I have 2500 miles on my 2 week old truck.! I have had a "power steering" type of whine/noise (Sounds very similar to low power steering fluid, but it's not the power steering unit) and slight vibration in the brake pedal (same frequency of vibration as the whine I'm hearing), all while braking moderately to hard (gets louder/worse the harder you step on the brakes) while the engine is in at an elevated RPM range. It seems only to happen once the truck is at operating temperature/been driven for a while. Also, when the truck is in it's "mood" to make this noise, I can duplicate it by pressing on the brake pedal and pressing the gas pedal at the same time to elvate the RPM's, but while the truck sits still and doesn't move. As stated above, the more the RPM's are raised the louder the noise gets, and stops immediately when the brake is released or the RPM's go down (back to idle if sitting still, or when you are done coming to a stop if done while moving) It doesn't matter if the truck is in gear or neutral, I can still create/duplicate this noise. I don't think it has anything to do with the tranny since I can duplicate the noise in neutral. What do you think? Do you think it has something to do with the antilock/brake system? I'm at a loss! I don't notice any performance issues with braking, engine/power or tranny. And if someone says that this is normal, I say that this is definately louder than any normal noise I've ever heard from any vehicle and extremely noticeable. It was loud enought that the first time my wife heard it, without previous knowledge of the problem, she looked at me and asked what that noise was. What ideas do you all have. All input will be very much appreciated.

I just got done talking to my Uncle who is a self employed mechanic (no GM Certified type of guy), and he seems to think that from the explanation of my problem, that is does have something to do with the power steering unit. He says that all new vehicles get their brake assist/boost from lines that are routed from and off of the power steering unit; ie, no more vacuum assist brake units. He seems to think that while my problem only appears when the brakes are applied, that it gets louder with the more pressure to the brakes (meaning that the master cylinder is asking for more boost from the power steering unit), that I can feel the vibration in the brakes, and that it sounds like the power steering unit, that it is linked/related to the power steering pump. Anybody agree, disagree, have any other ideas. I just want to be able to help identify the problem and give my "Stealer" a better starting point when I take it in, becuase you know how things can be with them; "Oh, we can't duplicate the problem, everything seems to be fine!" Let me know what you all think.

I've got the same problem. Did it real bad when I first got it, then stopped for a while, now it does it every once in a while (which makes it useless to take it to the stealer because it's hit and miss...). There was a thread about this before, will have to dig to find it.

I've been digging and haven't found anything yet. Please let me know if you find anything and I'll do the same. But your right, it is hit and miss, which makes it difficult to duplicate at the Stealer. Thanks for the input!

Here it is:

http://www.dieselplace.com/forum/showthread.php?t=35911&highlight=yosemite

Not sure if this is exactly the same problem that you are having, but sounds similar...

It sure does sound like the exact same problem! Thanks for the link to the new thread. I posted a reply at that thread already asking for help.

Guys,
Been there and fixed this problem. My truck is now one of the only6.6l duramaxes to have a power steering cooler from an 8.1 l engine fitted.This dropped my power steering fluid temperatures 47degrees f. The Duramaxes for some reason do not come with a power steering cooler so on long extended rpm operation the fluid gets way to hot and starts to aerate causing cavitation. see if your trucks are noisy when the fluid is cold. They will probably be a hell of a lot quieter until that fluid gets hot. Temp drop at the reservoir went from 177 degress to 130 degrees after cooler was installed .As a side note the tests the dealer performed on the hydroboost revealed a less then adequate flow indicating internal restriction within the unit. They also replaced that. I am 99 percent sure this with the cooler addition will fix your problem.

Good luck
Laker

MY did the same thing when i left the dealer, upon taking it back at 500miles the hydroboost actually cracked up on the firewall and had to be replaced. Went to have the hood adjusted and opened hood to a mess of fluid everywhere!!!

I have the same problem.
mike

Same problem here, I almost thought I didn't have brakes when it happened- stopping from an exit off the freeway.

Has Anyone Had A Dealer Install The Steering Cooler Under Warrenty Or Replace The Hydroboost? What Do I Need To Tell Them To Get This Fixed My 3 Week Old 05 Has The Same Problem?

I wonder if changing out the power steering fluid to a synthetic type fluid would help??

I took mine to the stealer, and was given the standard " it's normal" So what's the secret code to get them to fix it, even though we all have the same problem?

Don't know, we are all still trying to find that out.

Any other info on this problem, I still haven't found a fix?

Mine does it too. I tend to notice it most when going around 10 mph and turning a sharp corner. It groans but doesn't seem to cause any problems. I have checked my PS fluid and it's fine.

Would changing the fluid do anything?

So, this noise is normal? Mine did it the first time (1500 mileage) coming down the West side of the Sonora Pass in CA, which is an 7 to 8 percent 10 - 15 mile downgrade with many, many tight turns. I was in T/H mode, using the brakes, and dozens of tight turns. Got down to the first flat spot and the noise was so bad I pulled off and raised the hood. Sounds exactally like a power steering unit that is low on fluid. I noticed that the noise came on strong while steering around the turns and braking. While on the side of the road with the engine idling, the noise was there, but not loud. However, when my friend raised the RPM to 1500 it became the loudest. Later, as we drove and things cooled off, the noise completely dissappeared. I did not get the noise after freeway driving and not touching the brakes. Build date is 02/05 in Flint, MI.

Jimmy
Sandstone Metalic, K3500 Crew Cab, Long Bed Dually

Both my 03 and 04 make the same noise. Mostly when in hot weather and on long trips under hard braking. ie freeway exit etc...