Few questions..

[jsawyer1181]

I have a 1998 expedition 4x4 with the 5.4. This is gonna have a few questions so bear with me. First, the rear a.c. used to work and now if I turn the a.c. on even if the back is off I get a kinda squeak noise from the back where the core is but no cold air to the back. I checked the lines near the core (and the noise) and one line is cold the other isn't. I'm thinking the core of some sort. Any ideas?

Second part:
I'm sure this is the 4x4 shift motor but want to check. My 4x4 won't work anymore. It was working sporadically then the awd only worked, now nothing. Installed a new a switch and nothing. When I start the truck the lights come on like normal. Ideas?

Last:
The dreaded rear end whine. When I am accelerating it whines like a ****. Let off and it's quieter but still whines. Checked fluid and it's clean. I'm sure it's a bad bearing. Been doing this forever. Only major thing this truck does. So my question is, how hard are these to replace the entire rear end? Truck only has 127k on it.

Long time viewer of the forum so I figured you guys could prolly help me with this thing.

The only other thing I have to do is ball joints.

 

[toms89]

I have a 1998 expedition 4x4 with the 5.4. This is gonna have a few questions so bear with me. First, the rear a.c. used to work and now if I turn the a.c. on even if the back is off I get a kinda squeak noise from the back where the core is but no cold air to the back. I checked the lines near the core (and the noise) and one line is cold the other isn't. I'm thinking the core of some sort. Any ideas?

I would expect the return line as well as the core to be cold. The high pressure side would be warm. No idea on the noise. Does the fan work? Heat work??

Second part:
I'm sure this is the 4x4 shift motor but want to check. My 4x4 won't work anymore. It was working sporadically then the awd only worked, now nothing. Installed a new a switch and nothing. When I start the truck the lights come on like normal. Ideas?

Your 98 has a "center axle disconnect" so I would check it for proper operation as well.

Last:
The dreaded rear end whine. When I am accelerating it whines like a ****. Let off and it's quieter but still whines. Checked fluid and it's clean. I'm sure it's a bad bearing. Been doing this forever. Only major thing this truck does. So my question is, how hard are these to replace the entire rear end? Truck only has 127k on it.

Has the ring and pinion every been swapped out?? Gears can whine pretty well if backlash is set up too tight. I would expect more of a rumble with bad axle or carrier case bearings due to the relatively low speed. Pinion bearings a possiblity.

 

[jsawyer1181]

The fan and heat work fine both front and rear. The only time I get the noise is when the a.c. is on.

 

[jsawyer1181]

What and what's is the center axle disconnect and how do I test it?

 

[jsawyer1181]

I don't know if any work has ever been done on the rear end. I've read that it can be a bad ring and pinion.

 

[tonydiv]

A common problem with the center axle disconnect is the part where the steel shift rod goes through the aluminum axle housing. It gets corroded and the vacuum actuator can't move it to engage the front axle.

The system relies on vacuum to actuate everything, so if there's a leak or one of the vacuum switches (on the firewall behind the battery) is blocked or broken, the front axle wont' engage. You can test this by shifting in to 4x4 and have someone watch the front driveshaft while you do a burnout on some gravel or snow. If the driveshaft spins, and the front tires don't spin too, then the front axle disconnect system is at fault.


If the 4x4 light on the dash won't engage, then it's probably the shift motor.

 

[jsawyer1181]

Yea the switch does nothing at all. The system used to work off and on. The last time I used to the awd position was the only thing that worked. Now it does nothing when u move the switch. No lights, no click, nothing. The only time those lights come on is when I start the truck.

 

[Lightnig]

A common problem with the center axle disconnect is the part where the steel shift rod goes through the aluminum axle housing. It gets corroded and the vacuum actuator can't move it to engage the front axle.

The system relies on vacuum to actuate everything, so if there's a leak or one of the vacuum switches (on the firewall behind the battery) is blocked or broken, the front axle wont' engage. You can test this by shifting in to 4x4 and have someone watch the front driveshaft while you do a burnout on some gravel or snow. If the driveshaft spins, and the front tires don't spin too, then the front axle disconnect system is at fault.


...

I believe I may be having this very issue myself right now on my 97. Anyone have further details for troubleshooting/fixing?

 

[tonydiv]

I ditched the vacuum system for a 4x4PosiLok cable. It's the only way to be completely sure that the center axle disconnect is engaged. http://4x4posi-lok.com/app_ford.html

I was worried that I was going to have to rebuild the front axle housing to make it work, but the fix for the corroded shift rod was actually very easy. I disconnected the vacuum 'motor' from the linkage and sprayed it with WD40 Rust Release spray while I moved the lever back and forth with a pair of vice grips. It loosened up after a few minutes and I never had to tear in to the axle housing to do any further repairs. (this is also a good time to change out the front diff fluid)


If you decide to stay with the vacuum system, those parts aren't very hard to test. A cheap hand vacuum pump from Harbor Freight Tools is really all you need.

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First you need to locate the vacuum solenoids on the firewall, behind the battery. If you disconnect the different hose you can easily test them. The 'input' hose should have vacuum when the truck is running. The 'output' hose should switch based on the 4x4 switch position.

You can test the line going to the vacuum 'motor' on the axle by checking for vacuum when the 4x4 switch is engaged. If that's ok, then you'll want to have the right wheel jacked up off the ground to test the vacuum motor itself. Have someone turn the wheel slowly as you use the hand held vacuum pump to engage the motor. You should see the lever move and feel the center disconnect engage (tire won't want to spin anymore) Oh, remember that there are 2 vac ports on the vacuum motor, one for engage, one for disengage, make sure that you're testing the correct side.

That's kind of a crash course. If you have any other questions once you get in to it, let me know.

 

[jsawyer1181]

I'll take a look at that and see if that's the cause. Thanks, I appreciate that. On the a.c. issue, I believe I'm low on coolant. I filled it before summer and now it needs another can. Tells me I have a leak somewhere. Figures.