4x4 questions

[mkc1962]

New to this forum, but not new to forums or 4 wheel drive vehicles.

I just obtained a new to me 2006 expedition. This is the first 4x4 Ive ever had that has everything automatic. Trying to find a FSM so I can understand all the components of the system.

Correct me if I am wrong. If the 4wd selector is in 2wd. Nothing should turn either on the front end or between front and transfer case? Other than the wheels of course. By making some marks on the front shafts/xfer case shaft it appears something on mine in locked in place. At the moment I have a leaking from differential and I don't really have time to fix it yet, However, I want to drive the truck but dont want to drive it if something is moving that shouldn't be

 

[tonydiv]

Your truck has integrated wheel ends, so when it is in 2wd the front axles, differential and driveshaft should not be turning.

When you put it in to 4wd, vacuum locks the integrated wheel ends and the transfer case motor switches the transfer case in to 4wd and sends power to the front driveshaft.

 

[mkc1962]

Tony, thanks for the quick feedback.

Ok I figured out the front wheels pretty easy and confirmed that they arent engaged. But I still think My xfer to front diff shaft is moving. 2 reasons, I can make a mark on it move the truck and the mark has moved. 2nd, when in 2wd shouldnt I be able to grab my xfer to front diff shaft and rotate it freely by hand? I know that is how my old 4x4 was. Or is there something inside of this auto select that wont let me do that. this thing to me feels engaged.

when in the seat and select Auto4 I here nothing, when I go to 4hi I hear a clicking, to 4lo a clicking and so forth back down but between 2wd and Awd I hear nothing. The lights and the digital display say I am in the proper range but I dont hear any sort of clicking as I do the other changes.

I need to spend some time researching all the forum chatter on these, but didnt I read something about the xfer drive motor (select changer) going out or having problems on many expeditions? At the moment dont really want to drive it if that shaft is moving.

OnLy other thing I know to do is jack up the back end, put in drive and see if that front shaft is rotating.

 

[mkc1962]

well here's and update. I raised the rear wheels and when in drive the front shaft most definately spins.

removed the xfer motor. It appeared to have a home position and two other positions when selected. Moved smoothly and went to each position when told to. I also noticed the xfer case was stamped 2wd, 4hi and 4 lo at the output shaft where the motor mounts. I could also manually select any of these positions manualy by roating the output shaft. Of course even when pointing at 2wd the shaft to the front diff still was bound. My Question is, what makes it stay engaged for Auto4? Is there some sort of solenoid that might have gone bad and has the xfer system engaged....hmmmm.

 

[tonydiv]

The truck should be running when you're doing these tests. You'll get more accurate results.

 

[mindgame]

Ok... Here we go again....

For Gen2 and above..
When the selector is in 2WD. The front xfer and front drive shaft will spin.. This is in the event you are driving at 40mph and need to switch to 4WD on the fly, you do not mess the xfer case. When in 2WD, the vacuum to the front hubs will ALWAYS be engaged, thus unlocking the front hubs so they will always spin freely.

When you place the selector in AWD, again the front xfer/DS will spin. In this mode the vacuum to the hubs will either be able to engage or disengage the front hub actuators. Thus giving you 2WD or 4WD at varying speeds without worrying for the xfercase to be out of sync thus causing different rotations when they are engage...

If you really want to prevent the front xfercase from spinning, please search for the Brown wire mod. This will disable the from xfer case from engaging and you will have true 2wd to where the front xfer/DS will NOT be spinning.

This is by design. Albeit against common logic. Try going 55+ MPH on a straight road and switch from 2WD into 4x4. You will not notice a thing.. That's because, the front xfer/DS are already at the proper speed ready to work at your demand... The only thing that actually changes is the vacuum pressure to the front hub actuators..

Hope this info helps..

 

[mkc1962]

Ok... Here we go again....

Ahhh Geeesh, how many times I've said the same thing on other forums.

Apologies guys, didn't mean to ruffle any feathers. Yep,I've done quite a bit of searching here on the topic as well as the brown wire mod. I guess I never clearly saw the part about the shaft on the 2nd gen being normal to spin all the time.I thought it was just about doing away with the AWD. Seeing as how my front differential had a leak, it made me nervous to think it was normal for the shaft to spin all the time. After looking at the schematic this morning, I clearly see what that mod accomplished.

I've fixed part of that leak (cover) but still have a weeping pinion seal I want to replace so Atleast at the moment feel better about the constant spinning. I guess I can see the thinking behind the soccer mom AWD, but like so many others I think the mod is probably something I'll do. The auto locking hubs are cool to have, but I kinda like the rest of my 4wd setup to be old school.

Thanks for all the input.

 

[mkc1962]

...

 

[mindgame]

Ahhh Geeesh, how many times I've said the same thing on other forums.

No worries, when it comes to this issue, I've tore down my suspension so many times I'm sick of it, but in a good way

In any case... If you need to, and are concern about the front diff spinning because of the pinion seal, you can remove the Drive Shaft and 2 front half-shafts. This will totally isolate the front diff and you can repair it at your convenience. Albeit, you'll will now be full time 2wd...

Remember to Index the front shaft with the flanges on the differential and xfer case (another words, draw a line so that they assemble back into the same holes), and cover the front hub actuators with duct tape to prevent a lot of road cra* from messing with the bearings..

Good luck!

 

[mkc1962]

Well seeing as how I now know its the norm for the thing to spin I wont worry to much about it. I fixed the cover leak the other day which was the bulk of the leaking, now just need to make the time and replace that pinion seal. The outboard passenger seal looks like it might also need some eventual attention, but for now I think I'll just keep an eye on the chunk level occasionally.

As you've done it so many times, correct me if I am wrong. The drive shaft and both half shafts all bolt to the associated drive hubs coming out of the front chunk. If all of those small connecting bolts are removed, there shouldn't be much more to just dropping the entire thing, Correct? Thinking it might be easier to just fully reseal the entire thing on the bench vs on ones back.