Diagnosed and repaired grinding IWE noise on left turns

[AWAR]

The initial problem was a slight grinding on slight left turns at highway speed. I engaged 4awd and the noise disappeared. I next replaced the 1/4” vacuum check valve and replaced the tees that changed hose sizes with all 1/4 x 1/4 x 1/4”. Still had noises in 2wd. Next I purchased a new hand held vacuum pump to aid in diagnosis. I tested each IWE separately and both passed. Then I applied 25” vacuum to the hose harness with both hubs attached. I turned the wheels both right and left and the vacuum held at 25. I next checked the vacuum supply to the hose harness through the solenoid valve. Got 15” of vacuum, should be more than that at my 1250ft elevation. As I moved the hard line between the hose harness and the solenoid the vacuum dropped to 5”. I found the 1/8” hard plastic line cracked where it is next to the battery. A quick cut and install some 1/8” fresh vacuum hose now I get a steady 20” vacuum to the hose harness. Problem solved.