1997 suburban transfer case/differential problems

My 97 burb was running great, I seldom used the four wheel drive in it . I put it in four wheel high one day at work briefly, that night it started......
when I would take off from a stop at 5 or 10 mph it would grind and pop like it was trying to engage the front end.. at one point I waited for the sound and at that moment i pushed the 4 high button.. it engaged rather roughly but in 4 high the rest of the way home NO sound NO grind......
I have talked to several mechanics who all have theories, ranging from rear bearing clip, electronic acctuator motor, the switch that sends a signal to the acctuator?, transfer case rebuild, front end rebuild, suspicious fire, driving off a cliff, ? ? ?

The one thing I am pretty sure about is that the transmission is not the problem..95% sure anyway.....

the last time I drove it home in 4 high it spun out of gear backing in my driveway. I immediately put it in neutral, waited for the rpm's to slow and switched back to 2 wheel drive and backed it right in...

xfer case 243-c , electronic shift 3 position 2, 4h, 4L
168,000 mi. ,1/2 ton.....

My 97 burb was running great, I seldom used the four wheel drive in it . I put it in four wheel high one day at work briefly, that night it started......
when I would take off from a stop at 5 or 10 mph it would grind and pop like it was trying to engage the front end.. at one point I waited for the sound and at that moment i pushed the 4 high button.. it engaged rather roughly but in 4 high the rest of the way home NO sound NO grind......
I have talked to several mechanics who all have theories, ranging from rear bearing clip, electronic acctuator motor, the switch that sends a signal to the acctuator?, transfer case rebuild, front end rebuild, suspicious fire, driving off a cliff, ? ? ?

The one thing I am pretty sure about is that the transmission is not the problem..95% sure anyway.....

the last time I drove it home in 4 high it spun out of gear backing in my driveway. I immediately put it in neutral, waited for the rpm's to slow and switched back to 2 wheel drive and backed it right in...

xfer case 243-c , electronic shift 3 position 2, 4h, 4L
168,000 mi. ,1/2 ton.....


if the drive train is dropping out of 4WD,, it would indicate the transfercase has problems...have you checked the fluids in any of the componets,,,frt diF,transfercase,,tranmission for fluid condition...?


THIS IS ONLY A PART TIME 4wd SYSTEM...

Could be a broken snap ring in the transfer case. See http://www.drivetrain.com/parts_catalog/transfer_case_replacements_and_parts/transfer_case_saver.html

//2000CAYukon

I read a thread about the front diff accuator. This person said that you can remove the accuator by unthreading it. plug the hole and road test it, to see if that is the problem.... I tried it , no difference.... Does this narrow my search to the transfer case itself.????????By process of elimination, that is where I'm leaning....:uhoh::runaround::crying:

By the way I have changed all the oil, front diff, rear diff, and xferd case....the rear oil looked normal. the xfer case looked ok w/very few tiny mettalic flakes in it. the front diff oil looked very milky like varnish....

I have read several posts about broken rear snap rings...... that sounds possible, however none of the local parts stores know what that is, or have anyway of looking for it...Should I see the local dealer or is there a proper name that the parts guys would understand?? I would prefer oem parts over china stuff.

I read a thread about the front diff accuator. This person said that you can remove the accuator by unthreading it. plug the hole and road test it, to see if that is the problem.... I tried it , no difference.... Does this narrow my search to the transfer case itself.????????By process of elimination, that is where I'm leaning....:uhoh::runaround::crying:

By the way I have changed all the oil, front diff, rear diff, and xferd case....the rear oil looked normal. the xfer case looked ok w/very few tiny mettalic flakes in it. the front diff oil looked very milky like varnish....

I have read several posts about broken rear snap rings...... that sounds possible, however none of the local parts stores know what that is, or have anyway of looking for it...Should I see the local dealer or is there a proper name that the parts guys would understand?? I would prefer oem parts over china stuff.


if the front dif oil was milky water got into it ...this could be the vent hose fell off...

flakes in the transfercase oil is very bad....what color was the fluid blue or a gray color...if gray or black this is not good.

the front diff locking acutator motor does not engage 4WD only the transfercase encoder motor does this...


the front diff locking actuator locks the front axles together,,,now they rotate as one solid axle..

We tried 2 aftermarket encoder motors with no luck. Gave up and took to tranny shop. He puts a GM encoder unit on and it work fine. And over $700 bill. After the bill he says the aftermarket encoders are no good.