Concerned with Transmission. Thoughts?

[Krmnnghia]

Could use some advice...07 Yukon Denali XL, original 6spd trans with 104k miles. Unknown trans service history but vehicle was very well taken care of overall when I acquired it at 102k miles. Just did the front and rear dif and the transfer case fluids last week which i believe were probably about due judging by the color of the fluid. No chunks came out just some really fine shavings as I would expect. Magnets looked good.

Drove 10 hours this weekend and noticed on occasion if doing say 60mph and I needed to quickly pass someone at near WOT, it will downshift several gears with a very loud and violent bang. If I ease in to it, it downshifts smooth as silk. Upshifts 1-2 & 2-3 are sometimes harsh at very slow speeds but nothing too concerning. I also have quite a delay from reverse to drive on occasion...roughly 1.5 seconds after putting it in "D" it will finally shift. Which of my concerns are normal complaints of the 6spd? The different forums I checked concerning the 6l80 are all over the place on these issues it seems with some having them since day 1 of their new vehicles. I plan on doing a complete fluid transfer and filter service soon but will hold off if anyone thinks I have bigger problems. Thanks

 

[swathdiver]

Change the fluid. The transmission learns how we drive and different styles can cause it to act funny, it also adjusts for wear. It'll operate a lot nicer if you get a tune for your truck from BlackBear. As for the downshift bang, that's a new one for me. Maybe others will have knowledge of that.

 

[Krmnnghia]

Thanks swathdiver. I will try and get to it in the coming weeks.

 

[kbuskill]

I was unaware of any 6 speed transmissions in 07.... I was under the impression they didn't put 6l80e in until 09.

 

[swathdiver]

Denalis had the 6L80 since 2007. The regular models got it in 2009. The 6L90 became available for the 2500s in 2008.

 

[Krmnnghia]

So something interesting I have noticed recently. It has been 20-30 degrees in the morning lately when I take my son to school. Twice in the last 10 days, after a brief 3-4 minute warm up, the first time the vehicle goes from 2nd to 3rd I am getting the same strange clunk from what sounds like the rear. My takeoffs and speed are very slow(under 15mph) so its not like I am hammering it. After that clunk I won't hear it again for the rest of the day and shifting up/down is normal.

Possibly related although I doubt it...I did the motor mount test and I think my driver side is bad. Engine torques to the passenger side an inch or so.

Thoughts?

 

[PG01]

So something interesting I have noticed recently. It has been 20-30 degrees in the morning lately when I take my son to school. Twice in the last 10 days, after a brief 3-4 minute warm up, the first time the vehicle goes from 2nd to 3rd I am getting the same strange clunk from what sounds like the rear. My takeoffs and speed are very slow(under 15mph) so its not like I am hammering it. After that clunk I won't hear it again for the rest of the day and shifting up/down is normal.

Possibly related although I doubt it...I did the motor mount test and I think my driver side is bad. Engine torques to the passenger side an inch or so.

Thoughts?

Bad Motor mount would go more than an inch.... how are your u joints?

 

[Shaw520]

I would say U-joint or slip yoke.

 

[doc_sun]

Gonna follow this one. I'm getting the occasional clunk when cold as well. Also a little extra vibration under acceleration as well lately. Might be paranoia hearing there tho...

 

[Krmnnghia]

Gonna follow this one. I'm getting the occasional clunk when cold as well. Also a little extra vibration under acceleration as well lately. Might be paranoia hearing there tho...

I found this thread and the last two comments are interesting... http://www.tahoeyukonforum.com/threads/6l90e-problems.80106/page-2

I’m going to take a video of my motor doing the brake/rev test and maybe the folks here can at least tell me if I have a motor mount problem.

 

[doc_sun]

Yeah. I'll check my mounts. Good call on that old thread... slipyoke possible in my case.

 

[Krmnnghia]

Well here is a video from two different angles I took. Thoughts?

 

[PG01]

That is def broken, normally you just hold the brakes and give it gas, but yeah, thats broken.

 

[PG01]

Silver area I circled in red is the heat shield over the mount. I would do that first and see if you noise goes away. I would then look at your ujoints and slipyoke and eevn the pinion bearing if you feel like noise is coming from the rear. Any leaking from the pinion seal?

 

[Krmnnghia]

Thanks guys. Being that its in the mid 30's outside I will have to wait until it warms up to do the mount. I need to look in to the H2 mount as I hear those last longer.

The old saying...when it rains it pours. I drove to Napa today, parked, went in, came back out and the truck wouldn't start. Wouldn't even try. Got a jump and was on my way but seriously WTH. Now to track down that issue.

 

[rook]

Well here is a video from two different angles I took. Thoughts?

Damn... at least it’s pretty clear what the issue is!


Sent from my iPhone using Tapatalk

 

[Yukonjoe2001]

Could use some advice...07 Yukon Denali XL, original 6spd trans with 104k miles. Unknown trans service history but vehicle was very well taken care of overall when I acquired it at 102k miles. Just did the front and rear dif and the transfer case fluids last week which i believe were probably about due judging by the color of the fluid. No chunks came out just some really fine shavings as I would expect. Magnets looked good.

Drove 10 hours this weekend and noticed on occasion if doing say 60mph and I needed to quickly pass someone at near WOT, it will downshift several gears with a very loud and violent bang. If I ease in to it, it downshifts smooth as silk. Upshifts 1-2 & 2-3 are sometimes harsh at very slow speeds but nothing too concerning. I also have quite a delay from reverse to drive on occasion...roughly 1.5 seconds after putting it in "D" it will finally shift. Which of my concerns are normal complaints of the 6spd? The different forums I checked concerning the 6l80 are all over the place on these issues it seems with some having them since day 1 of their new vehicles. I plan on doing a complete fluid transfer and filter service soon but will hold off if anyone thinks I have bigger problems. Thanks

Beware of flushing your trans. Some times that could dislodge gunk/small pieces of debris that could clog somewhere further down and speed up the death of your trans. I'd line up another trans just in case

 

[Krmnnghia]

Beware of flushing your trans. Some times that could dislodge gunk/small pieces of debris that could clog somewhere further down and speed up the death of your trans. I'd line up another trans just in case

This is like the old wives tale that just won’t die. I Will flush the trans through the stock trans lines and fill with new until the color changes. No old school flushes here...

 

[Shaw520]

Yup,..thats the right way to do it,.. Ive done numerous old trannys like that without issue, old wives tale.

 

[Yukonjoe2001]

I'm sure there has been situations where flushing has made it worse,sometimes you get lucky. I've had and seen cases,where people have by simply changing there fluid and filter have had transmission failure. For that reason,I don't ever change mine. never any problems and I haven't even checked mine in 28,000 miles. Just my beliefs