أشكرك MNA... وجدت قبل قليل TSB من GM تذكر نفس مشكلتي، و لكن يبدو أن حلهم مؤقت و هو استخدام زيت دركسون Valvoline و هو غير موجود لدينا في السعودية (على حد علمي) للأسف.
Document ID# 2056814
Subject:Power Steering Whine Noise - keywords fluid gear hose idle pump turn #PIT4208A - (02/01/2008)
Models:2003-2007 Cadillac Escalade, ESV, EXT
2003-2007 Chevrolet Avalanche, Silverado, Silverado Classic, Suburban, Tahoe
2003-2007 GMC Sierra, Yukon, Yukon Denali, Yukon XL, Yukon XL Denali
2003-2007 Hummer H2
This PI was superceded to change the recommendation statement. Please discard PIT4208.
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
Some owners may comment of a power steering pump whine noise. After normal diagnostics you may find the noise to be coming from the power steering pump. This whine noise is most commonly heard between idle and 2000 rpm coming from the power steering pump.
Recommendation/Instructions:
GM Engineering has not evaluated this concern, but reports from GM Dealers of flushing and refilling the power steering system with Valvoline SynPower Power Steering Fluid have reduced or eliminated this noise. Valvoline SynPower Power Steering Fluid is a synthetic fluid and is available at most auto parts stores in quart size containers. In most cases 3 or 4 quarts will be needed to flush and fill the system.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.
GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
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Document ID# 2056814 
