High pitch ATF grinding sound when cold shifting from 2nd to 3rd gear

[jemmie]

I have a 2005 Envoy 4WD I-6 with 105,000 miles or so. Just this week, upon a cold start in cold weather (<35F or so), there's a high pitched grind sound for about a second when shifting from second to third gear. After AT warms up, it goes away. I use Mobil 1 ATF, have auxillary ATF cooler, etc. etc. etc.

Is this something I should be concerned about? What's this mean?

Thanks!

 

[jrSS]

Your supposed to be using dexron vi. How many quarts did you add when tranny fluid service was done?? Did u do a pan drop and filter change or a whole flush?? I would start by putting the correct fluid in. And Merry Christmas btw.

 

[Wooluf1952]

From what I've read, Mobil 1 ATF meets Dexron III specs. IIRC, Dexron VI wasn't required until 2006. So going to Dexron VI is an up-grade in fluid, it isn't required for a 2005.

 

[jemmie]

That's my understanding as well. I also have inline ATF filter. I sometimes tow a 20' aluminum boat and 25' travel trailer with it (not at the same time).

So, leaving right/wrong ATF aside, what's the high pitched grinding sound mean?

Ignore it? Be paranoid about it? Sign of failure but nothing I can (or should) do until it fails?

 

[Wooluf1952]

Others will jump in, but, IMHO, if you just ignore it, Murphy's Law says it will fail completely half way home on a Sunday night with the boat in tow.
Also, the next time you need ATF, go with the Dexron VI. I noticed much better shifts when I did a pan drop and used the VI.

 

[jemmie]

Others will jump in, but, IMHO, if you just ignore it, Murphy's Law says it will fail completely half way home on a Sunday night with the boat in tow.
Also, the next time you need ATF, go with the Dexron VI. I noticed much better shifts when I did a pan drop and used the VI.

I might just do that. I looked and I flushed ATF 40,000 miles ago, which is probably more than long enough for how much towing I do with this.

What brand Dexron VI should I use?

 

[Wooluf1952]

I used Castrol, but anything that meets Dexron VI specs should be fine.

 

[jemmie]

I drained and flushed ATF and replaced with Castrol Dexron VI and the noise went away, and this morning was the coldest day of the year. I suspect it's the new ATF rather than Dexron VI that fixed the problem. Thanks all.

On a side note, my observation is that the life of all the fluids in this vehicles need to be watched like a hawk. I sent in my oil (Mobil 1) for a test after 7500 miles and the result was essentially that it was crap, so I shortened it to 5000 mile cycles. If I don't change my transfer case fluid every couple of years, the vehicle hesitates regularly while moving. And the ATF I changed out was Mobil 1 and only had 40,000 miles on it, and I have auxillary ATF cooler as well as inline Magnefine filter.

 

[Bartonmd]

I'm having the same thing happen, and also have a thread on it. It hadn't happened before the tune, but then again, it's had 10k miles since it was this cold, so who knows. Mine has ~100k on it, and the fluid was changed at 50k with Dex 6.

I took this video yesterday. It normally does it worse on the 1-2, but the 1-2 was fine this time. It did do it on the 2-3, though. You have to have the volume really high to hear it, though (and ignore the road noise on acceleration).

[video=youtube;wW2dX-bUG4M]http://www.youtube.com/watch?v=wW2dX-bUG4M[/video]

I was planning on changing the fluid (and T-case and both diffs again) this winter, too, so no big deal there... I am going to pull the tune off, tonight, and see if it's something that makes it happen or happen worse, or doesn't affect it at all.

Mike

 

[jemmie]

Same exact noise as mine. Flush ATF and it's probably fixed.

 

[Bartonmd]

Did new ATF and yep, fixed it..

Mike

 

[Sparky]

Odd I've never heard that sound, even when I first got my truck at 112k and the fluid was really old. 169k now.

 

[Bartonmd]

My Dad said it sounded like light clutch chatter, and it would probably last forever like that, but a fluid change fixed it, so why not?

Mike