I checked for an vac. actuator as Les M. posted a photo of in his 'Front axle 4WD lock Questions' and couldn't find one. I have the three button version , not four. I checked the glove box ID build card and no NP236.

 

Please note: I do have a steady '2 HI' light.

 

U might be ok as I said earlier, if the truck engages all 3 buttons correctly then just address your issue. Your problem was the noise correct? Just stick with a solution to it and if u never had trouble with the 4x4 then why stress. I still believe if this post was actually meant about the noise at high speed, that your bearings are most likely ur issue

 

I am having trouble posting for some reason. I tried to post earlier that I suspect my 3 button 4WD has the vac. actuator hidden under the battery and batt. holder. For a temp. solution to the vacuum actuator always on , can I just pull a vacuum line and plug it so the 4WD won't be stuck on? Any suggestions? I am scheduled to tow a car dolly tomorrow with the Blazer.

 

Ricco, I appreciate your advice on changing out both wheel hubs. I was hoping the wheel hub/bearing would be a time where you could replace just the one that is defective. I am stressed because today--Wed. 8-26-- I have to move my classic 66 MGB out of storage in an auto shop in a distant city. The shop owner is closing up on 8-31 and moving to Texas. I am heading out shortly to do that. So I am hoping the hub holds up and the 4WD 'locked up' doesn't create any problems to aggravate the hub. I look forward to coming back and fixing the wheel hubs and the 4WD system. Thanks to all for the info. Jim

 

I just reread your post above. I may have given you bad info the first time in saying you have proven your front axle to be locked, and took you down the wrong path. Sorry about that. Sometimes I just need to keep quiet. But here I go again.

Way to check if front axle is locked in (both 3 and 4 button) is to jack up the passenger front wheel only. If the front axle is unlocked, turning this wheel should be easy and not turn the driveshaft going from the transfer case to the front differential.

Way to check if the transfer case itself is stuck in 4WD is to jack up the front end and try to turn the front driveshaft (the shaft from transfer case to front differential). On a 3-button you should easily be able to turn it if it is in 2WD. On NP236 4 button the driveshaft can be difficult to turn, even when in 2WD due to preload. I know that mine is.

You might want to have a read in this tech article. It helps explain things.

https://blazerforum.com/forum/tech-a...4hi-4lo-41226/

p.s if you've been into little British sports cars for a while, do you remember PDLJMPR Web Magazine for the Sprites and Midgets back in 1996 - 1999? That was me.

 

I remember the Bug Eye Sprite and the A-H Sprite and MG Midgets that followed. They looked like a smaller version of the MGB. The B-E Sprite with the tilting forward hood was always a favorite of mine. I do not remember the PDLJMPR web mag.
I have written a long response to this two times and both were lost in cyber space. I hit 'Post Quick Reply' and it would vanish.

 

As a response to your earlier post on removing vacuum line at actuator to make sure no axle lock up, yes you can. To see if your transfer case is in 4hi the front drive shaft will be locked up/not turn while parked. Hope that helps. The front axle cable may have froze up due to rust so check for cable movement while your at the acuator.

 

TMM, when testing the vac. actuator and the bellows and the cable, you of course, have to remove the battery and the battery tray. Can you do the tests with the battery removed? What is the best tests to do for checking the vac. actuator and the bellows?

 

You can test the cable by hand to see if it moves without the engine running. To test with engine running use a jump box to start and check movement between 2hi and 4hi. bellow should be in in 4hi.