Intermittent whistling sound

I have an 02 Dakota Club cab with the 5.9L V8 engine with 70K miles on it.
I love this truck but it recently started with this whistling sound coming from the engine compartment.
When the sound comes up, I can lessen it or make it go away by either accelerating or taking my foot off the gas. I have checked the oil and the level is fine. I'm just about at 3000 miles since maintenence and am due for an oil change again. I live in Minnesota and give it about 10 to 15 minutes to warm up before driving. It does seem worse when the engine is cold if that helps at all. There are no other noticible effects other than the sound.
Any thoughts or comments would be appreciated.

I have a 90 club cab with a 2.2 4cyl. I hear the same whistle, I think. It is subtle and by pressing the gas pedal, I can stop it or increase it. I think it is due to wind going thru vents or the state of the art aerodynamics of this vehicle. ;-)

-Tom

Mine actually just started, so I don't think it is the wind. If I step on the gas or let off on the gas it subsides or goes away. I'm going to get the oil changed and see if that makes a difference and I'll post back an update.

Same problem after the oil change. The PCV valve was original so I replaced that and the air filter. The problem went away for a few days only to return worse than ever. Yesterday I noticed a small power steering fluid leak on the driveway and there is now a subtle grinding sound coming from the power steering pump. I am going to replace the pump this weekend if this Minnesota winter cold lets up a little. I'll repost back with the results.

I recently posted a similar problem. The whistle has gone away with the recent warmer temps (25 and up). I am going back to my dealer in the next few weeks to see if they can find anything since I have 2,500 miles left on my warranty. I will let you know if I get any results from that.

Well I replaced the power steering pump and the problem still exists. It is practically gone when the weather is warmer. Anybody else have an idea?

I would suspect a vacuum leak, check all hoses, booster, pvc, breather, evap system. I would also make sure that you remove the hat from the throttle body and make sure the gasket is not missing.

have you checked the P.C.VALVE????????

Yes, The PCV valve was replaced. It made no difference,

I had the dealer take a look when I had it in for other service. They say the PCV valve is rattling, even though I just replaced it. I will replace it with one from the dealer. Then I'll probably have to wait until fall/winter to see if it still happens.

I do not know if you have solved this problem just yet. I did have that exact problem that occured at those RPM's and when the weather was cold. It really got bad when the weather was even colder. The alternator bearing grease seemed to be the culprit, some Dodge dealers know about it, not all. Once the bearing was replaced by my local overhaul shop the sound has never come back. It is less expensive if you can get this done vice replacing other components as long as it works.

Jerry

Not resolved yet, but now I am having other problems (sounds like belt squeal even the the serp belt was replaced about 8 months ago), and the alternator is making more sense and hearing the info from you. Thanks for your input. I will update this thread when I have more info.