Hi,
I have been hearing this howling bottle top sound in my volvo xc70 2005 it is very sporatic it comes and goes on hilly turn. I have replaced the brake booster and the noise continues. The tech has checked and see no leaks or cracked hoses he is as puzzled as i am I looked up one of the threads and saw that low power steering fluid could be the cause and the power fluid is low.Any help would be greatly appreciated