making a similar thumping sound and after listening real close I'm pretty sure its the fuel pump which reminds me I need to change it out one of these days as it also has started to leak.

 

[Naildriver111]

I vote fuel pump too, I swapped to an electric fuel pump and thought I could just leave the old mechanical one on the engine. Wrong! that thumping sound had me stumped for a couple of days, then I figured out where it was coming from.