2007 Gmc Sierra Transmission Issues

[z7107sierra]

Hello Everyone..

 

I'm new to the site & I'm hoping to get an idea on whats going on with my truck.

 

I have a 2007 GMC Sierra z71....I have 144,000 miles on the truck it still runs new & I'm very happy with it..I've always had it serviced by my dealer..I've had the transmission flushed a couple times so far..my most recent flush with dexron 6 was at 140,000..was told old oil looked fine & wasnt burnt at all..I do not "abuse" any of my trucks..

 

Friday afternoon one of our Excavators got stuck on a jobsite 30 miles out in the country..I hurried out there as fast as I could before someone tried to get it out it their way & make the situation worse..I passed 5-6 cars & I was in excess of 75mph..It ended up being a long day..I noticed though that when I stopped then turned onto the dirtroad to the jobsite & I started speeding back up & when the truck shifted from 1st to 2nd all was fine but when it shifted from 2nd to 3rd I head almost like a small groan while it was changing gears..I ignored it but on my way back home that night I listened for it & it was still there..It'll only do it when the Transmission is shifting from 2nd to 3rd..You can hear it & feel it alittle bit thru the floor..But you only hear it when you take off slowly..If you take off at normal speed for most you never hear it.. I'd like to beleive that there's no way driving hard that one time screwed up my Transmission...

 

Its still doing it today but it only does it while its shifting from 2nd to 3rd & you accelerate slowly..I will take it to my dealer but they'll tell me its normal & it wont get figured out till my 8th trip down..My Oil looks & smells fine..

 

Any idea's?

[z7107sierra]

One thing I should mention..The Groan only lasts for maybe a second while its changing gears from second to third then its gone & it doesnt make any noises while its downshifting from 3rd to 2nd..

[jf781]

Have you checked the fluid since they had the tranny serviced? Possible they might not have filled up enough or too much? Fluid still smell ok?

[redsled2007]

I believe that there’s a TSB about cleaning the MAF sensor to solve this kind of problem.

Also I think there was a discussion about this in this forum about a couple weeks ago.

[z7107sierra]

Checked Fluid today & it was at the correct level with the truck running & in park...Oil looked & smelled new...

 

I'm almost leaning towards its the torque converter making the groan..Its making it while its shifting into 3rd once its in 3rd no noise..Or if your speeding up fast it wont make any noises & it shifts fine...If you nearly floor it..It shifts fine also..I took it on a 3 hour drive on the highway today Trans. temp never got above 151 degrees..Seems to be running fine..But I"m alittle worried about someday of something falling apart on me...I'm contemplating having the transmission rebuilt..I'd like to run this truck to 250k if I can..