RPM based "Noise" question

[bdp1978]

I know, I know, diagnosing "Noise" over the internet isnt exactly a preffered method.



So fella's, my truck has developed a noise from 2300-2600 RPM. The noise comes and go's and is pretty faint but is becoming more frequent, I only hear it when the radio is off.

The noise sounds almost like the noise you would get from 2 plastic gears slipping on each other and is coming from somewhere in the front of the truck. As soon as the truck shifts and drops RPMS the noise goes away.

Any ideas or anybody have anything similar? I'm thinking along the lines of the idler pulley/ fan issues but not sure and it's hard to diagnose due to the small range it happens at. I looked under the hood and everything seems tight and there is no evidence that the fan is contacting the shroud so I'm a little stumped.

[dirty anton]

also check your belt tensioner pulley,just replaced mine. i could sometimes hear the sound your describing while driving but more often when i first started the truck. if you cant exactly pinpoint the noise and start replacing things you may want to first start with this and the idler pulley, and if you strike out at least it only sets you back 40 dollars for parts your gonna have to replace sooner than later anyway.(at advance auto) i have replaced my fan clutch twice but it was a ticking noise for several months before the infamous supercharged vacuum cleaner syndrome! hope it helps

[djthumper]

Get a mechanics stethoscope and probe around in the area you think it is. It will help greatly in finding the problem. I know Harbor Freight has them for about $3 or so.

[bdp1978]

I'll check into the belt tensioner pulley and am planning on doing the idler pulley this weekend.

The fan clutch is still on hold even though I do have the "Supercharger" going on right now.


I've got a mechanics stethescope that will be getting used this weekend. My buddy is bringing over his TB for us to tear into the 4 wheel drive system so it's looking like a TB wrenching wknd. Which may be mines last, I'm getting pretty close to saying goodbye to the old girl in lieu of a new 1500 Sierra.