Everything in the driveline seems to be OK. However, when I go to engage 4x4, driving along at slow speed, gently pull back on the lever, there is a terrible grinding and gnashing of gears and finally a big clunk as it goes into 4x4.

Once it is in 4x4, it works fine. No abnormal noise. Works good in 4 Low ( of course engaging only when stopped ). Comes out of 4x4 OK too.

Anybody have any ideas here? I do have extended warranty on the old girl. Maybe there's some kind of adjustment? Thanks...

 

Sounds like the clutch inside the transfer case isn't synchronizing the front output shaft to the rear before the gears engage... there is an electric relay and an electric clutch that is supposed to accomplish this feat before engaging the gears... sounds like something isn't working right. I'll look into it a little more when I get home this evening... I need to find out what actually triggers it on the manual t-cases....

-Joe-

Oh, and in the mean-time, I wouldn't try to shift on the fly. If you stop before engaging it, it should work OK.

One more thing... check to see if your front center axle disconnect is engaging... if it is, then great. If not, could be an electrical problem...

-Joe

 

Well, the loud clunking noise is gone!!

But the thing won't go into 4x4 at all now. Neither hi nor low range. The little indicator lights still come on though.

What did I break? Anybody??

 

I was wondering what happened to this thread.....

could be a whole host of electrical stuff.... there's about 60 different tests for it in the shop manual... sounds like an electrical problem at first, but now it sounds like the shifter motor might be turning, but not engaging anything in the transfer case.... as much as I hate to admit it, it's over my head... might be time to take it to a shop... sorry I can;t be more help.

How can you tell it's not engaging?

Let us know what you find!

-Joe-

 

I know it won't go into 4x4 because I went into a gravel pit and tried to climb a dirt hill with the 4x4 engaged, but the rear wheels just spun out. I guess I'll take it into the shop and get a professional opinion. I'll keep you posted.

 

Did you check the center axle disconect? actually, the thing to check ould be to see if the front driveshaft is turning or not when 4wd is engaged. If the CAD is not engaging, the ouput from that side ill spin freely and you will not have 4wd. the actuator for the CAD is on the firewall (driver's side, I think) and looks like a small fluid reservoir, but has a bunch of vacuum lines and wires going to it. If this fails to engage the front axle, you won;t have 4wd.

It's a common failure item on our trucks... it's probably the weakest link in the system... a nice feature, but prone to failure.

Let us know...

-Joe-

 

Thank you for your help, GIJoeCam. When you say that it may be the CAD that may be the culprit, would that account for the bad grinding noise before the system died for good?
If I can find the actuator, how will I know if it is broken. Could this be the cause of a sudden Check engine light I got this morning. A vacum leak maybe? Truck is running fine.

The common failure point. Is it the CAD or the actuator? Thanks a million...

 

hmmmm could all be related, but it sounds like it could all be coming from the GEM module... all the stuff you are describing gets funneled through the GEM...

As for the CAD causing the griding... the only time it would grind is when it's in the process of engaging, and the rear wheels are slipping. I managed to do this out at the sand dunes this weekend... I clicked it into 4 hi, the light came on, and I goosed it... didn't wait long enough for the disconnect to engage and it made a hellacious ker-clunk! But what you described before sounded like the t-case not synchronizing... sounds like something may have let loose in there now... don;t really know for sure, though....

From my understanding, it's the vacuum switch up top that usually fails, or the vacuum lines going to it. I suppose it's possible one of them dry-rotted and cracked..... can;t say for sure, though...

-Joe-

 

Thanks Joe. I'm going to poke around a bit but will probably just get it into the shop for diagnosis. I'll let you know what it is--Jack.

 

I have a manual shift 4 wheel drive and when I bought the truck they told me I could shift on the fly and I did. It seemed to work fine. When shifting to 4 wheel at low speeds I started hearing gears rattling and then a clunk when the 4 wheel would engage. I asked the dealership about this and they told me that if you have a manual shift 4x4 you must be stopped to shift into 4 wheel. I don't know how much truth there is to this but I just deal with it now. I have had to replace the Ford stock automatic hubs twice and have not gone to manual warn hubs so I have to stop anyways.

Salesmen will tell you anything to get you to buy a truck so he might have just said "ya you can shift on the fly" without really knowing.