Alright... new problem. I have the 4 button 4x4 with auto 4x4 on the dash, Np8 transfer case. I have had occasions (a while back) where the 4x4 worked. But all the sudden one day it doesnt. All vaccum lines are hooked up and not dryrotted. The transfer case sounds like it activates to engage 4wd. And it sounds healthy. 4 Low shifts in nice n hard but the front tires dont spin in either 4wd option. I know this transfer case has the clutch in it for the Auto option but I never use it. My question is, could the clutch be what is making the front axle not engage? Or could it be something else? Any troubleshooting help is appreciated.

 

Take a look at the front axle's 4x4 gear actuator, it is what moves the gear in the front diff to engage the front wheels. They go bad sometimes.

 

Even if vacuum lines don't look dry rotted, they can still leak. Until each line is tested with a MityVac or similar, you won't really know for sure.

Like Jsilvr said, the actuator under the battery tray is a common problem. Also, you probably have a vacuum solenoid attached to the firewall under the hood, which opens the flow of vacuum to the actuator. That can sometimes quit working.

 

same problems it sounds like here...subscribed

im assuming you mean the vaccuum actuator under that battery tray, right? i pulled my battery out last night and it seems to be in good shape. start the truck and hit 4wd, either hi or low and the transfer case engages as its supposed to, lights work as normal, vaccuum actuator sucks in, but no front wheels pulling.....any ideas? vaccuum not pulling hard enough maybe? other issues i havent thought of??

 

Is the actuator making the cable move? If so, how much movement do you get?

 

I apprecitate the feedback...

So i did some testing today, The actuator under the battery works fine and holds tight with just using my fingers.

Next test, I had the truck running, I shifted it into 4hi, got under the drivers side and tried spinning the driveshaft. The driveshaft spun 1/4 turn and clunked. back and forth it turned a 1/4 turn and clunked to a stop.

I also checked the vacuum actuator under the battery tray before shifting into 4hi, it was out. after shifting into 4hi and then shutting it off, I went up there and it was still out. That doesnt seem right. It should have moved and stayed in that position even with the engine just shutting off right?

And I am hearing a small clicking noise on the drivers side when moved. It does not change with rpms. Only with wheel speed. Barely noticeable but still its there...

Does that bring up any ideas?

Also i will check the vacuum solenoid on the firewall.

And rntbuck please dont threadjack... Its hard enough trying to figure this out even without someone else blurting in their problems.

 

excuse me....i "thought" that since our problems were very similiar, if not identical, that it would be ok to post in your thread....maybe, just maybe, my input, or someone elses directed toward mine may would also help you out, as i am certainly paying attention to what is said about yours also. i figured it would be pointless to start an almost identical thread right on top of yours. sorry, i didnt realize i was hurting things. to me, thread jacking would have been something more along the lines of.... "my 4wd went out on a recent fishing trip, but let me show you the size of these fish i caught", sorry,certainly didnt mean to cause any harm

 

Our problems are close to the same but not the same. Please just read and post only if you have ideas about MY problems on MY thread. Otherwise i honestly dont care if you post on top of my thread. Back on topic please.

 

wow...didnt mean to hurt your feelings....and i get that YOU dont care about a thread on top of yours thats essentially identical to yours, but im sure there are those that may care..thats all....nbd...i am all ears as to any input anybody has to say, as in my mind our problems are very similiar

 

So back on topic...when you say the actuator under the battery tray was "out", do you mean it was not pulling on the cable? (i.e the diaphragm was still "fat" and not contracted) If the vacuum system is working properly, it will suck in the diaphragm when you shift to 4HI and probably hold that suction for some time (with help from the vacuum reservoir), after you shut off the engine.

Also wasn't sure what you meant by holding tight just using your fingers.