4x4 Not Engaging
Post Fiend
Joined: Nov 2002
Posts: 9,987
Likes: 7
From: Memphis, TN
4x4 Not Engaging
strengthtrusthonor
Your problem sounds like the vacuum actuator on the front axle. You have no locking hubs and the fact that you CAN go to low range says your t-case shift motor (not a floor lever) is working.
Your problem sounds like the vacuum actuator on the front axle. You have no locking hubs and the fact that you CAN go to low range says your t-case shift motor (not a floor lever) is working.
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New User
Joined: Dec 2002
Posts: 12
Likes: 0
From: Lexington USA
4x4 Not Engaging
Thanks, Steve... the vacuum actuator. Do you have a schematic/picture of where this is located and how to test it? Replacing/repairing this would take less time than draining the t-case... again thanks.
New User
Joined: Feb 2000
Posts: 16
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4x4 Not Engaging
My four wheel drive just won't engage. The t-case seems fine. And the vacuum actuator on the axles seems fine; tested it with a hand vacuum pump.
Lately (since we have gotten snow), I have been trying the 4x4. It seems that it will engage but is slow. I put a gauge on the the on the vacuum line to the solenoids. It only read a couple of inches of Hg. My latest theory is that this is not enough vacuum to operate the actuator. Next time I have a chance, I will connect to a stronger vacuum source (if I can find one) to see what happens. Maybe there is a cracked line somewhere.
strengthtrusthonor,
Yours sounds like a mechanical problem. The t-case in my 74 Bronco would pop out when under power. Installed a rebuilt one and the trouble stopped.
The vacuum actuator is on the top of the axle under a plastic cover. The solenoids that control in are on the fire wall, far passenger side.
Lately (since we have gotten snow), I have been trying the 4x4. It seems that it will engage but is slow. I put a gauge on the the on the vacuum line to the solenoids. It only read a couple of inches of Hg. My latest theory is that this is not enough vacuum to operate the actuator. Next time I have a chance, I will connect to a stronger vacuum source (if I can find one) to see what happens. Maybe there is a cracked line somewhere.
strengthtrusthonor,
Yours sounds like a mechanical problem. The t-case in my 74 Bronco would pop out when under power. Installed a rebuilt one and the trouble stopped.
The vacuum actuator is on the top of the axle under a plastic cover. The solenoids that control in are on the fire wall, far passenger side.
Logistics Pro
Joined: Sep 2002
Posts: 4,410
Likes: 1,015
From: Central KY
4x4 Not Engaging
Yeah, sounds like the little engage-motor in your front differential is dead. This happened to me on my Z71 pickup years ago...it went out during a snowstorm. (Damn GM junk). But anyway, GM replaced the little factory gas-operated motor with an electric one. It just slid right into a hole and screwed in where the front diff. is. Then you just connect the wiring harness and you are ready to go. I think the one for my truck then was like 60 bucks or something. It's a job that could be done in 30 minutes or less on a GM truck...so I am assuming it should take less time on a well-engineered Ford :-X12
Good luck.
Good luck.
Post Fiend
Joined: Nov 2002
Posts: 9,987
Likes: 7
From: Memphis, TN
4x4 Not Engaging
The OE GM actuator is an oil-filled cylinder with a little heating coil inside. When power is sent thru the coil, the oil expands & pushes a piston that engages the axle. Of course, if it's cold outside or if you drive in snow, you lose 4WD. 
:-X23 You can find MANY aftermarket fixes, including vacuum, cable, and solenoid actuators.
GM 
:-X23 You can find MANY aftermarket fixes, including vacuum, cable, and solenoid actuators. GM
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New User
Joined: Dec 2002
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From: Lexington USA
4x4 Not Engaging
Does anyone have a schematic/drawing/photograph of these components on the truck? (solenoid, vacuum motor, etc..)
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Post Fiend
Joined: Nov 2002
Posts: 9,987
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From: Memphis, TN
4x4 Not Engaging
You can almost certainly get a CD for your truck (and all other trucks & vans of that year) off eBay for under $10. I have 3 and to me, they're worth about $20ea after shipping, so that's how I'd recommend you bid.
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New User
Joined: Dec 2002
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From: Lexington USA
4x4 Not Engaging
Okay, let me get all this straight. After reading through all of the postings, I'm seeing several different ideas.
Considering that I have a 1997 F-150, the low gear engages fine, but the 4x4 seems to 'pop' out under high torque or sharp turn, does the group feel that the problem is:
1.) In the vacuum motor/lines
2.) In the transfer case/center connect/disconnect
3.) In the floor-mounted shift lever
I bought the CD for f-150 troubleshooting and it's on the way. Still, I'd like your opinion/expertise. Thanks...
PS. I've learned alot from you guys (about locking hubs, etc.) so I'm really thankful for the website. All except for those little annoying faces over there on the left. Here, I'll use my first one ever:
(What the heck is he doing?)
Considering that I have a 1997 F-150, the low gear engages fine, but the 4x4 seems to 'pop' out under high torque or sharp turn, does the group feel that the problem is:
1.) In the vacuum motor/lines
2.) In the transfer case/center connect/disconnect
3.) In the floor-mounted shift lever
I bought the CD for f-150 troubleshooting and it's on the way. Still, I'd like your opinion/expertise. Thanks...
PS. I've learned alot from you guys (about locking hubs, etc.) so I'm really thankful for the website. All except for those little annoying faces over there on the left. Here, I'll use my first one ever:
(What the heck is he doing?)
Postmaster
Joined: Jul 2001
Posts: 4,038
Likes: 3
From: South Kitsap County, WA
4x4 Not Engaging
I'd say it's whatever holds that shift fork in place and the shifter's engagement, probably just an adjustment as it engages sometimes, also make sure you jam that shifter home as the 4H position is al the way against the stop for neutral. You apply torque and it wants to shift out... so the 4L is being held in by the oddball zig-zag in the shift pattern.
-Kerry
That little guy is obviously enjoying himself... They emoticons are there to help aleveate the lack of face to face/in person talking. No facial expressions? then how do we know if a person is being funny or just a jerk.
-Kerry
That little guy is obviously enjoying himself... They emoticons are there to help aleveate the lack of face to face/in person talking. No facial expressions? then how do we know if a person is being funny or just a jerk.
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