When outside of my truck while it is idling I can hear some sort of noise which I can best compare it to a rhythmic strain about every two or three seconds. Could this be the brushed in the alternator, power steering pump or something else. Has anybody heard a similar noise?

2000 Disco 136000mi.

 

I could be several things. I would pop the hood, purchase a auto stethoscope and try to narrow down where it is coming from. Could be worn out bearings in the alternator, power steering pump or idler pulley or a bad tensioner. What condition is the belt in? Does it look shiny? Your just going to have to narrow it down a bit closer and get back to us.

 

DITTO!!!

 

Idle rpm range???

Noticed this morning while warming my truck up that if I ever so slightly bump up the rpm's the straining noise appears to go away (or at least not noticable). Under idle my tach reads around 500 or so, I bumped it to around 700-750 and seemed to run smooth. Is 500 rpm at idle to low?

 

500 is too low for sure, but to start listen to the suggestions so far. Pull the belt off the tensioner and check that everything spins freely and without any grinding noises. I've added 'grease idler and tensioner pulley bearings' to my service schedule now though since I had both go out at the same time after some deeper water crossings.

 

You really need to quit play with the factorys preset idle and do as we have asked and get under the hood and listen where the noise is coming from.

 

I plan on pin pointing noise when I get home today

I only noticed the change in idle rpm's by lightly pressing the accelerator pedal, not messing with the idle preset.

 

I misunder stood, let us know what you find.

 

was able to locate what I think the source is, sounds like it coming from the tensioner pulley. Obviuosly it needs replaced, is that a normal sound when they begin to go out?

 

Yes. Sounds like the bearing is shot.