Join Date: Nov 2004
Feedback Score: 0 reviews
Think of the hublocks as click type ball point pens. Push them on with a vacuum pulse, push them off with another. The solenoid provides 15 inches of vacuum to apply and 7 inches to unapply. Any leak will stop operation of both hublocks as they are tied together. Lines, vacuum hub seal failure due to bad ball joints, wheel bearing failure, solenoid failure, hublock failure of their vacuum diaphragm, torn hublock or wheel bearing o rings, vacuum pump failure.... the list goes on. Buy a handheld vacuum pump with guage. disconnect the lines at the solenoid. Check for adequate source vacuum once the pump turns off- over 15 inches Hg. If that is fine, put the source vacuum back on the solenoid and the pump gage on the outlet of the solenoid. Check for 15 inches to apply and release in 4x4 and 7 to apply and release in 2wd. The 4x4 module can hold one on or off till a timer has elapsed, IIRC 2 minutes. If you got good readings there, you have a leak somewhere in the hublocks/bearings/lines. Remove each line at the spindle. block with a golf tee or something of the like. apply hand pump vacuum to check the integrity of the lines. Check each hub with the hand pump. Should hold 15 inches Hg with no leaks. Do this with the wheels off the ground and spin them hublocks engaged and disengaged. You will find your fault eventually.
Dad always said,"Knowledge is limited but stupidity knows no bounds."