2003 Chevrolet Silverado tranny or transfer case.

[jhol]

Ok Here is the details, any advice would be great

2003 Chevy Silverado 1/2 ton extended cab 175,000 miles

5.3 litre v-8

The other day at work I went to back out of my parking spot and put it in gear and it immediately made a grinding noise in the back end, it even felt like it caught and jumped a bit as I went to back up. So I backed up and put it in drive and the grinding noise continued. So I took it into my local mechanic here thinking it was the rear end. As best as he could figure it was the rear differential so we where going to replace the whole works. He gets it opened up and says everything looks great, he puts two new seals in, redoes the u brackets and it still makes noise.

He thinks now it is either coming from the transmission or the transfer case, not sure which, probably start with the transfer case. Does anyone have any experience with either of these.....

As far as symptons goes, it makes a grinding noise, especially in lower gears, sometimes better sometimes worse. Only really made the truck jump a little going in reverse the first time. The service 4wd drive light came on the first time and has not come on again after that. Also once in a while, and this has happened for awhile, I will start the truck and it will show the selector for the drive with a red dot, not selected in 2wd or 4wd or 4wd low, not sure if that is related or not. It might make a little more noise when turning corners but kind of hard to tell. Also sometimes you can hear a part spinning at a high rpm before shifting then it kind of spins off and gets a little quieter....

Any thoughts or advice would be appreciated...

Thanks

[Jeremy airjer W]

Sounds like maybe the encoder motor in the transfer case is stuck somewhere in between four and two wheel drive.

If its grinding than there should be evidence of the grinding in the fluid. Drain the transfer case fluid into a clear container and see if it sparkles.

You could also pull the encoder motor and see if the grinding stops. I think the default position is two wheel drive with it removed but have never really checked.

[BartmanMN]

Not sure why you would hear the noise in the back it it was partially between 2 and 4, but I'm not an expert. When you click it on 4 wheel hi, do you hear it lock up the front end?

Transfer case fluid sounds like a good starting point.

[jhol]

Well an update,

Went and talked to the mechanic the day before yesterday, he says he is 90% sure it is the transfer case. So we found one out of a wreck and away we go. I go to pick it up and he says it is done but take it for a drive. He thinks there is still a little noise under there. So I drive it and to me it sounds exactly the same. So I feel like I am back to square one.

So far this is what we have done

-Pulled apart rear end and inspected gears, repacked seals

-Replace u joint

-Installed a new transfer case

So does this mean I am sitting on a ticking time bomb for a transmission. Obviously after he was done yesterday I said I would just take it and see what happens. Seems to drive fine, just loud underneath...

[jhol]

Oh by the way seems to shift between 2wd and 4wd with no problem...

and so everybody knows I do not mind putting the money into this truck, it is going to be with me for a long time, engine runs great and I have had it since 14,000 miles and less that a year old. I love it, just want to figure out if it is going to leave me stranded sometime soon...

[Jeremy airjer W]

so here's what I would do next.

Get all four tires off the ground. Run it in drive. Do you hear the noise?

If yes pull the rear drive shaft. Do you hear the noise.

If no than its in the rear end.

If yes pull the front drive shaft. If its still there and the transfer case is "new" than it must be in the transmission since everything else has been eliminated.