1984 k5 blazer. 4 wheel drive will engage but hubs will not lock

Hey Gilbert ,it should be easy sitting in drivers seat all the way forward is 2wd down one is 4wd high next one down is netural and last one down is 4wd low on older cars you may have to roll a little forward and roll a little in reverse to get it to in gauge , the sane when taking it out of 4wd
hope this helped you , good luck
Woody

the front drive shaft when locked in 4 WD does drive the front diff
that inn turn drives the both front wheels if both have the same amount of traction
if one wheel is off the ground then the other will spin at twice the speed as that is what a differential is designed to do
now if you have a problem diff center ( broken teeth etc ) the there will be awful noises, clunks and bangs as the teeth from the pinion and crown wheel mismatch and hit on each other
no noises when in 4WD indicates a good diff center
the next problem will be a broken axle at the splines into the diff center spider gears ( same as one wheel off the ground or in a bog) the only wheels doing the driving are the rear wheels
next are the "u" joints or cv joints but again there will be lots of noises involved
lastly and the most frequent is the drives at the hubs
depending on the hub locks you have it will not n be locking in one or both wheels due to faulty actuator , dry damaged locking mechanism, stripped splines or not manually engaged
understand this --unless you have limited slip differentials or diff lockers on the vehicle any 2 opposing wheels or any wheels on the same side that have lost traction and regardless of being in 4WD or not you will not be going anywhere
so to fix --start at the drive hubs both sides to check actuation , engagement , then work back into the diff

does your four wheel light come on if not bad accuator

full size blazer? if so do you know if you have auto locking hubs on front or manual? the manual will have a dial to turn to lock or free. to shift into 4 high this can be done by just moving the shifter into 4hi at slow speeds. to shift into 4lo need to be in nuetral with vehicle stopped or rolling just a little bit like 1-2mph shift into 4 lo and shift back into drive same when shifting back into 2hi from low range.

manual or auto hubs?how do u now it is not engaging?.u can lift the front end up in 4 wheel make sure hubs r engaged .rotate the tire by hand ,and check to see if the drive shaft is turning [from the wheel to the front diff] u most likely have a bad locking hub.if it is not turning ur front tire is not locked up

Hi,
Do you have auto locking hubs on the front wheels, or manual locking hubs?
If you have auto locking hubs chances are they are not engaging properly and will need to be removed and spline sets checked for broken teeth on locking hub and locking shaft.
If you have manual locking hubs then check that they are firm when turning to engage them in the lock position.If they are light when engaging them to the lock position then they my have broken/worn out the locking hub and spline. Also check that the engaging spring inside the hub has enough tension to engage the hubs they may be broken. If the hub are all ok then you have a problem in the transfer box, where the 4WD lever is not meshing the transfer box properly. Hope this helps, let me know how you get on.

Jason

It's most likely the "four wheel drive actuator" This is located on the front differential housing. It's cylindrical shaped and has a large hex (about
1-1/4") and two wires coming out of it. Usually they short out and blow the fuse but, I've also seen where they just quit working and sometimes they just get slow to work. The "actuator" has a heating element in it and it warms up, some sort gas, causing it to expand thus engaging the front wheels. In cold weather it may take a minute or so for it to engage, so put in four wheel drive and wait for a bit and see what happens.

The light comes on indicating that the transfer case is engaged in 4wd, but that doesn't mean the hubs are locked. If you have automatic locking hubs, you should check to make sure they are working correctly. This GM vehicle may be equipped with vacuum locking hubs... meaning there is a vacuum line running from the transfer case selector to the hubs on each side. The vacuum makes the hubs lock into place. If those vacuum lines are damaged or missing, they wont lock. If you have electronic locking hubs, they may need to be replaced. Good luck.

There is a vacuum actuator mounted on the front differential that locks the shafts to engage four wheel drive.

if it is a full size k5 there is a snap ring around the inner housing to hold in the hub assembly remove it