dieseldoc Posted July 17, 2019 Share Posted July 17, 2019 Have a 2008 F-350 with a 6.8 and auto with esof. The both hubs will not unlock. I have been through the pinpoint tests, with no results. Electrically things are right on. Tested vacuum supply to the pvh solenoid, 20”, tested vacuum to the hubs, 20” when switch is turned to 4x4. Switch it back to 2wd and I only get 4-4.5” to the hubs. Checked the vacuum at the hose at the solenoid with the same results. I thought perfect it’s not the right vacuum to release them. Tested for leaks and it will hold 6” for 10 minutes, holds 20” for 10 minutes without a drop. I have tried driving it some thinking torque wrap or something is keeping it from releasing. I applied 6.5” of vacuum to the hubs with my mityvac and still won’t unlock. Both hubs are in auto. Ordered a new pvh solenoid for just in case. I’m thinking there is something in the hubs causing the trouble.......... wierd that both sides would have a problem though. Open to suggestions or what have I missed? Thanks fellas Quote Link to comment Share on other sites More sharing options...
forddieseldoctor Posted July 17, 2019 Share Posted July 17, 2019 They will not actually unlock until after the lower vacuum is released. Quote Link to comment Share on other sites More sharing options...
dieseldoc Posted July 17, 2019 Author Share Posted July 17, 2019 Hahaha. I figured that out after I posted this questions. I can unlock em with my mityvac but the pvh solenoid does not unlock them. Only puts 4” at the hub and vents and they won’t unlock. Hoping the new Ford pvh will do the job. The current issue me is aftermarket. Quote Link to comment Share on other sites More sharing options...
forddieseldoctor Posted July 18, 2019 Share Posted July 18, 2019 Wouldn’t be the first time I’ve had one of those vacuum solenoids not put enough vacuum out. Quote Link to comment Share on other sites More sharing options...
8WA Sman Posted July 18, 2019 Share Posted July 18, 2019 WSM spec for unlock is 5.9 to 7.1 in Hg. I use 7 in Hg. when testing operation with a vacuum pump Quote Link to comment Share on other sites More sharing options...
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