Hey all,

I joined this forum because my 4wd doesn't seem to be working right. I searched all the previous posts by TN-150 and couldn't find anything that answered my question. Here goes:

2004 FX4 5.4L Supercab, **** style automatic 4wd shifter

I went to test my 4wd the other day and it doesn't seem to work right. I chained my truck to a tree and pulled against it in 4wd high and low and neither spun the front tires. I can tell my Traction Lok works great, but neither of the front tires even disturbed a leaf. After reading the previous posts about IWEs, I checked the vacuum at both front IWEs and both have vacuum in 2wd and no vacuum in 4 high or low. When I shift from 2wd to 4 high, I hear the transfer case engage, and when I shift from 4 high to 4 low, I don't hear anything. I have one more test to try and that is to chain it up again, shift into 4wd and remove the IWE end of the vacuum hose to force the hubs to engage and see what happens. I'll update with those results.

Thanks for the help in advance!

-Tanner

 

Bump. I could use some help with this as I have 28 days left to catch any problems under warranty. If I missed something in the forum search, I would appreciate a nudge in the right direction.

 

Why are YOU messing with it? Use your warranty, that's what it's for!

 

The warranty is 50/50 so if it isn't broke then I'd rather not pay somebody to look at it. Are the front and rear axles geared in such a way that the rear would spin and the front wouldn't?

 

If 4 wheel drive is engaged then both front and rear should spin. Also I think you should just take it in. Yes it is 50/50 but ur deductible would be a lot cheaper to pay, than if you miss something and your warranty expires. If you have already checked and verified that it isn't working might as well have it looked at. That is just my .02 cents though.

 

Well it seems the 4wd is definitely out. Even on asphalt I can't tell a difference at all between 2wd and 4wd. I called the dealer and told him about it and they'll take a look at it Wednesday. What the heck could be wrong with it? I read all of the forums and it seems like broken IWEs either make grinding noises or only one side goes out. With mine, it's totally quiet and neither side will engage. Transfer case maybe??

 

When my 4wd stopped working several times it could of been something so simple as a $40 part to a whole new hub assembly which is like $100 something. But sense nothing is happening i would first look at your IWE Solenoid. Thats what happened to me once and i found out my 4wd wasnt working after i was stuck. Had to have a Taco pull me out that day. It was embarassing haha

 

But if the vacuum lines have pressure in 2 but not in 4, doesn't that mean the solenoids are working right? Also, I made sure the front driveshaft was spinning when in 4wd and it is, so I think the transfer case is ok.

 

Maybe the solenoids are stuck and therefore not releasing???? Just a thought, but I am not even sure if that is possible.

 

Here's what I learned tinkering last night: the left front IWE has a little vacuum, but not nearly as much as the right side. The left front hub is toast. With the engine off (hubs locked) if I pick up the left front and turn the wheel, the CV axle doesn't budge. If I pick up the right side and turn it by hand, the CV turns with the wheel. Also, if I try to shift on the fly, I can hear the whining of the transfer case engaging, and then a short but solid grind coming from the left front.

In conclusion, the left front hub is destroyed due to a vacuum leak somewhere in the left line, therefore causing the hub not to lock and sending all of the 4wd power to that side, and neither front tire spins. The grinding during ESOF is the left hub trying to engage, but failing because it's torn up. In order to truly fix the problem, the left hub needs to be replaced, and the vacuum leak needs to be repaired.

One other question: does the one solenoid operate both hubs? The right side works fine, but the left side doesn't. Maybe it's just a leak instead of the solenoid being toast. Does anyone have a picture of the post-2007 solenoid with the rain shield on it? I'd like to see if mine has the right one.

 

In answer to your question, yes, one solenoid does operate both IWEs. If you do a search on IWEs, I think you'll find pics of the newer solenoid in some of TN-F150's posts. I'd recommend replacing the solenoid any time you replace an IWE. It's cheap insurance to prevent a bad solenoid taking out a brandy new IWE.

 

...and the hubs themselves are not necessarily bad. The IWEs/actuators are what engage the hubs and are usually all that need to be replaced (in addition to the solenoid). That does not mean there are no vaccum line leaks that might also be at issue. The whole system is fairly simple once you understand it. These threads have just about everything you need to know, with a lot of pictures. You may have already looked at the second, but both get added to occationally.

http://www.ford-trucks.com/forums/83...then-some.html

https://www.f150online.com/forums/20...replacing.html

 

I learned this yesterday reading those threads. It would seem Ford anticipated this problem when designing the system. Fein what I understand, the actuator gear is made of a slightly softer material than the hub gear, thereby preserving the more expensive hub not if, but when the actuator mechanism fails. Kind of disappointing, and you have to admit that it's not exactly a great system. Even a small vacuum leak left untreated will eventually cause a catastrophic failure. I would have hoped they would use something more reliable like hydraulics to operate the hubs.

 

Something to be said about the old school system - manually locked hubs and a floor lever that directly operates the transfer case through linkage. Other than a full-time AWD system with a torque sensing center diff, that's the only kind of 4wd I'd ever own. Then again, I'm a manual tranny and wind up windows kinda person.

 

I heard something about a manual hub conversion made by Warn. Anybody know anything about that?