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4x4 Wont Work 99 Sonoma ZR2


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tbach12
Novice

Sep 11, 2013, 10:02 AM

Post #1 of 10 (2125 views)
  post locked   4x4 Wont Work 99 Sonoma ZR2  

99 GMC Sonoma ZR2. 170000 miles 4.3 V6 Vortec

I bought this truck knowing that the 4x4 didnt work. I checked out the vaccuum system and everything seems to be running smoothly there. I took the transfer case off and sure enough, it was broken. I replaced the transfer case and now the vacuum system and the transfer case seem to have a smooth transition. Now when I put the truck into 4x4 (HI), there is a heavy thud and the truck will not move unless I give it gas. When i do give it gas, there is a loud repeating thud coming from the front of the truck. It is so bad as to disrupt the movement of the truck. The trans seems to shift beautifully while in two wheel drive, so unless there is a component in the trans that also switches when the truck is engaged into 4 wheel drive, I do not believe it is the transmission. I was thinking that it had to be somthing in the front end?


The transfer case is not brand new, I bought it used. So i could have gotten a faulty transfer case but I do not believe that is my problem, but I am not an expert.


Discretesignals
Ultimate Carjunky / Moderator
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Sep 11, 2013, 5:44 PM

Post #2 of 10 (2088 views)
  post locked   Re: 4x4 Wont Work 99 Sonoma ZR2  

What was broken on the old transfer case?





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tbach12
Novice

Sep 12, 2013, 6:06 AM

Post #3 of 10 (2074 views)
  post locked   Re: 4x4 Wont Work 99 Sonoma ZR2  

The gears/chain on the inside. When I spun the shaft with my hand, you could hear everything grinding around. And the vacuum valve (the little valve on the top of the transfercase with a slider on the inside, it has three hoses attached to it, was also jammed). I had heard that if that valve jams, it can cause your 4x4 to break if you try to run it.


Discretesignals
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Sep 12, 2013, 3:17 PM

Post #4 of 10 (2059 views)
  post locked   Re: 4x4 Wont Work 99 Sonoma ZR2  

All four wheels the same diameter? How about the front and rear axle gear ratios?





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tbach12
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Sep 13, 2013, 7:05 AM

Post #5 of 10 (2049 views)
  post locked   Re: 4x4 Wont Work 99 Sonoma ZR2  

The gear ratio is stock, so it should be the same I would think. The wheels/tires are indeed the same.


When I put it in 4x4, the truck will not even move unless I give it some heavy gas. Is it possible for the Gears to be broken in the front end? Are their gears in the front end?


(This post was edited by tbach12 on Sep 13, 2013, 7:08 AM)


Discretesignals
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Sep 13, 2013, 8:52 AM

Post #6 of 10 (2044 views)
  post locked   Re: 4x4 Wont Work 99 Sonoma ZR2  

There are gears in the front axle just as there are in the rear axle. The gear ratios have to be fairly close or else you'll end up with binding and broken stuff. It is possible someone could have changed the rear end or the gear ratio in the rear end, so it is important to confirm that.

With the transfer case in 2 HI can you spin the front drive shaft by hand? If you can, jack up the front of the vehicle, then apply vacuum to the front actuator. Next, turn the front shaft and make sure the front tire(s) spin without binding.





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(This post was edited by Discretesignals on Sep 13, 2013, 8:53 AM)


tbach12
Novice

Sep 20, 2013, 5:23 AM

Post #7 of 10 (2019 views)
  post locked   Re: 4x4 Wont Work 99 Sonoma ZR2  

Update: I can spin the front drive shaft by hand when 2HI is engaged. I applied vacuum and the wheels would no spin. They lock up.

New symptom, When driving down the road, there is grinding going on in the front while truck is in 2HI


Discretesignals
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Sep 20, 2013, 4:50 PM

Post #8 of 10 (2013 views)
  post locked   Re: 4x4 Wont Work 99 Sonoma ZR2  

Your probably going to have to pinpoint where that grinding noise is coming from.





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tbach12
Novice

Oct 14, 2013, 10:06 AM

Post #9 of 10 (1980 views)
  post locked   Re: 4x4 Wont Work 99 Sonoma ZR2  

I figured it out. The guy that owned the car before me had let the front differential go dry. It was starting to cease up and that is where the grinding came from. I replaced the front differential and now everything seams to be in working order. Thanks for all the help!


Discretesignals
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Oct 14, 2013, 1:14 PM

Post #10 of 10 (1977 views)
  post locked   Re: 4x4 Wont Work 99 Sonoma ZR2  

No fluid in the front end would definitely cause an issue. Glad to read that you got it solved. Thanks for the follow up.Smile

Closed as resolved to prevent spamming and hijacking.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.






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