Transfer Case for 2003 Z71

[redbullf189]

Hey guys,
I just purchased my Tahoe last week and unfortunately I took it into the shop today to diagnose a sound that was common from around 25-40 MPH and went with the rotation of the wheels... We originally thought it was a bad wheel barring, so I had that replaced, along with the rear brake pads. Turns out, after spending the $ we spent, that the transfer case seems to be going out. Would it be cheaper to rebuild the current one on the Tahoe or purchase another one and have it installed?

If I rebuild the current one, it would require new fluid in the transfer case, along with the time to find out what exactly is wrong. They think it's a bad barring, but they're not sure... any ideas on that as well?

Also, which transfer case came in this vehicle for 2003? I saw different types and wasn't sure which type was put on from the factory during that year.

Any help would be greatly appreciated. Thanks

 

[taylorjm]

There's a round tag on the transfer case that tells you what model it is. I think there were a couple different models for that year, so you'll have to look on the case and see. I know my 03 transfer case is a NP246.

 

[Wake]

There's a round tag on the transfer case that tells you what model it is. I think there were a couple different models for that year, so you'll have to look on the case and see. I know my 03 transfer case is a NP246.

Also do some research on the model and check the interchange at the salvage yard if you go that route. Get the newest model year that will work with your vehicle.

I had a 2002 Trailbazer (NP226 I think) that I replaced the transfer case in. Prior to 2006 they had a weakness (small center carrier bearing) that was redesigned for 2006 production. 2002 - 2006 cases were compatible with my truck so I found an 06 version on eBay and discovered it was located at a local wrecking yard. Instead of buying it through eBay I called them and asked about an 06 transfer case. I ended up getting it for $100 cheaper (before shipping) than if I had bought it from eBay. So instead of $450 I ended up paying about $225.

 

[electro]

You could go under the truck and try to move the driveshafts side to side and up and down kinda thing... Looking for play as it comes out of the transfer case.

I suppose that would give you some idea as to how tight everything is inside. If there loose you can replace the seals. They look like really thin metal cylinders about maybe an inch and a 1/4 long and 1/16th of an inch thick. I don't know if that would make the noise you are referring too. Its possible. Although more likely those are bad and maybe caused something else to go as a result.

You could also take a peak at the fluid at the same time by removing the fill plug on the back side of the case. The GM AutoTrak II ( i think this is right) should be blue and should be just below the fill hole. I suppose you could look to see how the colour looks. If its a nice blue that would be good. or turning black/brown i guess would be bad.

Overall its not too difficult to remove from your truck and open it up. You take your drive shafts outs front and back, 2 straps each, drop them down and pull them out of transfer case. support transmission with jack and remove transmission crossmember. The lower it all a bit and remove transfer case to transmission bolts.

If you did it would cost you obviously fluid as well as a new seal when you put the case back together its comes apart in two pieces. RTV sealant that is. Probably a good idea to replace seal between transfer case and transmission. Its right there when you remove transfer case.

If you want the cheapest route I would presume if you do everything correctly and don't cause further damage...take if off yourself and replacing a few bad internal comments would be far less costly then a new one.

 

[redbullf189]

Thanks for all the advice, I'll definitely take a look at it this evening... it is definitely an NP246, so I'll try and find one somewhere around here. My friend who's a mechanic said it drives and sounds like it's a barring starting to go bad, so we're going to look at the fluid later and see if there's any metal in it.

 

[redbullf189]

So we looked at it and the fluid was pretty low, about half a quart. I'm thinking that may have damaged something in the transfer case.

The noise is a grinding noise, metal on metal, that speeds up and slows down as the car does... it does it pretty much 20mph and above. Is this the transfer case or potentially the front differential? I'd hate to replace something that's not broken. If it helps, it does it in 2WD.

 

[electro]

I think the bottom line is if you suspect something in the transfer case but are not positive you really have two choices. 1, open it up or 2, dont.

Also, check the diff fluids!

You could put the truck on a lift or jack stands and have someone turn the truck on and put it into gear and slowly accelerate. While doing this you could put your hands to the transfer case or differential and feel/listen or use a stethoscope or a big screw driver. Dont get your hands caught in the driveshafts!! haha. ouch. or let the truck fall off the stands. more ouch.

 

[redbullf189]

Well the front differential fluid was nasty, looks like it was mixed with water, I'm going to drain and replace the fluid to see what happens.

 

[tenntahoe]

I know this is an old thread, but did you diagnose your problem? My tahoe is making a similar noise and I'm pretty sure it is coming from the transfer case.