Front automatic wheel hub issue
 

Hi,,,

I have a question about the front wheel 4x2 hubs... 89 2-door blazer 4.3L

Trying to get this thing running. When I engage the 4 wheel drive the automatic hubs (either one or both) wont lock up.. they click loudly when the car is moving and wont lock... Are these things more trouble than theyre worth to fix, or should I just get new ones? What could be wrong with them? Im not familliar with the internal workings of automatic hubs as I am used to manuals on my Tracker and a true 4x4 on a Dodge Ram pickup..

RE: Front automatic wheel hub issue
 

First of all these do not have "automatic hubs" what you are hearing is the front axles being locked together inside the front differential. The noise you are describing is usually caused by either different sized tires on the truck or 1 or more tires being low on air pressure. If you have 4 matching tires (all the same size and worn evenly with the same pressure) then you could have a problem with the front axle actuator (vacuum diaphram...under the battery tray) or the cable that it pulls to lock the axles together.

RE: Front automatic wheel hub issue
 

The tires are fine... I dont think its that problem, tires wouldnt cause the 4 wheel drive not to function would it?

The vacuum diaphram, Id assume, is that funky ball under the hood... Do you have any tips on how to fix it?

thanks for your help.

RE: Front automatic wheel hub issue
 

I think the first question I should be asking is how does this system work... I have a basic understanding of automobile mechanics, but that vacuum system is totally alien to me.

RE: Front automatic wheel hub issue
 

All the vacuum system does is control what's engaging the 4wd it is a "true 4wd" system as you called it... you're just not usin' a shifter... you're pushin' a button that's opening a solenoid to allow the vacuum to pull a diaphram that is connected to a cable that's doin' what you did with the shifter is all...(SHEEZ say that 3 times FAST).... the hubs are locked in all the time at the wheel and all the way up the axels into the diff you're not out lockin' in hubs and stuff...

RE: Front automatic wheel hub issue
 

ok... it is a shifter not a button on my blazer.. our truck is a shifter as well, but it doenst have one of those balls under the hood...

But Im not sure where to begin to get this thing fixed... Like I said, all it does is click, and I dont feel the power from the front end, (4 wheel is not engaging)

RE: Front automatic wheel hub issue
 

A ball?? you talkin' about the vacuum reserve ball? hangs under the hood and has one vacuum line goin' to it??

RE: Front automatic wheel hub issue
 

Yes... Isnt that the 4 wheel drive thing?

RE: Front automatic wheel hub issue
 

on mine... no... that's the vacuum reserve ball... your 4wd vacuum actuator is under the battery tray... or should I say that's where mine's at

RE: Front automatic wheel hub issue
 

If you have a basic understanding, then you should know the difference between a vacuum storage tank and a vacuum diaphram right?

As I said in my original reply....It is under the battery tray.

When you shift the t-case into any 4wd mode or range...with a lever OR a push button switch......a cam inside the t-case pushes up on a simple vacuum switch (monted on the top of the t-case on the driver's side) which routes engine vacuum to the actuator under the battery tray. The vacuum forces the diaphram to shrink or close and it pulls a cable that is attatched to a sleeve in the front diff. The sleeve slides toward the passenger side and locks the two front output shafts together and violla..4WD And YES TIRES CAN DEFINITELY CAUSE THIS NOT TO WORK!