‘Chevrolet Forum’ Helps Member Diagnose Strange Whistling Noise
We’ve seen many mystery problems solved at Chevrolet Forum, no matter how hard they are to track down.
We certainly love our old trucks around these parts. But like any true love, they aren’t perfect by any means. Over time, you’re bound to deal with broken/worn parts, and worst of all, strange noises. These sounds can be rather frustrating to diagnose, as any particular noise can signal a problem in a number of areas. But that’s why places like Chevrolet Forum exist. And it was there that member davidt443 went to seek help when his big Chevrolet diesel started making a strange noise recently.
“I have a 2000 K3500 with the 7.4-liter Vortec engine. Recently, when starting the truck, I would get a very high pitch whistle noise off and on only for a few seconds when it’s cold out. I’ve noticed this noise only happens when it is under 60 degrees. The noise it is so loud that it is hard to pinpoint where it is coming from. And after about 3 minutes, it will go away and won’t come back until the engine is fully cold and started back up. Anyone else ever experience this?”
Since the noise doesn’t change when the motor is revved, we can rule out a problem with a belt. So Renucleus suggests a method the OP can use to track down the source of the noise.
“You can use a piece of heater hose as a stethoscope and carefully place it on each component (pulley, a/c, alternator) to find where the sound is the loudest. Just be careful with the hose around moving belts & pulleys.”
After a little digging, the OP narrows down the root of his whistling noise.
“I am thinking it is an idler pulley and will change that out today. Hoping its not the alternator or A/C compressor bearings. I will put in a new serpentine belt as well.”
Thankfully, that doesn’t turn out to be the case.
“I have confirmed the idler pulley bearing was bad. Only $25 later and a new serpentine belt and the old 7.4 purrs like a kitten with no noises.”
It’s always great to see folks solve these types of problems using Chevrolet Forum, and this appears to be another open and shut case. So if you find yourself driving around in your old Chevrolet pickup (or car) and experiencing any sort of problem, head over here and post it up to receive some free expert advice. And if you haven’t already signed up to become a member, you can do that by heading over here!
Photos: Chevrolet
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