Bad trans or transfer case?

[Peeledpeas]

Have a 2005 GMC Yukon, 5.3 all wheel drive. Wife was driving it and suddenly it wouldn't go, she gave it more gas and it clunked and started to go but was now making noise. She pulled off the road and got a tow home. Turns out, now it's not holding in park, when shifted to reverse with brakes being held it makes a super loud grinding noise. Shift to drive with brakes applied and and there is no noise until you let off the brakes and the tires start to move. I'm suspecting a bad transfer case but do these symptoms match up? Also, when I went to drain the Tcase, there was way too much fluid in there, so it must also have a bad rear seal. Could this have contributed to failure? Thanks for the help.

 

[Sam Harris]

Damn. Sorry to hear this. I think I’d try to get it off the ground, and start moving wheels independently, and listening for noise with a mechanic stethoscope. If you can’t determine anything from that, might try the same while running, in gear, etc.. would be ideal while on a lift, but as long as you’re careful, can pretty easily be done on jackstands as well.

 

[strutaeng]

It's possible the transmission leaked into the T-case and transmission is now low on fluid? Have you checked the transmission fluid yet?

 

[Joseph Garcia]

@NickTransmissions

 

[V327839]

As I just swapped a tcase on my 04 Sub, the tcase and trans do not share fluid in any way. There is a breather type hole in the back of the trans where fluid can seep into the adapter. I found that out when I pulled my trans and fluid ran right out that hole. Don’t even know why it’s there. Anyway, the adapter is sealed both ends. If one of the gaskets leaked then you could have leaked tranny fluid. The tcase uses its own fluid, although I’m not sure what the awd tcases used, but they are self contained. A failed tcase, like mine, will manifest noise only while in motion. This is just my understanding from my experience.

 

[Peeledpeas]

I know the rear seal leaked into the Tcase. The reason I'm suspecting Tcase is because it doesn't hold it in park. I'm trying to figure out if the Tcase can fail and cause my symptoms because it feels like the park pawl is actually working and it also feels like it's going into gear. No noise in drive while holding brakes, super noisy in reverse while holding brakes. So, I'm thinking maybe something let go in the tacse that would do that.

 

[Peeledpeas]

Now that I think about, I forgot that we had a weird clunk that was like a bad ujoint a few weeks ago. But I wrote it off as imagining things when I didn't find any bad ujoints. I was hoping to find someone here that may have dug into one of these before.

 

[Jimmyy]

If it is a AWD the front and rear work like a open differential. If your rear wheels are on ice and the front on dry ground its possible for the truck to roll until a rear wheel catches a dry spot. You need to get all 4 wheels in the air and check it out.

 

[Jimmyy]

You could lift the back (block the front) and disconnect the drive shaft and spin the rear end to eliminate the rear-end.

 

[V327839]

I know the rear seal leaked into the Tcase. The reason I'm suspecting Tcase is because it doesn't hold it in park. I'm trying to figure out if the Tcase can fail and cause my symptoms because it feels like the park pawl is actually working and it also feels like it's going into gear. No noise in drive while holding brakes, super noisy in reverse while holding brakes. So, I'm thinking maybe something let go in the tacse that would do that.

The tcase can fail, as mine did. It’s the hole that gets work into the tail shaft housing and eventually leaks out all the fluid. Burns up the bearings fast. If you drain yours and there’s lots of fluid in it and it doesn’t look sparkly, then the tcase may be ok or just broke a chain maybe. Grasping at straws here. I narrowed it down by putting the rear on jack stands and the tranny in drive. I think you said you had awd so that may be a bit more difficult. For mine it was really easy to tell where the noises came from.