I recently purchased a 2002 blazer with 302000km it runs solid drives good, but issue I'm having is with 4x4 I push the button you can hear a click and then appears to be in 4x4 I climbed under and tried to spin front drive shaft, and it was engaged in the transfer case, did it in 2 hi and it was free, I looked at the actuator under that battery tray and the cable is free and not seized, but it does absolutely nothing.. i noticed that it is full of some sort of oil, and I'm wondering what the issue could be, I'm new to these vehicles, I noticed on drivers side by fender there was a vac line that isnt connected to anything when I covered it and hit 4x4 the actuator went to engage, could this be my problem I know I need a new actuator as this one is buggered,

this is the vac line i fiund thats hissing
i plan on having it into shop but if it's something i can figure out on my own, that do be great, thanks for any help

 

Off of that white one way valve you should have two lines. One goes to the transfer case switch, and the other goes to a "T" fitting. There one goes to the reservoir in the fender behind the ABS, and the other goes to a connector in a wiring harness that goes to the HVAC Control Module in the cab.
The is all dependent on if you have the three button 4x4 on the dash. If it is the 4 button, maybe someone else can help.
If it is the three button, the problem you have is, the front axle actuator is not pulling on the front axle disconnect in the differential to lock the right front wheel. That is why you have no 4wd. You have already checked the driveshaft to the front axle so the transfer case and encoder motor are working fine.
With this many miles on it, consider replacing all the vacuum lines, transfer case switch, and front axle actuator.
This is if it is a three button 4x4.

Good luck

Bill

 

thank you for your response. yes it is 3 btton 4x4, I did figure out the canister in fender and hooked it back up, up on hooking that back up I noticed that the 4x4 actuator under the battery tray started to move when pushing 4x4, but because I noticed there is a rip on the actuator and it's not able to pull cable far enough, so I will be replacing the actuator and getting my mechanic to do new vacuum lines, as for the oil or atf that is in the actuator its self is that caused buy an old stuck switch? or could it be something bigger , no leaks by the transmission/transfer case, I know there's oil leaking from front if motor appears to be crankshaft seal having that done next week, but other then that fluids seem good, is there anything I'm over looking? thanks you for input

 

That's because the transfer case switch is bad and sucked fluid into it and through all the vacuum lines. The front axle actuator died due to age.

If it were me, I would replace the bad actuator, all the vacuum hoses and the transfer case switch.
Down the road, you are looking at replacing the HVAC Control Module in the dash because it, too, has fluid in it and you're going to have problems controlling the vent positions in the cab. Then last but not least, if it has sucked in alot of fluid, is the vacuum reservoir in the fender.

If you replace all the above and down the road it happens again, the fluid that is in the reservoir is now the cause . It will also cause the vents to work improperly in the cab.
I have never replaced the reservoir, could not find a part number or any way to get at it so when mine went bad (the nipple broke off), I just replaced it with a vacuum ball from a first generation s10 platform and put it next to the distributor. All is now well.

Good luck,,

Bill

 

I will definately do all those things you explained as well as look into the other things,, I appreciate all the input and if I have any other issue I'll be sure to check here for help, thank you,