Looming transmission trouble?

[Teejay123]

Need some help if anyone has experienced this or has any ideas. . .

I have a 2017 GMC Yukon XL, 127000 miles, 5.3L.

I had a quite hard shift from 1st to 2nd gear a couple days ago. Starting yesterday I’m hearing an intermittent buzzing/humming/pump type sound as I’m driving. It starts just 1-2 seconds before the transmission is going to switch from 2nd to 3rd and then stops a second or two after the shift (same sound at 3-4th and 4-5th). It sounds like it is coming from under the car ( I think). Almost like a revving sound.

The transmission has had some issues in the past. Last March I had to replace the Automatic transmission control valve body spacer plate because one of the little plastic balls wore down and got stuck. The car would not go into drive and I had to back it up to my house from about a mile away. I also replaced the gasket, filter, and fluid at that time.

Any thoughts about what this might be would be helpful. I’d rather try to diagnose/repair myself before (rather than) going to the shop. I’m sure the spacer plate issue would have cost me thousands so I want to avoid a huge expense, if possible.



Thanks

 

[Teejay123]

Also, there was some shuttering, like it was trying to get in gear but was delayed, at like 40mph as well.

 

[Miami-Dade]

@NickTransmissions

 

[NickTransmissions]

Need some help if anyone has experienced this or has any ideas. . .

I have a 2017 GMC Yukon XL, 127000 miles, 5.3L.

I had a quite hard shift from 1st to 2nd gear a couple days ago. Starting yesterday I’m hearing an intermittent buzzing/humming/pump type sound as I’m driving. It starts just 1-2 seconds before the transmission is going to switch from 2nd to 3rd and then stops a second or two after the shift (same sound at 3-4th and 4-5th). It sounds like it is coming from under the car ( I think). Almost like a revving sound.

The transmission has had some issues in the past. Last March I had to replace the Automatic transmission control valve body spacer plate because one of the little plastic balls wore down and got stuck. The car would not go into drive and I had to back it up to my house from about a mile away. I also replaced the gasket, filter, and fluid at that time.

Any thoughts about what this might be would be helpful. I’d rather try to diagnose/repair myself before (rather than) going to the shop. I’m sure the spacer plate issue would have cost me thousands so I want to avoid a huge expense, if possible.



Thanks

Sounds like torque converter failure. Sudden onset of hard shifts as well as shuddering are tell tale signs. Put a bidirectional scan tool on it and take for a short drive (if you dont have such a scan tool, buy one - no DIYer should be without one). Bring up live trans and TC data. Look at duty cycle and TCC slip speeds when the trans applies the converter clutch when cruising. If slip speeds are high when duty cycle is high, you have confirmed the TC clutch is slipping when it should not be.

Usually this means a rebuild will be required very soon.

Visit my 6L80 Information thread for more details, tech resources, video instructions, diag info, etc - link is in my signature line.

 

[jaxscuby]

what Nick said...

but i also had shudder issues and replaced my torque convertor and the transmission shifts smoothly
as intended..also had it remapped for lock-up in 5 & 6 th gears..

 

[Teejay123]

That is what I was afraid of hearing. I read elsewhere some people suggesting that a fluid flush/replacement could possibly offer some relief.

I’m definitely not equipped to pull the transmission so I would need to have a shop do it and I’m sure that is an astronomical sum of money. Is it worth it to spend that money on this truck that has been pretty problematic, by comparison to other vehicles I’ve owned? I don’t know about that.

Thank you

 

[Teejay123]

Sounds like torque converter failure. Sundden onset of Hard shifts as well as shuddering are tell tale signs. Put a bidirectional scan tool on it and take for a short drive (if you dont have such a scan tool, buy one - no DIYer should be without one). Bring up live trans and TC data. Look st duty cycle and TCC slip speeds when the trans applies the converter clutch when cruising. If slip speeds are high when duty cycle is high, you have confirmed the TC clutch is slipping when it should not be.

Usually this means a rebuild will be required very soon.

Visit my 6L80 Information thread for more details, tech resources, video instructions, diag info, etc - link is in my signature line.

Thank you for the information. I appreciate the help

 

[Teejay123]

what Nick said...

but i also had shudder issues and replaced my torque convertor and the transmission shifts smoothly
as intended..also had it remapped for lock-up in 5 & 6 th gears..

I will check with some shops on this. Thanks for the top

 

[Teejay123]

Hi all,

Thanks again for the help. I got a quote on the transmission to be rebuilt with a Billet Torque converter- $4500/ 18month 18k mile warranty

Or

$5100 for a remanufactured transmission and a 5 yr warranty

Those prices are at the bottom end of what I was expecting so it might make sense if I can reasonably get another 5 years of good service out of the truck.

Is getting to 200k on this 5.3L engine a reality without other multi thousand dollar fixes?

Thanks

 

[NickTransmissions]

Hi all,

Thanks again for the help. I got a quote on the transmission to be rebuilt with a Billet Torque converter- $4500/ 18month 18k mile warranty

Or

$5100 for a remanufactured transmission and a 5 yr warranty

Those prices are at the bottom end of what I was expecting so it might make sense if I can reasonably get another 5 years of good service out of the truck.

Is getting to 200k on this 5.3L engine a reality without other multi thousand dollar fixes?

Thanks

No REMANS! None of them are any good and you'll be likely bringing it back for warranty (possibly after it strands you). Would suck if you paid more money for less of a product.

Get your existing transmission rebuilt with a billet torque converter - check with the shop re the parts and procedures list against those lists found on page 1 of my 6L80 Information thread (link is in my signature line).

I have 190k on my 2009 GMC Sierra and engine is still going strong. I may rebuild a core LH6 with a non-DOD cam later this year to have it ready to go in case the one in the truck now sh!ts the bed but it currently seems fine.

 

[jaxscuby]

Planning on building a non dod replacement motor..currently at 197k. Also a replacement 6L80. But also researching 10L80 swap.