2003 Ford Expedition 4WD

JIMS1985NIH

MEMBER
2003 FORD EXPEDITION
5.4L
V8
4WD
AUTOMATIC
135,500 MILES

The transfer case is engaging when put in 4 hi or low but the front hubs are not locking in there is no vacuum coming out of the hoses that go to the front hub not sure why there is none is there some where that it comes from that I might not be looking at, I have put a new motor on the transfer case as well as putting a new vacuum piece out under the hood behind the battery, not sure where else to look for problems that might help me solve this issue

1 Reply

HMAC300

MECHANIC
48,601 POSTS

Try this, it's a tip about noise but may be the same problem you ar facing is a vacuum leak at solenoid at right rear of engine bay.
Do not jump right into the service bulletin (03-6-4) about installing the "s" spring in the front diff, if you have the situation about hub noise when in two wheel drive high, disconnect the vacuum lines at the solenoid on the right rear corner of the engine compartment and plug vacuum leak. Drive vehicle again, if noise continues, than start at the front diff. And follow service bulletin. This one here has a slow leak in the solenoid (takes approximately 10 minutes of driving before noise is heard) which allows little vacuum to get to the front hubs and partial engagement occurs creating your grinding noise. If the customer is cheap and or wants to spend as little money as possible, if you leave the vehicle in AW4WD or 4X4 High noise will disappear.
Just disregard the service bulletin thing as you are talking about not engaging and looks like this is what it effects.