Need Help Please!!!
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Junior User
Joined: Dec 2001
Posts: 52
Likes: 0
From: Itasca USA
Need Help Please!!!
Hey guys I just bought a 1997 F150 5.4 automatic with floorshift 4x4...and I got a problem.
The frontend wont engage?... No outta wack noises or anything except the little click when the transfer case first locks in. I have locked into 4high and 4low and the transfer case is working. The front driveshaft is spinning when locked in both 4high and 4low, and not when just in 2wheel drive. So I figured I have a problem in the front diff. I checked all my fuses and they are good. I did get ticked off enough just to look for vacuum pumps,relays ..that sort of thing. I found a vacuum pump on the passenger side of the front diff.(small round disc pump with 2 vacuum hoses)------WHAT DOES THAT PUMP DO?
My boss has a 2000 F350 powerstroke 6-spd 4x4 and we have vacuum problems all the time when in 4by like with the air-conditioner vents changing from vent to defrost on there own espesially when in 4low
I have a 1992 f150 4x4 so I know the components of the old school 4x4 frontend.
Thanks a lot guys any help would be awesome and greatly appreciated
The frontend wont engage?... No outta wack noises or anything except the little click when the transfer case first locks in. I have locked into 4high and 4low and the transfer case is working. The front driveshaft is spinning when locked in both 4high and 4low, and not when just in 2wheel drive. So I figured I have a problem in the front diff. I checked all my fuses and they are good. I did get ticked off enough just to look for vacuum pumps,relays ..that sort of thing. I found a vacuum pump on the passenger side of the front diff.(small round disc pump with 2 vacuum hoses)------WHAT DOES THAT PUMP DO?
My boss has a 2000 F350 powerstroke 6-spd 4x4 and we have vacuum problems all the time when in 4by like with the air-conditioner vents changing from vent to defrost on there own espesially when in 4low
I have a 1992 f150 4x4 so I know the components of the old school 4x4 frontend.
Thanks a lot guys any help would be awesome and greatly appreciated
Last edited by Racerguy; Dec 17, 2004 at 08:32 AM. Reason: language filter
Logistics Pro
Joined: Jul 2002
Posts: 4,821
Likes: 19
From: South Dakota
That pump actuates the 4x4 in the front differential, it moves a fork or collar (i'm fuzzy on this part) and creates a link between the drive shaft off of the transfer case to the left and right axel shafts.
Hopefully Racerguy will swing by shortly to help you troubleshoot it, might not hurt to try to do a search, I'm sure that it's been explained several times.
Hopefully Racerguy will swing by shortly to help you troubleshoot it, might not hurt to try to do a search, I'm sure that it's been explained several times.
Hotshot
Joined: Aug 2002
Posts: 12,679
Likes: 15
From: BC, Canada
That "pump" is actually a vacuum motor.
Like Super said it moves a shift fork and collar to lock the axle to the diff.
When you put it in 4x4 the vacuum motor should pull on the lever that sticks out of the housing to lock the axle inside. If the vacuum motor works but the axle still isn't locked then you probably have a shift fork problem inside the diff.
Like Super said it moves a shift fork and collar to lock the axle to the diff.
When you put it in 4x4 the vacuum motor should pull on the lever that sticks out of the housing to lock the axle inside. If the vacuum motor works but the axle still isn't locked then you probably have a shift fork problem inside the diff.
