Need Help - '03 Silverado

jth7186 · May 29, 2003

Alright, a while back I mentioned an odd noise I kept hearing from my truck at around 38-46 mph in overdrive at approximately 1200 rpms. It happens when the truck is coming back under power to hold speed, like when you come off the bottom of a hill and start up another while trying to hold your speed at 45 mph. The noise sounds like a heavy rattle or vibration that resonates throughout the drive shaft, but it is only momentary and it can be repeated multiple times on end if the speed and rpms do not change.

Enough of the background... I took the truck to the dealership on April 28, and it was returned on May 9 with no resolution to the sound. The dealership, with whom I am very satisfied, kept the truck for an extended time simply to try other options. Ultimately, two bearings and a sleeve or slide gear in the transfer case were replaced yet the noise remained. Chevrolet miraculously discovered that it knew about the noise and that nothing could be done to remedy the problem. My dealership thought, as did I, that Chevrolet's position was a little outrageous. After all, if every single extended cab automatic tranny with the manual transfer case sold in the 2003 model year made the same noise, hundreds of thousands of people would be complaining.

Yesterday I spoke with Chevrolet's Factory Representative for the area. He said, and I quote: "The noise is a normal operating characteristic of that particular model. There is nothing we can do. We cannot re-engineer the entire vehicle."

I asked the rep if he would simply send me a letter confirming the noise is a "normal operating characteristic," and he refused. Not only did he refuse, though, he also advised that while the regional office handles all correspondence to customers, that office would also not issue a letter stating that the noise was normal.

I like my Chevrolet, for the most part. This single problem scares me though. Why is it that Chevrolet cannot stand behind its word or its product? In my perspective, this boils down to a $345 option (AutoTrac) that I chose not to have for the simple reason that electronics in a 4wd just lead to let-downs when you need them most. However, as an attorney, I cannot avoid the realization that if Chevy would have told me that my truck would make noise before I bought it, then I would most certainly have bought the AutoTrac. That is an unfair business practice, and if the noise is "normal," then certainly there are others with the same predicament which I face.

If you heard this noise, or if you had it in your truck, you would know it is anything but normal. The entire driveline resonates when the conditions are right. Even if Chevy is telling me the noise is not detrimental, the fact that my dealership has performed substantial repairs to the transfer case because it "did not feel comfortable with what it saw" makes me believe otherwise.

I know there are several other '03 1500 extended cab owners in this forum who have manual transfer cases. If any of you care to respond, I'm interested to know if you have ever experienced this problem and, if the noise has not been experienced, have you put your truck in the conditions which apparently always result in the noise?

As always, I appreciate the responses. I am trying to make up my mind right now on just how far I need to take this issue.

Shaners · May 30, 2003

Does the T-case shift lever vibrate while hearing the noise? Is it possible that the driveline resonation is coming through the boot area around the shift lever?

My '00 Silverado excab shortbed AutoTrac, made a bad resonation in the cab around 40 MPH while in OD. The way it was cured was the dealer reprogrammed my transmission so it wouldn't shift into OD until 45 MPH. There was actually a TSB about this problem, and GM changed the shift points on alot of these trucks when customer complained.

I don't know exactly why they stopped doing this, but they did, and I speculate it is because of EPA MPG numbers for the "fleet". My dealer told me that by changing the shift points, I could suffer in the MPG's.

You could buy a "Predator" programmer for about $400 and play with it to see if changing any of the operating parameters of your truck cures the problem. If it doesn't, then download the stock program back into your PCM and send the programmer back for a refund.

Good Luck and I hope your problem can be resolved...

SilveradoWV · May 30, 2003

My '00 Silverado excab shortbed AutoTrac, made a bad resonation in the cab around 40 MPH while in OD. The way it was cured was the dealer reprogrammed my transmission so it wouldn't shift into OD until 45 MPH. There was actually a TSB about this problem, and GM changed the shift points on alot of these trucks when customer complained.

This is the first thing I thought of when reading the original post, mine has the noise also but I never took it back to get re progammed. For some reason the noise pretty much went away when I switched from 245's to 265s.

jth7186 · May 30, 2003

Actually, the T-case lever doesn't vibrate any more than normal when the noise is heard; I've driven while holding the lever in my right hand and can't feel any extra vibration other than what I'd expect as ordinary road noise.

Odd, but true.

Right now I have the 265's that came with it. As you could expect, I'm very hesitant to spend money on the truck until GM comes up with a solution. I initially thought the dealership may have moved the shift points to keep it out of OD at the very low RPMs, but I'm not so sure now. If they did, it didn't resolve anything.

I have only noticed the noise while in OD, but I am tempted to believe that is true for the simple reason that the auto tranny will not stay in any other gear at that low of an RPM; it downshifts. That's probably the lock-up torque converter doing its job in OD -- keeping it in OD during what it senses as a "temporary" low RPM situation.

I'm baffled at the problem, but getting pi$$ed at GM. It's loud, it isn't like "road noise" or the "lugging" sound manual trannies make when the RPMs are too low. This is one weird animal.

mdub · May 30, 2003

jth7186,

My '03 with the manual 4x4 shifter does the same thing. I've taken it to the dealer twice, with only a little improvement. Their solution was to better isolate the shifter linkage by placing pieces of rubber tubing (actually rubber fuel line) between the shifter lever and linkage arm (also at the xfer case). It improved the condition, but the noise is still noticable. I'm very frustrated, but have given up on getting the noise resolved.

If it makes you feel better, I actually removed the 4x4 lever and linkage for about a week (when I installed a body lift). The 'mysterious' noise was gone the whole duration. This was somewhat comforting to me since it somewhat confirmed that there isn't a more serious rattle in the xfer case or tranny -- it's just mechanical noise that must be resonating through the shifter. It's very easy to remove the shifter linkage arm, so you may want to temporarily remove yours to prove that there isn't a more serious noise.

There's no question that the manual shifter and linkage design is very poor -- simple, but poor. Had I known about this problem, I would've ordered the Autotrac. Like you, I acually wanted the manual shift for reliability. Now look what we get instead. I would certainly be interested to know if your dealer has any better luck than mine in fixing the problem.

In any case, I have a much more serious problem -- I have the famous driveline clunk. It's most noticable when I slow down from highway speed, and then accelerate. The subsequent 1-2 and 2-3 upshift driveline "clunks" are extremely harsh and noticable. It's actually quite embarrassing when my 'Dodge' friends are riding in my brand new truck. I've read reports that this problem was fixed on the '03s... NOT true -- mine has it very bad at times. I hope to take it to the dealer next week, but don't have a lot of confidence that they can fix it.

Keep us informed on your progress. Good luck!

-Mdub

jth7186 · May 31, 2003

Finally, at least ONE other person has the same problem. I checked the lever again this afternoon to see if it vibrated or had a resonating shudder when the noise was most prevalent; it did not.

One weird thing is that when GM had the cold start knock problem and couldn't find a fix, customer assistance was quick to double warranties or give 100,000 mile warranties. But not in this case; no help from Chevy! No warranty, not even a component letter.

I really think this is a detrimental problem. Bearings and slide gears inside the t-case are being damaged, but no one knows what is causing the damage. It is easy enough to say "find what causes the noise, and you'll have what causes the damage," but the argument falls on deaf ears. Who knows!

Stepside Z · May 31, 2003

I am not sure what changes were made but my 99 Serria and my 01 Silverado both had t-case levers on the floor and I never had any of the problems you described.

sonjaab · May 31, 2003

GUYS......Remember the manual tras. case shifter only engages the trans. case. The front hubs are locked in by the electric/vac. solinoid (spl) not the lever.

I got a LD 2500 just for that autotrac. Not avail. on HDs.......................geo

Tfin · June 2, 2003

jth7186 I have an 02 Silverado extra-cab with the manual transfer case lever as well. Anyways while reading your initial post, my jaw almost fell on the floor. What you describe (as well as the conditions that produce the vibration/resonance) are exactly what happen on occation to my truck.

While going 45-50 or so up a very slight incline, and keeping the same speed or slightly increasing the speed, is when I notice this vibration of sorts in (what I assumed to be) my driveshaft. Your description fits my situation to a T!

I simply wanted to add my voice to your inquiry, and would ask that you pass on any additional information as you come across it.

jth7186 · June 7, 2003

Will do, Tfin. I do not have any information at this point though. I get the distinct feeling that I am being jacked around and GM is laughing about it...

nhkid28 · June 7, 2003

I have/had the exact same noise myself. I have also been told the same song and dance from the dealership and beyond.

What I did was change over my tranny fluid to Mobil 1 ATF and added a quart of Lubegard Red. This has almost eliminated the noise. I hear it very rarely now.

I did this under the suggestion that the noise was a torque converter chatter. He suggested that I add some Lubegard Red. I had the old fluid flushed and then put in the Mobil 1 ATF and the Lubegard.

Depending on your mileage try some Lubegard Red and see if it helps. I think its less than $10.00 and they have a web site to help find a local store. I changed my fluid because I had 35000 miles on it.

I hope this helps and good luck.