For the past week or so, my truck has been making a whirling sound wen it is first started up in the morning, and when I first start it up when leaving school. It continues to make this sound whenever I am idling anduntil the engine has some time to warm up. After it getrs warmed up the sound slowly goes away. But at ilde it is the worst, giving it revs at a stop in park the sound grows fainter and then returns to it's worst point at ilde.Any ideas, the belt has been replaced about 6-7 months ago. So it shouldn't be the problem. I haven'thad a chance to check any vaccum lines because of the persistent cold here. Again it only seems to happen when the engine is first started, after about 2-3 minutes of driving, it goes away. Someone i know suggested a heater vaccum line, but i don't know if these truks still use those, do they? Because i turn defrost on low until engin is warm then, i full blast it to clear windows and for heat. The sound to be more descriptive, sounds like i have oneof the old belt drive superchargers on it. And the sound revs up like those blowers d too. Any suggestions. 1992 5.2L magnum with A/C also.

 

Getcha apiece of garden hose and hold to your ear for a stethosope. Listen to the alt, idler pulleys etc. Nothing? Do the same around the intake. Nothing? Slide under the truck and see if it sounds like the pump in the trans. A long screwdriver also makes a good stethoscope.