How can I test my front diff. to see if it is locking in or not. What I mean is If I manually pull the cable, how can I tell if it is in fact locking in or not? Thanks

1996 4 door blazer

 

With jackstands:
put the truck on jack stands, kick it in 4wd, watch the front wheels

Without jackstands:
go out to some gravel road or sandy pit, kick it into 4wd, apply parking brake, punch it.

 

I know that sounds likea dumb question. I'm trying to figure out if its the splines on the driveshaft, the cv joints in the frontaxle, or the engagement pin. I have also heardof a thrust washer going out in the front diff of these vehicles. Anyone know aboutthis?

 

I know about it but if your front diff. goes in, stays in basically you're ok. Sometimes when the thrust washer job needs to be done there is a certain pre-noise but again if it goes and stays in...this is not your issue. JP PS if it doesn't go in or slips out.....now this changes things.

 

It does not go in, when engaged and driven, it sounds like... well what it sounds like is atire rubbing on a fender ( i know that is not the case) I guess I should adjust my origina l question. I am trying to diagnose the problem (splines on drive shaft, cv joints, pin locking mechanism, or thrust washer), the diff is not locking in. I guess I need to just tear into it.[:@]

 

You have to first verify that the vacuum actuator is working properly and getting enough vacuum. The actuator is beneath the battery tray. What usually happens is that either you get a vacumm leak and the actuator does not fully engage, or the cable rusts/sticks and does not fully engage. This half in/half out status at the differential gives a clicking/grinding noise. I'd worry about the cable and the actuator long before tearing into the front diff and checking CVs and axle splines.

 

The actuator works, I have bypassed it by pulling the cable with vise grips. How far should the cable pull? Mine is pulling about 1/2 inch. When driven, and the cable pulled, it is not engaging. That would be nice if its just the cable.

 

The cable only pulls about 1/2". Pull it, make sure you are truly pulling it out far enough.

Then, get on some wet grass and stomp on it while hanging your head out looking at the front wheel.

If it spins in the grass, you`re good to go.

Then use my how-to in my signature to convert your vacuum actuator to a locking cable pull.

I would never rely on that vacuum actuator. They are know for failure.

 

Well if he had it pulled all the way, and still didn't get power, that means the collar at the diff is the next most likely target. Do a search...I think there was a heavily referenced thread on diagnosing the parts once you eliminate the vacuum supply/actuator.

 

I just wanted to make sure he was giving it an accurate testing. And spinning it in the grass is funner than putting it up on jack stands. lol weeeeeeeee