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1990 blazer 4x4 not engageing

T

taurussho24v

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Full size 350 auto broke u joint on drivers side . Before it was replaced my father plowed with it in 4x4 he said it made noise but plowed. the axel and stub shaft then needed to be replaced also. The shaft from the transfer case to front axle spins in 4x4 under power. but the front wheels do not. Pulled front diff cover all looks ok ring pinion spiders. it has the automatic hubs. Also shaft to axel from transfer case will not spin in 4x4 but will spin in 4x2 with me trying to manipulate from under truck. Any help would be appreciated I'm getting snowed in truck only has 64k. It has the lever of the floor to engage 4x4. Had truck since new the 4x4 light hasn't worked since 94

Does it have the actuator I keep reading about?

Install manual hubs or am I missing something
 
Last edited:
I think you are going to need to rewrite something.
You said the front shaft spins in 4X4, then says it doesn't.
Automatic hubs are always suspect.
 
Edited

I fixed my mistake under power stuck in the driveway in 4x4 the shaft from the transfer case to front diff spins but front tires do not spin. Under the truck up in the air when I have the truck in 4x4 I cannot spin the shaft manualy when I place it in 2wd I can spin it manualy and I added a question if it has the 4x4 actuator that chevy seems to be known for going bad if it dose have it where is it's location.
 
Sounds to me like the hubs are not locking...your getting power to the front diff and axles in 4WD,but the hubs aren't locking and driving the tires...automatic hubs suck,manual ones are more reliable,but I've had my share of those failing to lock in at the worst possible times also..

I dont know if you have an actuator on a 90 model truck,far as I know solid axle trucks never had that setup,only the "new" style ones with the CV style front axles...
 
taurussho24v said:
I fixed my mistake under power stuck in the driveway in 4x4 the shaft from the transfer case to front diff spins but front tires do not spin. Under the truck up in the air when I have the truck in 4x4 I cannot spin the shaft manualy when I place it in 2wd I can spin it manualy and I added a question if it has the 4x4 actuator that chevy seems to be known for going bad if it dose have it where is it's location.
Click to expand...

The thermal actuator that goes bad is on newer IFS trucks. If you're talking about a solid-axle Chevy, then you don't have one.

If the driveshaft spins but the wheels don't, then the hubs aren't locking. The automatic hubs are well-known for failing, so yes, manual hubs are a good idea.

-- A
 
OK, now it makes sense.
You will not have both automatic hubs and an actuator.
Its either/or. Not sure when they switched from the hubs to the actuator, but 90 sounds close. Look for a wiring connection on the front axle assembly, passenger side, a short distance from the diff.

If its there, there is an actuator that goes bad. Its a sealed cylinder with a low boiling point fluid and an electric heater.
When you shift to 4wd, the heater boils the fluid, and the pressure pushes a piston out and engages the front axle.
When the front axle engages, it hits a switch that turns on the light.

The actuator is fairly cheap, I think, and easy to change. I think the newer ones last longer.
But,Warn makes or made a mechanical replacement. If you install one of those, you have a knob on the dash that engages the axle manually.
 
Ok i put in manual hubs locked them got ten feet out of the garage felt like i was in 4wd was not got stuck. rear wheels spinning fronts not moving, shaft going to front diff spinning from transfer case the front u joints are not spinning while truck is stuck when i was driving into the garage they moved with wheel speed.

Only thing questionable about installing hubs was the snap ring does that go on the outer grove or the second grove in only grove i could get to was the outer. Im One armed at the moment.
 
looks like it's time to remove the front cover to see what is broken.
 
Pulled the cover before I put in the hubs in all the teeth looked good on ring pinion and spiders I was able to spin the shaft from the transfer case the gears went around all looked good fluid was nasty ( never changed before) but no metal flakes no teeth on the bottom as I expected I'm lost. Unless the pinion is cracked and kinda just feels ok??? I'm usually never this lost but it's freezing in ny right now so working on stuff sux. Every once in awhile it makes a grinding noise from the front but pops was beating on it trying to get it unstuck? Could the transfer case not be giving enough power? To spin the front axle?
 
when you put it in 4 wheel, does the front shaft turn while in gear and brakes applied. Have you placed it on jack stands to see if every thing in moving in 4wheel. If you so did everything rotate. i think you said that the shafts in the housing were turning when you moved, if so then the front hubs should be engaged.
 
Shaft from transfer case does spin brakes applied and I haven't been able to get the whole thing In the air. Yes I saw the u joints moveing with wheel speed in garage no power to them tho.
 
Update

Update pops just said he hit a tree stump with the plow. Plows bent a little frames slightly tweaked so it hit hard but had 4x4 after the hit don't know if it's pertanent info or not. Maybe what Prompted the u joints to get loose.
 
Pull both axle shafts, bet one is broken in the Tube and being an open dif. all it does is spin the broken shaft inside the Tube.
 
Thank you never thought of that left side is brand new right side was the side I heard the noise. I'll let you know when I get it apart.
 
Jack the left front (all other tires on the ground, t-case in 2wd) up in the air and try spinning the tire with the hub unlocked and then locked. With the hub unlocked the tire should spin but the u-joint will not. The hubs locked will cause the u-joint to spin and the driveshaft (between axle and t-case). Then do the same to the right front.

If you have the hub locked and the u-joint spins but the driveshaft does not, you either have a broken axleshaft or something is broke inside the diff.
 
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