On my 2000 F350 with the 4 X 4 switch on dash. How can you be sure the 4X4 works. Playing with it in my driveway I could here it click sometimes and clunk when I put it in low. And it was geared lower. But the other day when I was stuck in the mud the light would come on but never heard a click and front axle never engaged to pull me out either. Played with it again the next day and it seemed to activate in my driveway again. How do I know for sure without getting stuck again? Thanks in advance for any advice. Hopefully I can return a favor soon.

Merry Christmas to all

 

There are a bunch of things you can do. The simplest is put it in 4WD and drive it slowly, turning sharply. In a turn the front wheels need to go farther than the rear. 4WD won't let them, so you'll probably be spinning a back tire (usually the inside one). If you're on a hard surface you'll feel a pretty severe crow-hop as it does this (also can be kind of severe on the driveline, not recommended you do this much). If you're on a slippery surface you might not feel it, but an observer should be able to see it.

Or try spinning the front driveshaft with it parked and in 4WD. If it turns, you're not in 4WD. If it doesn't, either the t.case is really going into 4WD, the hubs are locked, or both (you need both to be really "in" 4WD).

If you do the driveshaft method, then jack up one front tire and try to turn the front drive shaft. If it doesn't turn the t.case is in 4WD, if it does the t.case is still in 2WD.

And if it turns, look at the front wheel that's jacked up. If it turns you're hubs are locked (which is good if you're trying to be in 4WD). If it doesn't turn at least one hub isn't locked.

If the driveshaft doesn't turn (in 4WD with one front tire jacked up), then try to spin the tire that's in the air. It shouldn't turn. If it does you don't have both hubs locked.

By the way, I've been talking about locked hubs as if you know what I'm talking about. If you're new to 4WD and don't know what I'm talking about, that's OK, we all learned once. In addition to shifting the transfer case into 4WD (turning the dial on the dash of your truck) you also need to lock the hubs at the end of each axle. Sometimes that needs to be done by hand, getting out and turning the dial in the center of each front wheel to where it points to "lock" (or something to that effect). But a lot of trucks have automatic hubs, especially trucks that have electronic shift transfer cases.

I think the automatic hubs that were available on the 2000 F-350 are the same ones I had on my '02 F-350. They have the dial on them so you can lock them by hand, but they also lock automatically by vacuum when you shift into 4WD. All automatic hubs seem to be at least a little finnicky. The ones on my '02 had long ago stuck so they were always locked. Always locked isn't so bad, it just means you're wearing things out a little faster and burning a little more fuel when you drive in 2WD. But if they fail so they never lock, then you have a 2WD truck. And they BOTH need to lock in order to have 4WD work.

By the way, the "clunk" you hear and the lower-geared feel you feel when you shift into 4-low is because the transfer case is in low range. If the hubs aren't locked (or if there's something broken in the transfer case so the front driveshaft isn't being driven) you are still in 2WD. You probably won't hear any clunk when shifting into 4-high, and you won't feel anything different either, other than the hopping when making a turn as I described earlier.

 

Hey thanks

 

X2 on what he said about lock in/outs, but do not put it in 4wd on pavement or any other real hard packed surface like pavement.

Great way to break something that is truck and expensive related in the front end. Also can cause a "bind" in the driveline making it very difficult to get it out of 4wd.

 

Tires don't get good enough traction to break anything that quickly. If you drive slow it will wind up then pop a tire free. As I said in my first post, it's not something you want to subject your driveline to much, because it ain't nice on the truck. But it's not going to break it the first, or second, or thousandth time you take a slow corner on pavement.

 

whenever someone asks me how to test their 4 wheel drive to see if it works, i tell them to park the trucks on grass, sand, or mud. put it in 4 wheel and stand on the throttle. if only the rears spin, the 4 wheel is not working.

to figure out where the problem is,
chock hte rear tires front and back.
jack the front end of the truck off the ground.
put it in 4 wheel drive and lock the hubs.. engine shut off.
then get under the truck and spin the driveshaft. if it turns, the problem is in the t-case.
if it does not turn the t-case is good.
spin the passenger side wheel and look at the axle.. if it does not spin, the problem is in the locking hub. if it spins, the passenger side is good.
turn the driver side wheel. if the axle does not spin, it is in the hub. if it does spin, the driver side is good.
if all tests so far pass as good,
now put the transmission in neutral.
spin the driveshaft and see if one or both the front axles and tires turn.
if they do the front differential is good.
if the driveshaft spins and the axles and tires do not, the problem is in the front differential.