HELP! Bad transfer case???

Hi guys, I've got a '93 Silverado 1500 Ext. cab. 4x4 350 auto ( 200,100 miles ). Occasionally, at times while accelerating there will be a grinding noise ( I would compare it to grinding the gears in a manual tranny when not clutching ) coming from the transfer case only for a split second. If you let off the gas and ease back into it the noise goes away. It doesn't seem that anything is slipping and it still goes into 4x4 but obviously something is wearing out somewhere. I'm 99% sure it is coming from the transfer case. I usually do most of my own repair work when I can, however, I've never had to tackle a transfer case before. So, my questions are: 1. What could be causing the noise in the transfer case when the truck is in 2-HI?
2. If it needs to be rebuilt, is it pretty self explanitary that I could do it myself.

Money is tight right now and if it is a simple task I'd rather not take it into a shop. I'm just looking for some opinions from some of you who have had experience working on these transfer cases.
Thanks in advance for any help....

Hi guys, I've got a '93 Silverado 1500 Ext. cab. 4x4 350 auto ( 200,100 miles ). Occasionally, at times while accelerating there will be a grinding noise ( I would compare it to grinding the gears in a manual tranny when not clutching ) coming from the transfer case only for a split second. If you let off the gas and ease back into it the noise goes away. It doesn't seem that anything is slipping and it still goes into 4x4 but obviously something is wearing out somewhere. I'm 99% sure it is coming from the transfer case. I usually do most of my own repair work when I can, however, I've never had to tackle a transfer case before. So, my questions are: 1. What could be causing the noise in the transfer case when the truck is in 2-HI?
2. If it needs to be rebuilt, is it pretty self explanitary that I could do it myself.

Money is tight right now and if it is a simple task I'd rather not take it into a shop. I'm just looking for some opinions from some of you who have had experience working on these transfer cases.
Thanks in advance for any help....

sounds like bearings to me...

the transfer case still spins even when in 2WH it just doesn't engauge the front axle.

essentially being in neutral.

You may have a problem with the 2wd / 4wd selector lever on the transfer case. It may be loose, worn etc and allowing the case to temporarily pop out of 2wd.

I had the same problem with my Cherokee. The lever was vacuum-operated and would pop out when accelerating. Stepping on the gas reduced the manifold vacuum, allowing the lever to move. When I fixed a vacuum leak, I had no more trouble.

I do not know if your linkage is vacuum, electric or mechanical. But take a look at it and make sure it operates properly.

I know that the actual engagement of the case is electronically controlled. When you shift the lever by hand that activates an electronic switch/solenoid that actually shifts the transfer case. I know that my solenoid has been getting bad for a few years because when you shift to 4 HI it takes a while for the 4x4 light to come on and actually engage the front shaft. Could a faulty solenoid be causing the problem? Has anyone ever had a bad solenoid cause this on one of these trucks? I'll probably start by replacing the solenoid since I know it is getting bad. If that doesn't do it I suppose I'll have to pull the case and inspect it internally. Does anybody know what these solenoid switches cost? I've heard in the past they are pretty spendy...

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

Does the noise happen when you select 4HI or even when driving in 2HI? If only 4HI, you have a vacuum leak at the actuator line or diaphragm.

While you're under there, check your vacuum lines running from the transmission for transmission fluid. There is a 4wd vacuum switch with three tubes running to it screwed into the left side of the tranny with the tubes going up and over the tranny. Sometimes it will fail and cause transmission fluid to get sucked into all the actuator lines, diaphragm, vacuum bulb, etc., wreaking havoc with 4wd operation. You'll have to blow out all the lines, drain the actuator (don't use compressed air here!) and the plastic vacuum bulb, and replace the switch...not an expensive fix but plenty of work to clean it all out.

It happens when in 2HI. It's not muddy enough around here right now to drive around in 4Hi too much but I would assume it would do it in 4Hi also.

It does not happen too often but I'd like to take care of it before winter sets in and I wreck it any further. I'm assuming that whatever connects between the tranny and transfer case internally is wearing out or already broken since it only happens while on the gas = more torque applied seems to make noise happen more often. If you're real easy on the pedal it usually will not happen. Like I said before, I'm not familiar at all with transfer cases but I'll probably pull it and educate myself a bit. If I pull it out and am able to fix it what do I need to put it back together? Is there a seal kit or gasket set to buy? Also, I'm assuming these older ones take ATF, not the green crap that my '02 has in it.:)

I recommend you check the snap ring before dropping the tcase itself. It can be checked by dropping the drive shaft are removing the tail shaft housing.

//2000CAYukon

I'll check that first. Hopefully I can make time to get to it this weekend. I'll post back in a few days with my findings....Thanks.

I know that the actual engagement of the case is electronically controlled.


No its not the lever is mechanically connected to the T-case, the light is for the front axle.

You ether have a bad range fork in the T-case or the snap ring is busted.

If there's tranny fluid in the actuator system, it can prevent full disengagement of the front diff as well that causes the gear-grinding sound. The transfer case switch is a cheap fix and common problem...that's why I suggested it. Check it before wrestling with the TC.

Finally got a chance to tear into it. It was the snap ring, broke in three pieces. Easy fix, all is well, thanks a bunch guys....