Crazy 4 wheel drive prob
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Crazy 4 wheel drive prob
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I have a 1997 Expedition EB 4x4. When I engage the 4 wheel drive, I can here the transfer case shift, the dash light comes on, and when in 4L, I can feel the difference in the lower gear ratio. However, the front wheels have no power. It is basically a 2WD. What in the heck is going on here?
Thanks,
Chris
I have a 1997 Expedition EB 4x4. When I engage the 4 wheel drive, I can here the transfer case shift, the dash light comes on, and when in 4L, I can feel the difference in the lower gear ratio. However, the front wheels have no power. It is basically a 2WD. What in the heck is going on here?
Thanks,
Chris
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If it will go in 4WL, then the problem is with the front drive line. The front drive is actuated by a vacuum motor at the front differential. The vacuum is controlled by 2 small black vacuum solenoids on the upper part of the firewall near the fender on the passenger side. The one on the inside with the pink line engages the front driveline, the outboard one with the blue line disengages it to put it in 2WD. If you remove the hose connectors from the valves, you can use a vacuum tester to check for leaks in the plumbing. I had the same problem on my 97 XLT. I had to replace the vacuum lines from the valves down to the connector at the front of the fender well (parts cost about $20). These lines run under the inside edge of the battery tray and, over time, will get very brittle and crack or break. About 2 months later, I had to replace one of the vacuum solenoids (parts cost about $30). Both tasks take about an hour each. Works like a champ, now.
Tuned
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From: north carolina
Well, at first I was going to say its probably a sensor issue. But, then you said that 4LO works out of the transfer case. So, you know at least the transfer case is delivering 4LO power to the rear wheels.
If no power is being delivered to the front wheels, and with the logic above that the transfer case is doing its job, then it sure sounds like a mechanical issue in the power train to the front wheels, either in the differential or the wheel hubs. Put it on a rack, and observe the front drive shaft and axles to see if they spin when in 4HI or 4LO.
If no power is being delivered to the front wheels, and with the logic above that the transfer case is doing its job, then it sure sounds like a mechanical issue in the power train to the front wheels, either in the differential or the wheel hubs. Put it on a rack, and observe the front drive shaft and axles to see if they spin when in 4HI or 4LO.
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WOW!! Great responses, and much thanks. I brought old faithful to my local mechanic who in turn put in on the rack. We put in in 4LO...the transfer case engaged...the back wheels spun...the front shaft turned, and guess what? The front wheels did not. I am going to try the vacuum hoses. Might as well replace them and the solenoids why I'm at it. Both seem cheap enough. The dealer wanted $100 bucks to diagnose the problem. I can change the vacuum hoses and solenoids for that. Hey jcbfd, do you know any part numbers, and where did you purchase your parts?
Thanks,
Chris
Thanks,
Chris
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Upper Tube Assembly is F75Z-3A788-AA
Vacuum Valve is E8AZ-9H465-A
Got them from my local ford dealer. Look closely at the valve. There's a tab on the back you release then push down on the valve to remove it from the mounting plate. You do not have to remove the mounting plate to replace the valve(s). Both valves are the same part number.
Vacuum Valve is E8AZ-9H465-A
Got them from my local ford dealer. Look closely at the valve. There's a tab on the back you release then push down on the valve to remove it from the mounting plate. You do not have to remove the mounting plate to replace the valve(s). Both valves are the same part number.
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Thanks for the help everyone. When I'm off on Monday, I will be bathing in elbow grease. I'll let everyone know the outcome.
Thanks a million!
Thanks a million!
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Just to let everyone know, the vacuum hose under the battery compartment had a giant hole in it. Looks like acid from an old battery got to it. Replaced the hose and everything worked great. Thanks for all the input.
--Chris
--Chris
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