Clunking and stuck in four wheel drive

1999 CHEVROLET BLAZER
180,000 MILES • 4.3L • 4WD • AUTOMATIC
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CHRIS FISCHER
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A loud clunking started a couple weeks ago, so we put it in shop. when it got real loud personal shop we noticed it is stuck in four wheel high, replaced actuator, cable, vacuum lines and checked electronic solenoid. We took out four wheel drive driveshaft and drove and no noise is present. When it is is in, a real loud clunking louder when cornering is unbearable. And yes, we replace the whole fry end, ball joints, CV joints, tie rods, Idler arm. Any suggestion? I need help bad and is only transportation!
Jan 25, 2017 at 2:07 PM
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CHRIS FISCHER
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Forgot to mention, we have checked the bearings, and universals in both drive shafts.
Jan 25, 2017 at 3:25 PM
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HMAC300
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was it full of fluid or did you not check? do what is in picture and get back to us. although, it may be and sounds like it is an internal problem.
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Jan 25, 2017 at 3:39 PM
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CHRIS FISCHER
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Yes, fluid level good and no burnt smells, however there is a small leak, looks like oil, coming from the front "pumpkin".
Jan 25, 2017 at 6:18 PM
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CHRIS FISCHER
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Can I take four wheel drive shaft out and drive truck that way or will it cause more damage?
Jan 25, 2017 at 6:27 PM
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STEVE W.
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No problem pulling the front shaft. The only thing I can think of that would be clunking in the front would be if maybe a couple teeth were damaged on the ring or pinion. Or you have a bad inner joint on one of the front axles. If one was pulled out just enough for the bearing to come off and it went back it it would make a lot of noise.
Jan 25, 2017 at 9:01 PM
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STEVE W.
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Here is a video with some 4X4 noises, is this what you hear?

https://www.youtube.com/watch?v=xtoL4FjerlM
Jan 25, 2017 at 9:07 PM
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CHRIS FISCHER
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Yes, that is the clunking. when we take front drive shaft out it still makes the noise, but not that loud. Driving last night with out front drive shaft, we made a couple sharp turns back and forth and heard a pop, then around went away. Still have yet to hear it! I am afraid to put front shaft back in and make the sound return!
Jan 26, 2017 at 4:57 AM
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CHRIS FISCHER
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I have four t-cases from other parts blazers. Question, can I replace my four button auto four wheel Dr with a third button four wheel drive that does not have auto. do I change the TCCM and/or cables/connectors? do I have to reprogram the brains together, etc? One of the extra t-cases my have the auto four wheel, but I do not know which one, how can I cross reference these to find the auto t-case out of the other t-cases? Thanks to all who have responded! Hope to return the favor to someone else in need. By the way: the Blazers were scraped, only kept parts, so I do not have the VIN number's.
Jan 26, 2017 at 6:07 AM
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HMAC300
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go by the ID tag at back of case. it should be same number either a NV233-236 etc. otherwise you will have problems. See picture.
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Jan 26, 2017 at 7:00 AM
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STEVE W.
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Have never looked at swapping the Auto T-case. I think you would need to swap a lot of parts. The T-case, TCCM, wiring harness, switch are all different. Then there are the extra speed sensors and a different ABS system. The BCM is different as well as different ECM programming for the auto controls.

The auto box will be a NV 236.
Jan 26, 2017 at 10:07 AM