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  1. #1

    Default Transfer Case Noise [Expired Topic]

    My dad has a 94 K1500. He told me over the weekend that when in 2wd, it sounds like the front differential is trying to engage. If he puts it in 4wd everything works fine and quiet. I have not checked myself yet, but I thought I would throw it out here to you guys to see if someone else has had this problem and could tell me what to expect. Sorry it's so vague, I'll fill in more information after I look at it.


    99 K 1500 Suburban
    78 Silverado Big 10 w/factory 454
    00 S-10 Blazer
    1976 Trans Am
    1980 Honda CB900 Custom

  2. #2


    The front wheels are engaged with a thermal engagement system. (forgive, I can't think of the exact name) The way the device works is a small charge of gas sits inside a cyclinder, and in front of a heating element. when the gas is heated it builds pressure in the cylinder, and pushes a small plunger forward, and engages the clutch. It's possible that the plunger is failing to completely disengage. They don't usually fail like that. Usually they lose the gas charge, or the heating element dies, and fail to engage. If the front dif is only partially engaged, or nearly engaged it will sound like someone who's just learning to shift in a standard trans. Lots of hard gear grinding. As an easy test you can unscrew the thermal actuator about half way, and then try driving it around. Or you can take it out completely, as long as you have something to plug the hole with, like the temporary rubber freeze plugs. Otherwise you'll lose diff heavy gear oil.

    If you find that the actuator is faulty you'll have to replace it, and this may be a better alternative.

    I recently made a perm-lok (bottom of webpage) out of my old thermal actuator, metal tent spike, a large rubber eraser, and 3 set screws. If I ever find the time, I'll post a tutorial. Of course, if enough people ask about it, I may post it sooner....

    Hope this helps you.

  3. #3


    Yesterday, I talked to a local transmission shop and the owner told me that these things are prone to breaking a snap ring just in front of the rear drive shaft in the transfer case. He said I have to remove the drive shaft and then the output shaft housing and I should find the broken ring just inside. He gave me a new re-designed snap ring to replace the broken one with (GM part # 12470554). I pulled the rear driveshaft and output shaft housing and there was the broken snap ring. I installed the new one, reassembled and everything works perfect, no more grinding. In all, it took about 45 minutes.

  4. #4



  5. #5
    Master Mechanic Dr_Zero's Avatar
    Join Date
    Mar 2006
    Sunny Florida


    I wish I had seen this a few weelks back when I had my u joints changes I would have had this changed just to be safe.

    I found also a transfercase saver kit has anyone tried this it looks pretty cool!
    My trucks!

    1996 GMC Suburban SLT
    1997 GMC Yukon SLT

  6. #6


    HELP! I was just driving my 96 Sub and it started making this strange noise when I pulled away from the stoplight. Sounded to me like it was either a bad/dry bearing or maybe a chain slipping in the transfer case. It wasn't so much a grinding noise, but more like the rattling sound of a dry bearing at high speed if that makes sense. Sounded pretty nasty. Truck shifted fine, just made that funky noise intermittently. And sounded a lot like it was coming from the xfer case or thre tranny. It was in 2WD. Is this a symptom of the aforementioned snap ring breaking?

    Want to get this one sorted out, but I know nothing about transfer cases.


  7. #7


    That sounds like what my dad's was doing, mostly happened when starting from a stop. Have you tried to put it in 4hi to see if it quiets down? If it does, I would think it is the snap ring. It is a pretty easy and cheap fix if you have some basic tools and know how.

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