I have a 1997 Blazer LT. 4WD. Having problems with 4X4. Read many posts and believe I have Isolated the issue to the front axle not engaging, and founf some issues with the vacuum. The handy post has ruled out the t-case as I can not rotate the front drive shaft when 4 Hi is illuminated and vehicle is running in Park. Went searching and found that the black ball didn't have a hose connected to it. Found the hose plugged with a bolt (bought vehicle used). Nipple on black ball is missing, so there is nothing to hook it up to.

I still have a vacuum when I pull out the bolt, but it does not seem very strong. I can't imagine this would cause it to not work completely as there is vacuum. Do I replace this and then go on, or is it more likely that there is a problem in the vacuum switch on the t-case or the actuator itself?

I'm assuming the reservoir just helps regulate vacuum pressure deviations to some degree.

Thanks

 

Bet there is a leak in the acuator under the battery box. Take it out squeez. air out and plug vacume hole if it leaks out its bad.

 

I would say that you have other problems with the vacuum system on the truck. I would methodically go through and replace all of the vacuum lines to be sure that you do not have a cracked hose somewhere leaking.

As far as the vacuum ball goes, just get a new nipple for it and epoxy it in place. Most autoparts stores have double hose barb splice fittings. Drill the hole out large enough to fit the fitting into the vacuum ball and then slather on the epoxy. Don't worry if you end up covering up the end of the fitting with epoxy. Just take a small drill bit and clean it out after everything has setup.

 

A very large percentage of Front Axle engagement is the actuator under the battery The rubber gets a tear in it so it doesn't hold the vacuum to pull in the cable to the Front Diff.

They sell these ***** for many other vehicles, you probably can buy teh cheapest you can find and mount it beside the ABS crap that's on that fender.

 

New info. Actuator is always pulling on the cable. Even in 2Hi. If I pull the vacuum hose off the actuator the cable moves back.

I also didn't mention that the 2Hi light never goes on. I actually thought this was probably just burned out. The 4Hi light goes on immediately when I push the button and goes off when I push 2HI.

I assume the vacuum switch at the T-case may be causing teh problem for the actuator to always be engaged, so I will look into that.

But why would the axle not just be angaged all of the time if the cable is being pulled. Any help there would be appreciated.

Thanks

 

Others have mentioned problems with the collor inside the front diff. As far a the cable always being pulled there is a switch on top of the trasfercase that is real easy to change. You can pull the bulb out of your switch and get a new one at the parts store to get the light to workin again.

 

Thanks. Been looking around the front axle was trying to see how to actually go in and see if the cable is pulling inside the front axle but I can't figure out what to take apart. I see the 3 bolts that the cable guide is attached to and teh switch that mounts, but when I loosen those it does nothing. I fear the axle needs to be removed to replace the cable??

 

Here is a link from Posi-lok that shows how to install their kit. It has some good illustrations
of how to remove the factory setup. May help you get the cable out.

http://www.4x4posi-lok.com/PDFs/inst_500.pdf

 

Thanks. Got the cable out. Problem appears to be internal to the front axle. The shift fork (I believe that is what the cable is attached to does not move axially, either in or out. Maybe this damage was due to the fact that the system was always being engaged.


I'll search around but wondering if anyone knows whether the right side axle shaft and housing can be removed while in the vehicle. I think this wuld allow me to get access to the shift fork and see if I can figure out what the problem is.

I don't know whether I can disconnect the inner right side CV joint and separate it from the axle shaft so I could then possible slip out the housing and axle/fork.

 

Just some more info on what's going on inside there.

It shows you can remove the CV axle to get it out of your way. It's kind of simple ; The fork pulls a Splined sleeve over a second gear to make them 'one'. Maybe a broken spring that disengages it. Look at this Link.. Arrow down to the bottom of the page. That's the stuff you are looking for
http://www.s10extremist.org/tech_art...front_diff.htm