I've had my 97 blazer for a year now and bought it from a backyard mechanic. I'm having trouble with the 4wd. Upon changing the radiator, i noticed a pair of vice grips under the battery tray,yes they came with the truck! Found out that the vacuum ball for the front diff was broken, so he vice gripped the cable to lock the diff. Ive been driving it that way for almost a year. The problem seems to be in the transfer case. When i lock it into 4wd,the front end binds and growls, especially when turning.It almost feels like the brakes are hanging.Also, when going back to 2wd, it doesn't seem to unlock right away. Is the problem in the vacuum, or is it the transfer case shift motor? I checked the vacuum lines and the wiring on the case, all looks ok. Also checked the cv joints and they are fine. My 93 jumped a little in 4wd when turning tight, but nothing like this. Any help is much appreciated

 

The vacuum ball is the reservoir for the HVAC and 4WD and needs to be repaired/replaced for both system to operate properly. When the engine is running, select 2WD at the dash switch, the vacuum line at the actuator under the battery should not have vacuum. When you select 4WD (hi or lo) the actuator should have manifold vacuum. As for the crow hopping, make sure the front differential fluid level is correct. Post your results.

 

Thanks for the info,just checked the transfer case with the front end disengaged, seems fine. goin to get an actuator and will check the front diff fluid. I'll let u know what i find, and i appreciate the help. This is the forth blazer/jimmy I've owned and all I've driven for the last 18 years!

 

Did you check for proper vacuum switching at the actuator? If it doesn't switch immediately when you push the button on the dash, it could very well be a faulty vacuum switch on the transfer case. The switch, (under $20) is far less expensive than the actuator, ($50) and much easier to replace.