For some reason lately, my 4WD only works when it feels like it. I needed it today and it wasnt engaging in the front. When I put it in 4 low I could feel it in the rear end but the front wasnt spinning and i almost got stuck

What should I check on this, any ideas?

 

check your vaccum lines from the central disconnect to the t-case and back to the vaccum pump, or check the central disconnect for dammage. thats the best place to start.

 

other things... check the shift linkage, it might have slipped, does the front drive shaft turn when the rear wheels are and the fronts are not? does it work in 4 hi?

 

I'll check it today. Ya I had a friend look under and he said it was spinning it, but the front tires wern't moving. And ya i tried 4 hi, didnt work either

 

Does your 4WD light come on? If mot your front axle isn't engaging.

Check for a vacuum leak. If your CC doesn't work and HVAC is on defrost vacuum loss is the culprit. Look for a broken line or disconnected line.

You say you have 4x4 sometimes so that may not be it. There is a vacuum valve on top of the transfer case that switches vacuum to the CAD system on the front axle. When you shift into 4x4 it routes the vacuum from one side of the diaphragm to the other on the vacuum motor on the front axle to lock the two halves of the right axle.

If the vacuum valve is not working properly the front axle won't engage, your 4WD light won't come on and you will have no power to the front wheels even though your front drive shaft is spinning.

Look at this thread: https://www.dieseltruckresource.com/...d.php?t=198399 This guy had the same problem so he went to a home brew system that gives him full control of front axle engagement. I am going to do the same thing. The other added benefit is you can have 2wd low.

HTH

 

Sometimes this helps Diagnosing 4WD Engagement Problems

 

alright thanks.

I'll be sure to check these out.

thanks guys