Help! 4 wheel drive engages without pushing a button.

[lilmike2]

i have a 1994 ford explorer xlt.. 50000 miles original owner.. the 4 wheel drive seems to activate itself while im driveing especially when makeing turns.. its push button automatic.. the trasmission place says its the auto hubs..they can change to manuel ones.. i dont mind .. ist it the hubs?? any help appreaciated!!!!! i hear whineing and then a clunking.. then it goes away.. if i activate the 4 wheel drive it stops immediatly!!! the noise...

 

[Joey P]

Are the lights on the push button lighting up when it does this? If they are not, I would be inclined to think the hubs are done also. Manual hubs are the way to go BTW, if you don't mind getting out and locking them in for 4wd.

 

[lilmike2]

lights on buttons 1994 4 wheel problem

thanx joey.. the ligts are not comeing on when this happens.. also it did this 2 times last year when it was cold out... never in the summer.. do you have any other suggestions??? any body else can help me out???

 

[fixxxer]

Take the wheel off and inspect the hubs, see if they are packed with grease or if there are any broken parts. the auto-hubs should be only lightly lubricated to protect them from moisture. A heavy grease will keep your hubs from working properly and can cause the hubs to engage and disengage on their own, especially going around turns and in cold weather the grease will stiffen and cause even more issues.

 

[Sams01XplrSprt]

welcome

 

[BrooklynBay]

Welcome to this forum! I've moved your thread to the stock 91-94 section. It sounds like it could be the auto hubs.

 

[EskimoEddie]

Arrrggg, it's too d*mn cold to work on my EX!

Yesterday PM my front wheels started chirping and whining and I haven't used 4wd for about a week and the auto hubs had trouble disengaging then. From all the great posts and helpful replies, I know now that I need to clean & inspect my auto hubs. But to get to the point, would a bad/worn bump stop in the shift motor, causing a PARTIAL engagement of 4Hi and spinning front axle, thereby trying to lock the front hubs? If the shift motor is ok and I want to check that the t-case is not in 4Hi, the front axle shaft should turn freely, correct? If it doesn't spin, I'll know for sure I have overly greased my hubs and they're not disengaging properly. I've noticed that the front end is pulling to passenger side, would this be a hub still locked but t-case in 2Hi? Can I disable the auto hubs easily so I can get my EX to a friend's garage to work on it? Sorry for a long post, but I'm hoping for some tips and TIA, Greg (eskimoeddie)

 

[MrShorty]

But to get to the point, would a bad/worn bump stop in the shift motor, causing a PARTIAL engagement of 4Hi and spinning front axle, thereby trying to lock the front hubs?

It's hard to say that something like this is absolutely impossible. However, this would be the first time I've seen it described, if it is indeed real. I haven't had my shift motor off, but from pictures I've seen, it seems that the detents between 2H and 4H are far enough apart, that I don't see it being very likely that the motor being a little out of alignment would cause the t-case to "partially" engage. Without any more information or diagnosis, I'd blame this all on your auto hubs.

As for disabling, the only way I know of to disable the auto hubs is to remove the outer hub, remove the inner "cam" assembly, then reinstall the outer hub. In some ways, that's half the job of replacing the hubs, so if you had the parts, you could just install new hubs, and not have to worry about moving to a friend's garage. One thing I might try would be kind of the opposite: engage 4H briefly (just long enough to get the hubs to lock), then drive in 2H with the hubs locked. That will usually get rid of the noises and pulling that are associated with "unpredictable" engagement.

 

[HahnsB2]

Sounds like the auto hubs, I had one that would engage and disengage every 3 seconds as you were driving down the road, I gutted the POS's till my manual hubs arrived.

 

[Joey P]

A heavy grease will keep your hubs from working properly and can cause the hubs to engage and disengage on their own, especially going around turns and in cold weather the grease will stiffen and cause even more issues.

also it did this 2 times last year when it was cold out... never in the summer..

I think your answer maybe in Fixxxer's post.

 

[mikeinri]

Stop the madness!!! The problem is the GREASE, not the auto hubs...

Until you abuse auto hubs, there's no reason for them to fail. Abuse includes driving around with them engaging and disengaging themselves because of... wait for it... too much grease!

There are lots of threads here about this. Clean them well (make sure the internal spring mechanism moves in and out correctly), lube with ATF, drain them well and put them back in. Clean all the extra grease off of the spindle and cam assembly, reinstall and you're done.

The hardest part of this will be getting all the old grease out if they're really loaded up. I've used carb cleaner, brake cleaner, toothbrush, etc. for the cleaning. Always follow up with ATF.

Unless you've done a bunch of hard offroading, or driven the hubs this way for a very long time, they're most likely just fine (i.e. you don't need manuals or to replace them with new autos). Just be sure to inspect the teeth, rings, etc. and look for anything that looks broken, cracked or excessively worn.

Mike

 

[montana_joe]

I think Mike nailed it. Start there.

 

[b_train_98]

Hubs?

I have the same problem. I will clean them up and use some ATF when the weather gets a little warmer.
Just out of curiosity, why is everyone so hell-bent on converting to manual hubs? If I get stuck in a snow bank, I'd rather not have to dig myself out just to lock the hubs, knowing that a simple push of a button can do it for me and get me out, especially at -30c!

 

[HahnsB2]

I have the same problem. I will clean them up and use some ATF when the weather gets a little warmer.
Just out of curiosity, why is everyone so hell-bent on converting to manual hubs? If I get stuck in a snow bank, I'd rather not have to dig myself out just to lock the hubs, knowing that a simple push of a button can do it for me and get me out, especially at -30c!

Because manual hubs actually work and are much stronger, same reason I dont have A4LDs either... Imagine getting stuck in that snow bank with broken auto hubs (which is not a far stretch, I bought my sploder a couple weeks after the PO broke the auto hubs in the recent snow storm, and many more were on craigslist with broken hubs after the storm), but at least you don't have to get out of your rig for 30 seconds You can drive around with the manual hubs locked in, I do it any time there is snow on the ground, just engage 4wd when you need it

 

[troy11556]

sounds like it is time to replace the auto hub's with manual. only reson manual they are stronger and cheaper than getting the auto.

 

[b_train_98]

???

If you can run manual hubs with them lock in all the time, then why does automatic hubs even exist? Manual hubs, cheaper, stronger, reliable, doesn't make sense to have autos at all.

 

[DeRocha]

If you can run manual hubs with them lock in all the time, then why does automatic hubs even exist? Manual hubs, cheaper, stronger, reliable, doesn't make sense to have autos at all.

When the HUBs are locked you lose 1-2 mpg on fuel economy due to the additional drag of the front driveline moving. As such having the ability to lock them (autos or manual) helps raise fuel economy ratings. Autos are a selling point for many people that do not understand fully how 4x4 works. As such they press a button and magically they are in 4x4.. Of course as their vehicle gets old and problems creep in they find the cost of such a convenience can be Steep. That is why many people prefer a manual 4x4 shift lever and manual hubs as they offer superior reliability over their automatic counterparts.

also: From the 4x4 troubleshooting sticky thread.

4x4 not working (91-94)
More on Automatic HUB engagement:
When you engage 4x4 the front drive shaft will spin and send power to the diff and then to the axle shafts.. The axle shafts will begin rotating within each autohub; after a few revolutions the engagement cam will have idle up within the autohub and caused the autohub to lock. Once this occurs on both hubs the wheel with the least traction will get power and begin to rotate.

:scratch: Let the above sink in for a minute.. If you try to free a vehicle by quickly going from Forward to reverse you can easily blow an auto hub.. When you reverse direction the axle shaft obviously spins in the opposite direction causing the auto hub to UNLOCK and then LOCK in the new direction.. Under low power this isn't a big deal, but if you're on the gas heavy it can definitely damage the hub... Manual hubs are either locked or open, as such they are unaffected by rocking a vehicle in the manor above.

 

[b_train_98]

Totally tubular!

I obviously didn't know much about the 4x4 system, until now. It all makes sense. I'll probably end up converting later on, hopefully a little maintenance will keep me going for awhile. Thanks for the info.

 

[HahnsB2]

If you can run manual hubs with them lock in all the time, then why does automatic hubs even exist? Manual hubs, cheaper, stronger, reliable, doesn't make sense to have autos at all.

Just because you can run around with them locked in doesn't mean you should all the time, unlocking them can save some wear and tear on the u-joints, mileage of having them locked in isn't a factor when you're running around in snow anyways and i never noticed a difference with them locked in in good weather either.