4x4 will not engage on my 1994 Z-71..help??

fourwheelhorsem · 07-23-2008, 02:42 PM

HI all.. I'm new to this forum.. but already, as I read some of the previous threads, I can see it's value. OKAY.. I recently purchased a very nice looking and running GMC truck. I tried the 4x4 out before I purchased it..it was on the road, and dark, but I did hear the actuator work, so I assumed when the light for 4x4 came on, that it was engaged. I was wrong, and later when the truck was mine, I and i decided to do a bit of off- roading, I noticed my front tires were not spinning, nor pulling and nearly got stuck. I took it home and spun a little in my driveway when the 4x4 was engaged, only to see that my rear tires were the only ones making marks in my driveway nearly. So.. after doing a little bit of investigating ( on my own) I jacked the truck up, removed the actuator, and engaged the 4x4, it seems to come out far enough. So.. the actuator works( or at least I think it's pushing out far enough). I jacked the front tires off the ground and turned the front drive shaft.. it spins when the 4x4 is not engaged. When the 4x4 is engaged the front drive shaft will not spin. Sooooo I think the transfer case is working. also when the front tires are off the ground and the 4x4 is engaged I turned the front tires to see if the front drive shaft would spin... it didn't. I am kinda lost with this ...I do know that the 4x4 has not been used alot and it seems to make no weird, unusual noises. The 4h and 4lo seems to work well.. just without the front tires doing thier job.
thanks in advance for any help!!

stumpuller454 · 07-23-2008, 03:05 PM

well sounds like you need to jack the front wheels free and with your actuator removed (in 2wd) use the end of a small hammer (or something) and see if you can engage the front differential, when it works you should be able to "drive the drivers side wheel by turning the passenger side" (normaly in 2wd operation turning one wheel doesn`t turn the other) SOUNDS like either the actuator is "week" or the collar in which it engages the differential is pooched. the actuators are a common prob...

fourwheelhorsem · 07-23-2008, 05:40 PM

just out of curiousity IF the collar is junk... is it a big deal to replace it? I probably will not be the one to do the job...too much overtime right now... and to be 100% honest, I may get in a bit over my head on that one. THANKS for your quick reply!

Dark C · 07-25-2008, 02:52 AM

Try backing up to lock the transfer case.

leolkfrm · 07-25-2008, 06:20 AM

sometime when an actuator works it comes out but not strong enough to stay out. Follow stumpuller's directions to determine where the problem is then its easier to give suggestions what to do next to solve your problems.

fourwheelhorsem · 07-25-2008, 01:46 PM

I will follow stumppullers directions. I did put the truck in reverse to engage the 4x4 ..nothing. I removed the actuator to see how far it came out.. it seemed to come out all the way..I will use a small hammer, piece of wood ect. to try and manually engage it.. then spin the front tires and see what happens. IF it engages.. I know it's the actuator.
anyhow.. I'll work on it sunday or monday... weekends a re fairly busy for me.
thanks guys.. I'll reply with a post when I know somthing.

fourwheelhorsem · 08-11-2008, 07:37 PM

okay... I tore the half shaft outa the truck..I also got the axle housing out along with the drive axle. I found that the thrust plate that the gear rides up against was bent, all that is is a kinda thick washer that has two tabs on it, both tabs are in place, but one of the tabs was bent in a downward position.. and the clip that holds the gear in place is possibly weak.. or broken? How far around the inside of the gear is the snap clip supposed to go? I know when I took the half shaft out, I could ALMOST, but not quite, slide the drive axle out of the housing and pig without taking the flange bolts out. Indicating that the snap ring was weak or bent..?Is there anywhere else I can get a better diagram on the web? The new chiltons manual is kinda anemic and shows kinda bad pics.. but still MUCH better than the Haynes I was gonna get. any thoughts on this?
thanks

stumpuller454 · 08-11-2008, 09:41 PM

the drivers side axle can be removed from the housing without anything else done, it is designed to be servicable in-vehicle, the passenger side is some more work...i have a pic here from the GM manual but i bet you it is useless, no chart for part descriptiona and its freakin small

stumpuller454 · 08-11-2008, 09:41 PM

sorry that IS totally useless...

fourwheelhorsem · 08-12-2008, 02:27 PM

hmmm.. I have that same diagram in my chiltons. I just purchased a new snap ring and thrust washer..total of 14.00$ BUT, the snap ring doesn't seem to hold the gear any better than the original.. wonder if the ring is actually supposed to hold really tight... or is it functioning correctly? No one at the dealership ( where I had to get the thrust washer and snap ring) really knew.

07-23-2008, 02:42 PM	#1
fourwheelhorsem Junior Member Join Date: Jul 2008 Posts: 7	4x4 will not engage on my 1994 Z-71..help?? HI all.. I'm new to this forum.. but already, as I read some of the previous threads, I can see it's value. OKAY.. I recently purchased a very nice looking and running GMC truck. I tried the 4x4 out before I purchased it..it was on the road, and dark, but I did hear the actuator work, so I assumed when the light for 4x4 came on, that it was engaged. I was wrong, and later when the truck was mine, I and i decided to do a bit of off- roading, I noticed my front tires were not spinning, nor pulling and nearly got stuck. I took it home and spun a little in my driveway when the 4x4 was engaged, only to see that my rear tires were the only ones making marks in my driveway nearly. So.. after doing a little bit of investigating ( on my own) I jacked the truck up, removed the actuator, and engaged the 4x4, it seems to come out far enough. So.. the actuator works( or at least I think it's pushing out far enough). I jacked the front tires off the ground and turned the front drive shaft.. it spins when the 4x4 is not engaged. When the 4x4 is engaged the front drive shaft will not spin. Sooooo I think the transfer case is working. also when the front tires are off the ground and the 4x4 is engaged I turned the front tires to see if the front drive shaft would spin... it didn't. I am kinda lost with this ...I do know that the 4x4 has not been used alot and it seems to make no weird, unusual noises. The 4h and 4lo seems to work well.. just without the front tires doing thier job. thanks in advance for any help!!

07-23-2008, 03:05 PM	#2
stumpuller454 Senior Member Join Date: Dec 2007 Location: Alberta Posts: 786	well sounds like you need to jack the front wheels free and with your actuator removed (in 2wd) use the end of a small hammer (or something) and see if you can engage the front differential, when it works you should be able to "drive the drivers side wheel by turning the passenger side" (normaly in 2wd operation turning one wheel doesn`t turn the other) SOUNDS like either the actuator is "week" or the collar in which it engages the differential is pooched. the actuators are a common prob... __________________ 1998 GMC K2500 Ext.cab short box 454ci *1951 Chevrolet 1420 pickup like new!* Red seal certified Journeyman Automotive Mechanic

08-11-2008, 09:41 PM	#8
stumpuller454 Senior Member Join Date: Dec 2007 Location: Alberta Posts: 786	the drivers side axle can be removed from the housing without anything else done, it is designed to be servicable in-vehicle, the passenger side is some more work...i have a pic here from the GM manual but i bet you it is useless, no chart for part descriptiona and its freakin small Attached Thumbnails __________________ 1998 GMC K2500 Ext.cab short box 454ci *1951 Chevrolet 1420 pickup like new!* Red seal certified Journeyman Automotive Mechanic

08-11-2008, 09:41 PM	#9
stumpuller454 Senior Member Join Date: Dec 2007 Location: Alberta Posts: 786	sorry that IS totally useless... __________________ 1998 GMC K2500 Ext.cab short box 454ci *1951 Chevrolet 1420 pickup like new!* Red seal certified Journeyman Automotive Mechanic

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07-23-2008, 05:40 PM	#3
fourwheelhorsem Junior Member Join Date: Jul 2008 Posts: 7	just out of curiousity IF the collar is junk... is it a big deal to replace it? I probably will not be the one to do the job...too much overtime right now... and to be 100% honest, I may get in a bit over my head on that one. THANKS for your quick reply!

07-25-2008, 02:52 AM	#4
Dark C Junior Member Join Date: Jul 2008 Posts: 1	Try backing up to lock the transfer case.

07-25-2008, 06:20 AM	#5
leolkfrm Senior Member Join Date: Mar 2008 Location: N.Y. Posts: 953	sometime when an actuator works it comes out but not strong enough to stay out. Follow stumpuller's directions to determine where the problem is then its easier to give suggestions what to do next to solve your problems.

07-25-2008, 01:46 PM	#6
fourwheelhorsem Junior Member Join Date: Jul 2008 Posts: 7	I will follow stumppullers directions. I did put the truck in reverse to engage the 4x4 ..nothing. I removed the actuator to see how far it came out.. it seemed to come out all the way..I will use a small hammer, piece of wood ect. to try and manually engage it.. then spin the front tires and see what happens. IF it engages.. I know it's the actuator. anyhow.. I'll work on it sunday or monday... weekends a re fairly busy for me. thanks guys.. I'll reply with a post when I know somthing.

08-11-2008, 07:37 PM	#7
fourwheelhorsem Junior Member Join Date: Jul 2008 Posts: 7	okay... I tore the half shaft outa the truck..I also got the axle housing out along with the drive axle. I found that the thrust plate that the gear rides up against was bent, all that is is a kinda thick washer that has two tabs on it, both tabs are in place, but one of the tabs was bent in a downward position.. and the clip that holds the gear in place is possibly weak.. or broken? How far around the inside of the gear is the snap clip supposed to go? I know when I took the half shaft out, I could ALMOST, but not quite, slide the drive axle out of the housing and pig without taking the flange bolts out. Indicating that the snap ring was weak or bent..?Is there anywhere else I can get a better diagram on the web? The new chiltons manual is kinda anemic and shows kinda bad pics.. but still MUCH better than the Haynes I was gonna get. any thoughts on this? thanks

08-12-2008, 02:27 PM	#10
fourwheelhorsem Junior Member Join Date: Jul 2008 Posts: 7	hmmm.. I have that same diagram in my chiltons. I just purchased a new snap ring and thrust washer..total of 14.00$ BUT, the snap ring doesn't seem to hold the gear any better than the original.. wonder if the ring is actually supposed to hold really tight... or is it functioning correctly? No one at the dealership ( where I had to get the thrust washer and snap ring) really knew.

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