Jump to content

6 speed failure


Recommended Posts

Does the pump grinding into the case happen with the 8L90 when it has the factory Mobil 1 fluid that is hydroscopic? 
 
My 8l90 shifts fine but I only have 10k miles on truck. My truck was built 12/2017 which means it has the older Mobil 1 fluid that is hydroscopic? 
 
I haven't received any notice to have the fluid exchanged to the newer type. That is a TSB, and you have to prove your trans is shuddering correct?

There has been no 8 speed failures like this in my shop. 6 speeds all day long.


Sent from my iPhone using Tapatalk
  • Like 1
Link to comment
Share on other sites

I'm not sure. Could you explain it a little bit more?

I’m 90% sure you’re hearing the vacuum pump cycling which they all do. That constant snapping noise, it’s very clear in drive thrus or against walls? That’s the vacuum pump. Totally normal. Rest easy friend. Hope this helps you enjoy your tuck a little bit more!

-GM Tech


Sent from my iPhone using Tapatalk
Link to comment
Share on other sites

15 minutes ago, tlaw91 said:


I’m 90% sure you’re hearing the vacuum pump cycling which they all do. That constant snapping noise, it’s very clear in drive thrus or against walls? That’s the vacuum pump. Totally normal. Rest easy friend. Hope this helps you enjoy your tuck a little bit more!

-GM Tech


Sent from my iPhone using Tapatalk

Thanks, I appreciate it.

  • Like 1
Link to comment
Share on other sites

On 2/5/2020 at 9:33 PM, tlaw91 said:


There has been no 8 speed failures like this in my shop. 6 speeds all day long.


Sent from my iPhone using Tapatalk

Well this is depressing, I have the 6 speed. I figured it would be the more reliable of the two.

 

I have 47,000 miles on it now...I've done two transmission services (one pan drop and the other just a drain and fill through the dipstick). I do get a slight shutter occasionally going up hills on the highway, since new.

 

Good to have you on the site, we need more GM techs around here. I used to be a tech, now I teach automotive...so I'm very much out of the loop in terms of everyday industry trends. I try to stay up to date but it's hard.   

Edited by Doublebase
  • Like 2
Link to comment
Share on other sites

My boss has a 16 GMC with the 6 speed he had the trans replaced at 80k all highway miles. It lost 3rd gear I have the 8 speed I feel there solid but shift worse then the 6 speeds.


Sent from my iPhone using Tapatalk

Link to comment
Share on other sites

On 2/9/2020 at 9:10 AM, silveradosid said:

so is the assumption that no matter how many times you change the fluid the torque converter is still going to fail

Basically. Fluid change is still helpful of course, but this is beyond a fluid issue.

Link to comment
Share on other sites

Simple.

Fluid changes extend it's life IMO.

All this talk of failures.

It's the luck of the draw if you get one with a problem.

My 6 speed has been smooth since bought used with 41 K miles.

Now over 70 K miles.

:)

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.




×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.