No Auto 4WD, Vac Prob??
Thread Starter
|
Senior User
Joined: Sep 2003
Posts: 171
Likes: 0
From: SE Michigan
No Auto 4WD, Vac Prob??
Have 03 PSD F250 4WD CC...
Dishearteningly learned over snowy Holiday that 4WD does NOT engage when hubs in AUTO position (it clunks and I/P 'says' its in 4wd, but rear slides out). Later tried locking hubs manually, and 4WD DOES work then.
Tried it again in AUTO position over weekend, and heater was on HIGH on Floor. Upon turning 4WD (shift-on-fly) to 4-High, the heat went from Floor up to the Window/Defrost, and still no 4WD...
I've heard VAC operated Auto Hubs???
Truck is only 3 months old... is there Anything QUICK that I can check by myself prior to trip to the Dreaded Dealership...???
Friggin' $43K truck, No 4WD. WTF??
Thanks for advice.
Dishearteningly learned over snowy Holiday that 4WD does NOT engage when hubs in AUTO position (it clunks and I/P 'says' its in 4wd, but rear slides out). Later tried locking hubs manually, and 4WD DOES work then.
Tried it again in AUTO position over weekend, and heater was on HIGH on Floor. Upon turning 4WD (shift-on-fly) to 4-High, the heat went from Floor up to the Window/Defrost, and still no 4WD...
I've heard VAC operated Auto Hubs???
Truck is only 3 months old... is there Anything QUICK that I can check by myself prior to trip to the Dreaded Dealership...???
Friggin' $43K truck, No 4WD. WTF??
Thanks for advice.
Junior User
Joined: Oct 2003
Posts: 51
Likes: 0
These are definetely signs of a vacuum leak. Your defrost and vents are controlled by the vacuum. When you flip the switch to engage ESOF it opens a solenoid which should be located really close to the vacuum reservoir. If there is a leak on the other side of the solenoid, the reservoir will be emptied and the vents will go over to defrost mode. When you turn off the ESOF switch, you will have to wait several minutes for the small vacuum pump to pump out the reservior before the vents will work normally again.
The vacuum system is pretty simple. On the other side of the solenoid you have the vacuum line which goes to a T and then to each hub. Deep inside the hub there is a knuckle O-ring. This is not trivial to get to. There is the auto-hub itself which is each to take out. Apparently the outer o-ring on the auto-hub is a replaceable part but nothing within the auto-hub is.
The vacuum system is pretty simple. On the other side of the solenoid you have the vacuum line which goes to a T and then to each hub. Deep inside the hub there is a knuckle O-ring. This is not trivial to get to. There is the auto-hub itself which is each to take out. Apparently the outer o-ring on the auto-hub is a replaceable part but nothing within the auto-hub is.
Post Fiend
Joined: Jan 2002
Posts: 5,859
Likes: 7
From: USA
As yeti! said chk the vac at the hub ,you will see the hose . also chk the fuse that controls the esof
relay . The vacum system isn't hard to figure out .
Here's a problem that has been showing up alot at my buddy's dealership. The left over trucks that have been sitting on the lots are having alot of problems with the hub seal drying out from sitting on the lots and the first time guys try to auto 4wd the seal leaks .no 4wd
They have been soaking the front hub with wd-40
to soften the seals and keep them from doing this.
Spray silcone also works !
Just some comments but if its under warranty take it in ask for a loaner while they have yours
Rich
relay . The vacum system isn't hard to figure out .
Here's a problem that has been showing up alot at my buddy's dealership. The left over trucks that have been sitting on the lots are having alot of problems with the hub seal drying out from sitting on the lots and the first time guys try to auto 4wd the seal leaks .no 4wd
They have been soaking the front hub with wd-40
to soften the seals and keep them from doing this.
Spray silcone also works !
Just some comments but if its under warranty take it in ask for a loaner while they have yours
Rich
