4wd not engaging - Diesel Forum

bigtbasser · 12-26-2008, 10:55 AM

2002 Super duty f250. The front hubs are not engaging when the dial in placed in 4wd. When I turn the hubs to the lock postition the 4wd works but not in the auto posistion. The fuses look good. What would be the sequence to run down the problem. Thanks T

**my03psd** · 12-26-2008, 11:45 AM

You have a vacuum leak somewhere.Does you're climate controls work,such as floor,face, or defrost?If they don't switch modes then perhaps a bad vac. pump.If they do work than you have leak somewhere.I had this problem after my balljoints were replaced.Hope this helps.

diccou · 12-26-2008, 05:33 PM

Turn the knob to 4X4 high,pull the vacuum line off one of the hubs if you have strong vacuum you have bad hub seals if you have no vacuum its the electric pump

My04_6.0PSD · 12-26-2008, 07:16 PM

Too familiar...Same thing happened to me after ball joints replaced. I learned a lesson on who can touch my baby. Show me a certificate, give me 3 references, etc...

In my case, they seemed to have used a chisel to take the hub off to service the ball joints. This left a nasty dig at the o-ring seal. Oh yeah, they also forgot to replace the o-ring and the hub-axle seal (probably has a special name), and you got to replace that stuff when you take off the hub. So one or the other, or combination of both, and you get no vacuum to the hub and no auto 4WD. In the end, what I had hoped to be a simple alignment job turned out to be a $2,000 lesson. Hope yours doesn't cost you that much, or you can fix it yourself!