Clunking Sound In Transfer Case?

ZBrink · August 20, 2009

This is a 2000 GMC Yukon XL 4x4 with 157k on the clock. With the vehicle completely stopped and my foot firmly on the brake, I will shift either into or out of Reverse and the clunking sound is made. This sound is NOT made when shifting into Drive, 3, 2, or 1.

On a lift at my mechanic, it appears to be coming from the transfer case. There is also some "fluid" on the outside of the case but no apparent drip to leak per say.

Any ideas? My mechanic doesn't know...

Thanks,

Zack

Pilot12 · August 20, 2009

This is a 2000 GMC Yukon XL 4x4 with 157k on the clock. With the vehicle completely stopped and my foot firmly on the brake, I will shift either into or out of Reverse and the clunking sound is made. This sound is NOT made when shifting into Drive, 3, 2, or 1.

On a lift at my mechanic, it appears to be coming from the transfer case. There is also some "fluid" on the outside of the case but no apparent drip to leak per say.

Any ideas? My mechanic doesn't know...

No idea....does the transfer case operate normally? IE. into and out of 4 low and 4 hi and 2 hi? Does the 4WD act normal? Do you get the same noise whether or not you're in 4WD? If the noise is really coming from the transfer case and not the tranny, seems like there should be some symptom there too. Maybe it's the play in one of the u-joints?

jf781 · August 20, 2009

I've heard other people talk about this as well, can't remember the exact solution though. Have you tried to grease the carrier barrier for the drive shaft? It was either that or dropping the drive shaft and greasing up the slip yoke for where the drive shaft connects to the t-case. I think someone mentioned that this is where the clunk was coming from here or another forum...

I'm sure someone else can verify if that is right or way off.

cliobogger · August 20, 2009

sounded like a u joint to me. but id have to be there to actually hear it...is it possible to take a video of it and post it up here?

ZBrink · August 23, 2009

sounded like a u joint to me. but id have to be there to actually hear it...is it possible to take a video of it and post it up here?

My mechanic says that it is not the U-joints...He stated that they are fine.

ZBrink · August 23, 2009

No idea....does the transfer case operate normally? IE. into and out of 4 low and 4 hi and 2 hi? Does the 4WD act normal? Do you get the same noise whether or not you're in 4WD? If the noise is really coming from the transfer case and not the tranny, seems like there should be some symptom there too. Maybe it's the play in one of the u-joints?

I will check on the 4WD HI and LO and report back...Thanks!

ZBrink · August 25, 2009

No idea....does the transfer case operate normally? IE. into and out of 4 low and 4 hi and 2 hi? Does the 4WD act normal? Do you get the same noise whether or not you're in 4WD? If the noise is really coming from the transfer case and not the tranny, seems like there should be some symptom there too. Maybe it's the play in one of the u-joints?

I will check on the 4WD HI and LO and report back...Thanks!

I was able to switch in and out of AWD, 4WD HI and LO just as normal. I also drove a short distance in all three. They all made the normal metal-to-metal engagement sound.

There is a definite and slightly loud clunk only when going in and out of reverse. And it sounds like it is coming directly from the transfer case. With my friends foot firmly on the brake, he shifted both in and out of reverse as I lay under the case. The clunking sound is made as the drive shaft shifts slightly during both the engagement and disengagement of reverse.

Does that help??

Pilot12 · August 25, 2009

I was able to switch in and out of AWD, 4WD HI and LO just as normal. I also drove a short distance in all three. They all made the normal metal-to-metal engagement sound.

There is a definite and slightly loud clunk only when going in and out of reverse. And it sounds like it is coming directly from the transfer case. With my friends foot firmly on the brake, he shifted both in and out of reverse as I lay under the case. The clunking sound is made as the drive shaft shifts slightly during both the engagement and disengagement of reverse.Does that help??

Did you take the fill plug out of the TC and check the level isn't a little low? You mentioned evidence of a slow seepage. It should be just below the bottom of the hole. You might consider draining at least a little fluid and checking for metal, don't forget to fill it back up.

If you're sure it's the transfer case, but it operates normally, I'd probably try to live with it for a while to see if the symptoms change, then take it to a different mechanic.

1 sic chv · August 27, 2009

its most likely the play in the yoke go out side and shake ur bed hard and you hear a noise if its sounds like the same noise it normal play

P71_CrownVic · August 27, 2009

This is a 2000 GMC Yukon XL 4x4 with 157k on the clock. With the vehicle completely stopped and my foot firmly on the brake, I will shift either into or out of Reverse and the clunking sound is made. This sound is NOT made when shifting into Drive, 3, 2, or 1.

On a lift at my mechanic, it appears to be coming from the transfer case. There is also some "fluid" on the outside of the case but no apparent drip to leak per say.

Any ideas? My mechanic doesn't know...

Thanks,

Zack

NORMAL...or so GM says.

That was the response I got when I brought my truck to the dealer for the EXACT same thing. GM has an information bulletin that they distribute to the dealers saying that if someone comes in with this issue, it is the normal lash between the gears.

I am trying getting mine fixed at another dealer tomorrow.

ZBrink · August 27, 2009

This is a 2000 GMC Yukon XL 4x4 with 157k on the clock. With the vehicle completely stopped and my foot firmly on the brake, I will shift either into or out of Reverse and the clunking sound is made. This sound is NOT made when shifting into Drive, 3, 2, or 1.

On a lift at my mechanic, it appears to be coming from the transfer case. There is also some "fluid" on the outside of the case but no apparent drip to leak per say.

Any ideas? My mechanic doesn't know...

Thanks,

Zack

NORMAL...or so GM says.

That was the response I got when I brought my truck to the dealer for the EXACT same thing. GM has an information bulletin that they distribute to the dealers saying that if someone comes in with this issue, it is the normal lash between the gears.

I am trying getting mine fixed at another dealer tomorrow.

Please keep us posted on what you find out. Thanks!

P71_CrownVic · August 28, 2009

Please keep us posted on what you find out. Thanks!

Well, I was at the (different) dealer today and they told me the same thing. It's normal. That being said, they did offer to grease my slip yokes (probably because I have a GMPP extended warranty).

Still makes the noise....

ZBrink · September 1, 2009

Please keep us posted on what you find out. Thanks!

Well, I was at the (different) dealer today and they told me the same thing. It's normal. That being said, they did offer to grease my slip yokes (probably because I have a GMPP extended warranty).

Still makes the noise....

Interesting...Well my truck is well out of warranty so I am waiting for the local transmission shop to have a free lift. Once they have one available, the shop is going to throw mine up on it to see if they can determine anything.

Gryphon · September 2, 2009

Funny, I noticed the exact same thing today just AFTER I dropped my driveshaft and re-greased the thing. Maybe I just never noticed it cause I usually have the stereo up but mine clunks going in and out of reverse too. I haven't checked the T-case fluid level but that makes sense. Definitely isn't the slip yoke.