So lately ive been trying to get my 4wd to work and no luck. For the longest time 4lo would blink and blink and go back to 2wd. Well today 4hi and 4lo both seem to lock in but front tires wont spin and i get a horrible grinding/vibrating noise when in drive. If im in 2wd no noise while in drive, only happens in 4hi or 4lo. Could it be something binding up? If so whete should i start looking at. Any help would be much appriciated. 95 blazer 4.3l!

 

Possibly a bad 4wd actuator. I had the same problem on my 97 after the oil lines leaked over the top of it. They are vacuum operated so if oil or dirt gets in them they bind up and the 4x4 will not fully engage/disengage causing a vibrating/grinding noise.

 

Would a possible bad u joint cause this issue? Never had 4wd in my life. I unhooked the 4wd cable and pulled on it by hand. Thats why im confused.

 

So an update, hit my 4hi got out pulled on the cable by hand and nothing, so i thought what if i sping the front right tire while i pull on it and bam its locked in. What would cause this to happen? Thanks in advance.

 

There should be an air reservoir right in back of your battery, Follow the air lines. One set should Tee off under your battery. Check those lines for leaks. Perform a direct vacuum to the lines under your battery and see if Engage and Disengage work as you apply the vacuum.

 

Memory Dump, However, I am pretty sure that 4 Drive is disengaged when vacuum is present. Therefore try to Remove the vacuum to disengage and apply vacuum to engage. Keep this in mind while you are trying things. On these Blazers they need to be in motion to engage and disengage. So you will have to move the vehicle while performing tests.
Another thing to remember is that a 4x drive is there for slippery surfaces. Dirt, Mud, Snow etc. If you are attempting to engage on Tar or concrete you are going to have a hell of a time. While these systems are I fact engaged on Tar they will sound like your front end is going to blow up.
If you are trying this hard surface there may not be anything wrong. Suggest you put it in dirt and remember it has to be in motion to disengage.
Good Luck

 

Finally got the 4wd to work! Thank you guys! Came across a new issue, noticed when i was changing the acuator under the battery my vacuum line had ATF fluid in it. Did some reading sounds like a tcase input seal. Figuered i might as well pull it and do all seals and a new vacuum switch. Now can i pull the tcase or does the transmission have to come out also?! Thank you in advance.

 

No on removing tranny. I have removed several over the years. If you are working on the ground or concrete and want some detailed instructions let me know.

 

That would be very helpful!

 

I am not recommending this to you or anyone else. Having said that I have always removed all my tyrannies by raising them up and supporting things well then actually get myself right under the tranny and pull them out. It rests on my chest as I slide to right and place it on the ground. I used the same method on about ten transfer case removals. The Torsion Bar Support is used to rest the transfer case tail shaft on then lower it down. Do even think about it till you go see if you can control that kind of weight. Drain all the oil first. I would advise you get a tranny jack myself. As I got older I made an attachment that goes on my floor jack and strap em down now.