LQ4 Vortec 6000 whining noise low RPM's!

[996]

Hello all. I have looked and posted in other GM forums, but haven't receive much help!

My problem is as follows. My GMC Yukon Denali '04 has recently been giving me a few problems. Mostly wear and tear, but this one is prominent and is not going away. I have had it checked out by my local trustworthy shop and they say it is a noise coming from my intake system. I have an AEM CAI (short ram).

The noise is a loud whining noise that is really loud between 1,000-2,000 RPM. I thought it may be from the alternator, but it doesn't seem like it. (I replaced the alternator about a year ago). The truck has 140k miles on it. I checked my intake and everything seemed to be sealed up tight without any air leaks. The noise is always there, but loudest at the above mentioned RPMs. It began about 10k miles ago.

I am concerned and willing to do what ever it takes to address this problem. I was wondering what potential factors or parts could be causing this noise so I can test each one to figure it out!

Thank you all in advance!

 

[Sasquatch]

What i would do is take off the serpentine belt and the A/C belt and briefly start the engine to see if the noise stops. If it does then you know it`s coming from either the power steering pump, water pump, alternator or either of the belt tensioners. Then spin all the pulleys with your hand to see if you can hear anything.

I had a similar sounding noise a while back and it was the belt tensioner for the serp belt but spinning it by hand made no noise. I thought it was my A/C tensioner and replaced that but it was the other one but they`re cheap so it wasn`t a big deal.

Good luck.

 

[996]

What i would do is take off the serpentine belt and the A/C belt and briefly start the engine to see if the noise stops. If it does then you know it`s coming from either the power steering pump, water pump, alternator or either of the belt tensioners. Then spin all the pulleys with your hand to see if you can hear anything.

I had a similar sounding noise a while back and it was the belt tensioner for the serp belt but spinning it by hand made no noise. I thought it was my A/C tensioner and replaced that but it was the other one but they`re cheap so it wasn`t a big deal.

Good luck.

Cool thank you for the reply. So when the belt is off and I don't hear the noise anymore... I spin each of the pulley's by hand. Will me spinning a pulley by hand cause it to make the noise it is normally making with the belt on?

Thanks!

 

[Sasquatch]

Spinning them by hand won`t make the same sound because the tension from the belt isn`t there. You can spin the tensioners fast and they should be dead silent. The A/C compressor and alternator you can also spin but the power steering and water pumps don`t spin freely.

It`s just a process of elimination. I bet it`s one of the tensioners or the A/C.

 

[996]

Spinning them by hand won`t make the same sound because the tension from the belt isn`t there. You can spin the tensioners fast and they should be dead silent. The A/C compressor and alternator you can also spin but the power steering and water pumps don`t spin freely.

It`s just a process of elimination. I bet it`s one of the tensioners or the A/C.

So I slipped the belt off and ran the car. The noise was not there anymore. So it must be one of the accessories. When the belt was on, I checked all the pulleys and how they were sinning. Everything seemed okay. The alternator was making some noise close up, but I think that is normal. I spun the tensioner pulley and it was spinning fine, but making a louder noise than the other pulleys (probably because it isn't connected to something else)...like an alternator or water pump.

Now my problem is how to figure out which accessory is the actual problem.

Thank you guys for the help!

 

[Sasquatch]

I would start with the one that was making noise. When mine went bad it spun freely but you could hear it. That little noise you hear is amplified when the tension is on it. They should spin silently with the belt on and off.

At least you`re in the ballpark now, Good luck.

 

[Mr. 960]

my bet is the power steering pump!

 

[996]

my bet is the power steering pump!

Hmm. I had my power steering pump rebuilt about 40K miles ago. If the pulley is bad, can that just be replaced? Or does the whole thing need to be replaced?

Thanks for the comments guys!

 

[Sasquatch]

The power steering pulley is on a shaft so unless it`s bent it would be the pump itself that`s bad.

Like i said earlier, Start with the cheap stuff to replace like the tensioners. I think both of them are about $50 total and are very easy to change.