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Hello. I have a 2004 Chevrolet Silverado 2500HD 6.0. It has been making a high pitch noise, but only at cold start with temperatures below freezing. It lasts approximately 10-30 seconds. I can’t seem to locate where the trouble is coming from under the hood. Power steering fluid levels are good. Antifreeze levels are good, both in the radiator and the reservoir. It doesn’t matter if I run the heater or not, at start it happens either way. It doesn’t really sound like a belt issue. My novice ear hears metal. But I am not 100%. My best description is high pitch. I have been searching other forums and haven’t found any other trucks like mine with this issue. However, other vehicles of different makes and models are showing this problem. On those vehicles, it was suggested to check the secondary air pump bearing, replace the air valve or air check valve- asap, check belts for glazing, I do have heat. No check engine light. Battery is good. For some reason, and I don’t really know why, I’m leaning towards the alternator.??? …I’m just wondering if you have any ideas that might help me at this point to identify what’s going on. I don’t want to break something that’s going to cause me worse problems in the future.
Thank you,
Elizabeth
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my guesses are the tensioner (if it has a spring loaded one) if its an adjustable set up check the idler. the the belt off and spin the pulleys feeling for anything out of the ordinary. that’s a good place to start
i have moved this topic to service repair questions.
also we can better identify the sound if we can hear it, if you can make a video we can better give you an idea.
[quote=”ElizabethS” post=156264]Hello. I have a 2004 Chevrolet Silverado 2500HD 6.0. It has been making a high pitch noise, but only at cold start with temperatures below freezing. It lasts approximately 10-30 seconds. I can’t seem to locate where the trouble is coming from under the hood. Power steering fluid levels are good. Antifreeze levels are good, both in the radiator and the reservoir. It doesn’t matter if I run the heater or not, at start it happens either way. It doesn’t really sound like a belt issue. My novice ear hears metal. But I am not 100%. My best description is high pitch. I have been searching other forums and haven’t found any other trucks like mine with this issue. However, other vehicles of different makes and models are showing this problem. On those vehicles, it was suggested to check the secondary air pump bearing, replace the air valve or air check valve- asap, check belts for glazing, I do have heat. No check engine light. Battery is good. For some reason, and I don’t really know why, I’m leaning towards the alternator.??? …I’m just wondering if you have any ideas that might help me at this point to identify what’s going on. I don’t want to break something that’s going to cause me worse problems in the future.
Thank you,
Elizabeth[/quote]this is a real longshot but try turning all the high draw electricial devices on right after startup to load up the alternator wipers high fan headlights with high beams see if you can get the noise to change at least it will point you in the direction of it being something belt driven. But if it were me id just ride it out till it rears its ugly head a little more frequently and regularly
Thank you for giving me somethings to try to help more identify the direction I need to keep looking or rather leave alone. I really appreciate your suggestions.
-ElizabethPlease don’t run the engine with the Alternator disconnected it may cause damage to the alternator. What you describe though does sound like a slipping drivebelt struggling to drive the alternator.
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I second checking the tensioner. You may be able to confirm by removing the drive belt and checking the tensioner for rough spots or noise. Here’s some more information that might be helpful to you.
http://www.ericthecarguy.com/faq/diagnosing-noises-in-your-car
Please keep us posted on what you find.
I’ve disconnected the alternator every time I think it’s suspect haha. Never had any problems. I mean, if you leave it off for more than a few seconds I can understand, but all it takes is one second to listen if the noise continues or ceases.
The Blue BEAST finally gave in…it was the AC Belt Tensioner. Or at least I sure hope so. I am going to replace it here at the shop after work,along with the belt and hope it will solve my problem.
The “noise” stopped after the cold weather moved on and then reared it’s ugly head about 2 weeks ago. It came…it went…and then it returned in full force this morning. My fellow comrads at work agree it is the AC Belt tensioner. Not the water pump. Not the alternator.
Sorry about the video. I was going for more audio than video. Although I know it helps to be able to actually see the pulleys. I couldn’t get a good angle.
I’ll let you know how my wrenching goes. If I get a helper, I’ll try to get some good footage of the job.I am so happy to report that I fixed the problem. Turns out it wasn’t that hard to do. Definitely was the AC tensioner. That thing was flopping around like crazy. Switched it out. Threw on a new belt. And I’m good to go. It’s definitely a bonus having the truck lifted. I wish I had gotten a picture of me sitting under the truck. Sitting! 🙂 It made it so easy to change out the tensioner and get the belts back on. I really appreciate everyone’s advice! Oh yeah… I did discover my power steering pump is leaking somewhere. I couldn’t really see where. I am not having any whining issues and the leak is very very slow. Not dripping, I just noticed the moisture. I watched videos on changing this part out. Yeah!! Hoping it’s just a hose!
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