1st I am still searching these forums so I am trying, but I kust want to tell you whats happening so I can be lead in the right direction.

It a 96 s10 blazer 4.3 l engine
3 button switch .

this just started a few days aga last week all was good.

I presses the 4L button and the switch seemed to work as it has in the past.

i then hear a wine/loud roar for the front and the truck want to come to a stop. 4h does not work either. I tried to go back to 2 wheel drive and the switch seemed to work fine but it remained the same, (loud roar from the front and wanted to stop the truck) .

So I went in reverse and then it went back to 2wd.

And ideas? Tuesday I will remove the battery and check vacumn on the actuator.

right now I am investigating this tread

https://blazerforum.com/forum/tech-articles-diy-29/4x4-no-worky-maybe-will-help-7180/

ok so far when engine is running and switch is 2h front shaft turns, 4h and 4l the shaft does not turn by hand.



OK I tested the actuator - removed the cable from it, pressed plunger in and put my finger over the vacuum side hole and the plunger remained in till I removed my finger from the vacuum .


I used a pair of vise grips and pulled the cable and it did not come easy. I put wd40 in it and worked it back and forth. I was able to pull the cable about 1/4 of and inch (not much).. So I thought the cable could be bad ! but just last month it worked fine.


Now where the cable goes to the front axle it is connected with 2 bolts (if I remember correctly) can I remove the bolts and remove the cable ? and how is the cable linked to what ever is is attached to inside the axle??\\

Any thoughts have pease

if the front axle was low of fluid will this cause the noise and the truck wanting to slow down ?


If i=I removed the vacuum hose from the actuator and started the engine then put my finger over the vacuum hose will I fee a lot of vacuum? I want to see want to see if the vacuum system is working correctly.

 

ideas

 

All of what I am about to say has been covered in quite a number of threads already.

You should get somewhere around 1/2" of travel on the cable.

You should see close to engine vacuum at the actuator. A vacuum gauge is the only real way to know what you have there. There should only be vacuum at the actuator in 4HI and 4LO, not while in 2HI.

Your problem sounds like the cable is not moving properly and has partially engaged the collar in the front axle. The cable just has a little spring clip on it under the cover on the front axle. It is quite easy to remove. You will then need to make sure that the shift fork in the front axle moves in and out. It will have a spring to pull it back in which disengages the front axle. If it does not return, then the spring is broken and could be complicating our problem.

 

are you trying to put the truck in 4wl while it is moving? that could be the reason why u here a ROAR from the front to go into 4wl you need to be parked cheif!

 

What should the engine vacuum psi be?? I have a hand gauge to check it with..


I just don't see any pics on what the front collar looks like inside, Or the shift fork I will remove the cable and see if that is sticking or if the spring is broke.

if you know of any pics please let me know.

 

CLICK HERE There is a wealth of information in old posts.

 

I caint find what the psi from the actuator should be.

 

Since every engine has different vacuum levels at idle, you really need to compare your direct engine vacuum with what you are seeing at the actuator. So connect your vacuum gauge to a manifold vacuum source and record the reading then reconnect whatever you disconnected to take the reading. Then measure the vacuum at the actuator with the transfer case in 2HI (reading should be zero). Finally, measure the vacuum at the actuator in both 4HI and 4LO (reading should be close to that measured at the intake.

Reference threads with a quick search (search terms "+manifold +vacuum") :
Actuator under the Battery
Front axle noise!

 

Okay checking all the components to the 4x4 unit it is now fixed. Never in my wildest dreams did I believe replacing the 4 tires would fix the problem. It works perfect now!

Thank you to all that helped .

 

Glad to have helped!