Hello all, its been a while since I have visited the site since the truck has been running fine... until lately. 70,000 miles had to have the water pump and power steering pump replaced. Replacing the water pump solved the coolant leak. But I continue to have this noise that I thought was the power steering pump. New pump same old sound... I suspect it relates to the hydro boost assisted brakes. It sounds like a bad power steering pump that changes as the engine RPM changes, you know wwrrrrrrrrrr. You don't have to be moving for the sound to happen, just rev the engine in park and you can hear it. If you step on the brakes you can hear the sound change frequency. Any ideas? If a new power steering pump is installed wouldn't a mechanic us new power steering fluid? Any comments would be appreciated. Thank you.