MAJOR driveline noise, no fwd or reverse - WTF?

[cdig]

I just picked up a 2004 GMC 2500HD, 6.0L AT. Bought it at auction for cheap (it was a theft recovery), figured i'd take a chance on it. Engine runs good, but when i put it in reverse or any drive gear, in 4wd or 2wd it doesn't even try to move, just get a very loud banging/crunching/grinding/gear stripping kind of noise... looking under the truck while it's in gear, the driveshaft isn't moving so it's not the rear diff. I'm wondering if anyone has any thoughts as to whether this would just be the tcase mainshaft broken or could it be the transmission main shaft?

My understanding is that the 4L80e shaft is pretty much bullet proof, so I'm leaning towards replacing the tcase first. Is there anyway I can diagnos this without taking the tcase out? I can try replacing the tcase first as i have a used one, but if I can diagnos it prior to doing so would be much better.

Thanks for any insight!

C.

[gregory5000]

I have never done anything like that before, but It sounds like you are on the right track with thinking it is the transfer case. Like you said that transmission is bullet proof. How many are on the truck?

[cdig]

214,000km (~132000 miles) on it, but like i said it's a theft recovery so someone likely beat the hell out of it.

[RUSHNBOBO]

Here's some complaints from GMC's complaint dept.

The contact owns a 2004 GMC sierra 2500 hd. The contact performed routine maintenance on the vehicle and observed that the transfer case (4 -wheel drive) contained pinholes, which led to an internal fluid leak. The transfer case fluid level was completely empty. The locking clip failed, which contributed to the failure. The vehicle was taken to an independent transmission shop and the technician replaced the locking clip. The failure mileage was 120,000 and current mileage was 126,000.


The contact owns a 2004 GMC sierra. The contact was towing a boat and discovered there was transfer case oil splattered all over the boat. The vehicle was taken to an independent repair facility where he was informed that there was a hole in the transfer case. A new transfer case and pump housing were installed at the independent repair facility. The failure did not recur. The failure and current mileages were 82,000.

Check the fluid level in the T case, and signs that it may have been leaking.

[RUSHNBOBO]

Originally Posted by cdig

I just picked up a 2004 GMC 2500HD, 6.0L AT. Bought it at auction for cheap (it was a theft recovery), figured i'd take a chance on it. Engine runs good, but when i put it in reverse or any drive gear, in 4wd or 2wd it doesn't even try to move, just get a very loud banging/crunching/grinding/gear stripping kind of noise...

Thanks for any insight!

Will the truck roll or move at all with transmission in neutral and transfer case engaged ? if so what do you hear ?

[truckdude239]

you can always remove the tcase and serpater the case and check the inside

[cdig]

so i started taking the tcase out, pulled the rear drive shaft off and spun it, makes very much the same sound that i was hearing before when i put it in drive! pulled the drain bung to drain it before separatign the tcase from the trans adapter... low and behold there was so much shrapnel in the case that it blocked the drain hole! stuck a screw driver in it to work it around and i'm sure half the guts of the tcase fell out. I think I'm on the right track

Thanks for the suggestions guys. I'll let you know if the tcase fixes it totally.

[RUSHNBOBO]

Originally Posted by cdig

so i started taking the tcase out, pulled the rear drive shaft off and spun it, makes very much the same sound that i was hearing before when i put it in drive! pulled the drain bung to drain it before separatign the tcase from the trans adapter... low and behold there was so much shrapnel in the case that it blocked the drain hole! stuck a screw driver in it to work it around and i'm sure half the guts of the tcase fell out. I think I'm on the right track

Thanks for the suggestions guys. I'll let you know if the tcase fixes it totally.

Call Gmc and see if they will repair it .....even if your not the original owner they may do it if you cause enough stink. Cite the examples on their own web site about the case leaking problems due to factory defects and see what they say.....you got nothing to lose. I got a complete head gasket repair from Toyota by doing the same thing and I was the 3rd owner with 150,000 miles.

[cdig]

wish i could, doesn't look like it's been leaking from the case. I've seen one of those before tho, wish i would have known that GM covers them.

[RUSHNBOBO]

Probably got to bite the bullet then.................