Transfer Case Issue?
02-09-2011
#1
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Join Date: Jan 2011
Location: Calgary Alberta
Posts: 119
Transfer Case Issue?
Well, time to ask my first tech question. Anyways a few weeks back when I put the truck into 4H I waited a bit as usual before giving her some gas and when I did I heard a kind of a thunk like something was being forced into gear and I didn't really get any traction. This happened a couple of times and then it stopped happening. Tonight when I was out in the snow, I put it into 4H and noticed that the rear was swinging out on me which has never happened when it is in 4WD. This got me thinking that it wasn't really in 4WD and I noticed that the steering didn't feel like the front axle was engaged. So I'm thinking that for some reason the transfer case is not engaging. Does anyone have any ideas? Could it be a servo? Something worse?
To be honest I'm not really sure how these transfer cases work. Most of my experience is driving the older manual style where you manually shifted it into gear. I assume they basically work the same way except they use servos to do the shifting. Any help or advice is greatly appreciated.
To be honest I'm not really sure how these transfer cases work. Most of my experience is driving the older manual style where you manually shifted it into gear. I assume they basically work the same way except they use servos to do the shifting. Any help or advice is greatly appreciated.
02-10-2011
#2
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Join Date: Jan 2011
Location: Oregon
Posts: 239
I really wish there was an option for manual transfer case with manual hubs. I hate the 4x4 system on the truck.
Your transfer case is probably engaging just fine though. Likely, the problem is with the automatic vacuum actuated hubs or wheel ends.
When you turn the **** to 4x4, several things happen. An electromagnet (I believe) spins the front output shaft on the transfer case up to a speed matching the rear output shaft, then engages 4x4 when the speeds are equal. When that happens, a vacuum solenoid (IWE solenoid) on the firewall (behind the battery) stops applying vacuum to the integrated wheel ends (IWE). With no vacuum applied to the integrated wheel ends, a gear locks the hubs to the axleshaft.
So you can see there are many things to fail. If the 4x4 light comes on the transfer case should be engaged. The transfer case will not engage if there is not electrical power to the IWE solenoid on the firewall (at least mine doesn't). So assuming that 4x4 light is on, you probably have either a vacuum leak, a bad IWE solenoid, or a bad IWE. It could even be something as simple as water in the vacuum lines that has frozen and prevent vacuum from being applied to the IWE.
Due to the placement of the solenoid, when it rains, water can drip down from the firewall onto the solenoid. Ford released an updated solenoid with a little plastic hood to keep water off. See this thread for part numbers.
For reference, the auto hubs are LOCKED when vacuum is not applied. When the truck is off even in 2wd, you should NOT be able to turn the front axleshafts by hand. When you start the truck, they should unlock as vacuum is applied. You could start by confirming that this is happening.
When the truck is off, crawl under the front of the truck and verify that you can NOT turn either of the front CV joints by hand. Start the truck, crawl under and confirm that you can turn both by hand now. Turn the **** to 4x4, and confirm that they are again locked. Also keep in mind that, if one is locked, it will be tough (maybe impossible) to turn the other shaft. It might be easier to test with the front tires off the ground.
I hope that makes some sort of sense. It's late and I'm tired so it may not. lol
The hubs on my truck have been a little strange too. Although mine seems to have an intermittent problem where it stays engaged in 4x4 for a period of time, after shifting to 2wd. I guess that is the better problem to have, but still frustrating! I replaced the IWE solenoid and it seems to be less frequent, but it can still be stubborn when disengaging 4x4 when it's really cold for some reason.
Your transfer case is probably engaging just fine though. Likely, the problem is with the automatic vacuum actuated hubs or wheel ends.
When you turn the **** to 4x4, several things happen. An electromagnet (I believe) spins the front output shaft on the transfer case up to a speed matching the rear output shaft, then engages 4x4 when the speeds are equal. When that happens, a vacuum solenoid (IWE solenoid) on the firewall (behind the battery) stops applying vacuum to the integrated wheel ends (IWE). With no vacuum applied to the integrated wheel ends, a gear locks the hubs to the axleshaft.
So you can see there are many things to fail. If the 4x4 light comes on the transfer case should be engaged. The transfer case will not engage if there is not electrical power to the IWE solenoid on the firewall (at least mine doesn't). So assuming that 4x4 light is on, you probably have either a vacuum leak, a bad IWE solenoid, or a bad IWE. It could even be something as simple as water in the vacuum lines that has frozen and prevent vacuum from being applied to the IWE.
Due to the placement of the solenoid, when it rains, water can drip down from the firewall onto the solenoid. Ford released an updated solenoid with a little plastic hood to keep water off. See this thread for part numbers.
For reference, the auto hubs are LOCKED when vacuum is not applied. When the truck is off even in 2wd, you should NOT be able to turn the front axleshafts by hand. When you start the truck, they should unlock as vacuum is applied. You could start by confirming that this is happening.
When the truck is off, crawl under the front of the truck and verify that you can NOT turn either of the front CV joints by hand. Start the truck, crawl under and confirm that you can turn both by hand now. Turn the **** to 4x4, and confirm that they are again locked. Also keep in mind that, if one is locked, it will be tough (maybe impossible) to turn the other shaft. It might be easier to test with the front tires off the ground.
I hope that makes some sort of sense. It's late and I'm tired so it may not. lol
The hubs on my truck have been a little strange too. Although mine seems to have an intermittent problem where it stays engaged in 4x4 for a period of time, after shifting to 2wd. I guess that is the better problem to have, but still frustrating! I replaced the IWE solenoid and it seems to be less frequent, but it can still be stubborn when disengaging 4x4 when it's really cold for some reason.
02-10-2011
#3
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Join Date: Jan 2011
Location: Sheboygan WI
Posts: 459
Have you had your truck scanned for any codes? Some codes do trip a check engine light. That may help narrow down where to look. Could you tell about where the thunk came from? Was it in front or more centered on the truck? I would tend to lean more towards the hubs being the problem then the transfer case.
02-12-2011
#7
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Join Date: Jan 2011
Location: Calgary Alberta
Posts: 119
OK, so I was able to crawl under the truck today and if I understand Brian's explanation correctly, my issue lies with the driver's side IWE. When the truck is running and in 2WD, I can turn the CV joint on the passenger side but, not on the driver's side. When the truck is off or in 4WD I can't turn either of them. In your informed opinions would this be more indicative of a failure of the IWE or is it possible that it is just the vacuum line to that IWE? I think I still need to think this through to understand what's happening, but any comments or suggestions are welcome.
02-12-2011
#8
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Join Date: Jan 2011
Location: Oregon
Posts: 239
Have you had any noise from the front end in 2wd? Buzzing, whirring, something like that?
It sounds like that driver's side isn't disengaging, but I wonder why. It sounds like they are both engaging though...?
I guess the smart thing to do would be to look up a manual for diagnosing the vacuum setup. Typically I try to narrow something down and replace what I think it is, but sometimes that cost more money and aggravation. lol. So I hate to direct you to replace something that it may not be. I'll see if I can find some diagnosis stuff.
It sounds like that driver's side isn't disengaging, but I wonder why. It sounds like they are both engaging though...?
I guess the smart thing to do would be to look up a manual for diagnosing the vacuum setup. Typically I try to narrow something down and replace what I think it is, but sometimes that cost more money and aggravation. lol. So I hate to direct you to replace something that it may not be. I'll see if I can find some diagnosis stuff.
02-12-2011
#9
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Join Date: Jan 2011
Location: Calgary Alberta
Posts: 119
No noise. I agree it sounds like the drivers side is not disengaging. Which is kind of weird because as I said in my op when I turn, it doesn't feel like the half shafts are engaged at all. I have a Ford DVD with the factory repair manual so I've had a look at it. Tomorrow I will take my code reader out and see if any codes pop up and if so compare them to ones in the shop manual. If no codes pop, I'll have to think of something else.
02-12-2011
#10
Senior Member
Join Date: Jan 2011
Location: Oregon
Posts: 239
Hmm. Often times they only partially disengage and the gears grind up in the wheel end causing the noise in 2wd.
However mine have been a little finicky the last couple months similar to yours. Originally I thought that maybe I had water in the vacuum lines that froze, but I don't know. Just a random guess on my part. I replaced the solenoid with the new part with a hood, but still don't really know if it that's the issue. Lately it has been working as it should.
However mine have been a little finicky the last couple months similar to yours. Originally I thought that maybe I had water in the vacuum lines that froze, but I don't know. Just a random guess on my part. I replaced the solenoid with the new part with a hood, but still don't really know if it that's the issue. Lately it has been working as it should.