Transfer Case Grinding Noise

stadt11 · May 23, 2010

My transfer case has started making a horrible grinding noise. First I thought it was coming from the driveshaft or the front/rear diff, but wasn't sure. I put the truck on jack stands and put the truck into gear and determined it was definitely the transfer case.

In the first video, you can really hear it start as soon as I put it in gear (@ 5sec), and then I rev up the engine and let off and can really hear it (@ 30sec) - this is how it sounds running down the highway about 50-60mph. I put it into 4WD (@ 1min) just to verify it's not just doing it in 2WD and it's doing it in 4WD as well. Later in the vid I switch it to Auto4WD (about 1:45) and it's doing it there too.

Another angle, I could also feel it by touching the case (@ 25sec) that it was indeed from the transfer case so my ears were not deceiving me.

I checked the fluid level it and it is just below the fill hole, so the noise is not from lack of fluid. What could it possibly be, loose chain, or...?

I have a service appt tomorrow morning to have it checked over, but didn't know if anyone would have a better idea what the problem is inside that I can tell the service technician so they aren't spending all day hunting for the answer.

jocko50 · June 8, 2010

Thanks for the info.

That must be it but is that all you think that might need replacing(clip) or will there be visual confirmation that a bearing or pump needs to be replaced?(i know its hard to say with out seeing it). So this clip is out of place and is casuing the pump to be out of positon?And this is causeing the noise? Or is to late and now the bearing is gone too? Thank you.

stadt11 · June 8, 2010

Sounds like you have a clip problem JJ, here's some info:

Current TSB for this can be found at this link ... http://ww2.justanswer.com/uploads/Bluegori...r_case_hole.pdf

Found a post on another site saying the "hole is 1/2 way up the backside of the case right above the tailshaft".

original clip

broken clip

redesigned clip

More Info:

Why does this happen? Basically the magnesium alloy is too soft when heated - http://www.sonnax.com/tech-articles/TASC-TIP-11-07.pdf

Found that Sonnax has designed a new Pump Plate - http://www.sonnax.com/announcements/100246-02K.pdf

gmtech4 · June 7, 2010

yes oh lust worm lol

stadt11 · May 27, 2010

Fixed! She runs smooooth!

What happened:

Rear bearing came apart, chewed up the pump, the reluctor wheel rubbed on the speed sensor, and rear bushing was worn. Completely overhauled T-case with parts listed below and she's good as new.

Here's everything they replaced:

Pump Assembly

T-Case Housing

Speed Sensor

Bearings

Wheel

Pump Clip (thanks to Draenor for sending that to me, I called my service tech to see if they'd replace the clip with the new P/N and he said he did - they keep that part # handy, they said they're seeing a lot of "pin-hole" problems lately because of that clip)

Good thing for GM's Powertrain Warranty!

jro909 · June 7, 2010

these t cases are very easy and a good driveline guy can have it out and apart in no time (which has nothing to do with what you'll pay) and they will see something,dont worry,do you know jro?

Thinking of me are you?

jocko50 · June 8, 2010

Hello everyone !

What a useful thread !!!!!

Here's my scenario.......

My transfer case is leaking pretty bad and took a look and thought my case was cracked.

I then noticed a couple of pin holes on the case.

There is a humming noise comming from somewhere as well and pretty sure it the transfer case.

Is this common for this transfer case? Would i have to rebuild as well? or is it cheaper to buy used again?

Thanks again. 99 silverado-5.3L 4x4

gmtech4 · May 23, 2010

these t cases are very easy and a good driveline guy can have it out and apart in no time (which has nothing to do with what you'll pay) and they will see something,dont worry,do you know jro?

mhorgan · June 8, 2010

I think Ive got mine figured out. After tearing apart my rear brakes, I finally found the noise in the rear diff. The noise would go away when the truck was on the lift and then come back when you put a load on it, but it resonates through that big hollow aluminum driveshaft and makes you think its coming from everywhere! Sounds like I have a pinion bearing or side bearings that are spun, so Im looking for a salvage rear end to throw in the old work truck. Anybody got an extra?

mhorgan · June 7, 2010

My truck is making a similar noise, but when I put it on the jackstands I couldnt hear it. It only does it when its on the road and Im giving it gas, but its that same noise so Im thinking its the rear output bearing or the chain hitiing the case. It sounds the way something scrubbing inside a brake drum would. I bought this truck at 165k and its at 193 now, and Ive never changed the t case fluid so Im going to check my fluid level before I panic.