6L90 third gear shift flare solved CTS-V (air from sitting)

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Aug 26, 2009
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I've had an ongoing issue with my second gen CTS-V where I get a flare on the shift to third. Could never solve or make sense of it except that I knew it began after a long period of sitting (over a year). It did seem to go away sometimes but without fail would return. I never drove the car consistently and this issue just had me leaving it alone ever more.

I stumbled upon a comment on a different forum that the 6L90 gets an air pocket or air somewhere after sitting for long periods that causes this and the fix is to leave it in reverse for a long length of time.

Boom problem solved. I always back it in to when it gets stored so everytime it's come out it goes into drive and is on its way with no reverse. This time I pulled it out and drove around a little, got the flare on every 3rd gear shift no matter which drive mode...put it in reverse and sat there for a few minutes...back in drive and it was gone. Drove it for a week with zero issues for the first time in a long time.


 
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On the C7 there is a procedure for purging the air from the system after fluid swaps. I wonder if similar exists for these.
 
I've had an ongoing issue with my second gen CTS-V where I get a flare on the shift to third. Could never solve or make sense of it except that I knew it began after a long period of sitting (over a year). It did seem to go away sometimes but without fail would return. I never drove the car consistently and this issue just had me leaving it alone ever more.

I stumbled upon a comment on a different forum that the 6L90 gets an air pocket or air somewhere after sitting for long periods that causes this and the fix is to leave it in reverse for a long length of time.

Boom problem solved. I always back it in to when it gets stored so everytime it's come out it goes into drive and is on its way with no reverse. This time I pulled it out and drove around a little, got the flare on every 3rd gear shift no matter which drive mode...put it in reverse and sat there for a few minutes...back in drive and it was gone. Drove it for a week with zero issues for the first time in a long time.



Wow! That car sounds really good! Quick too.
 
I have the 6L90 in my Sierra, and it will flare every time I start the engine and drive forward without reversing first. Been doing this ever since I bought it with 18k miles on it. (127k now) Doesn't matter if the engine was off 30 seconds or 30 days. I just do my best to park where I need to reverse first. The TSB I saw years ago mentioned the air pocket, and said no adverse effects from this behavior. So far so good in my case.
 
I have the 6L90 in my Sierra, and it will flare every time I start the engine and drive forward without reversing first. Been doing this ever since I bought it with 18k miles on it. (127k now) Doesn't matter if the engine was off 30 seconds or 30 days. I just do my best to park where I need to reverse first. The TSB I saw years ago mentioned the air pocket, and said no adverse effects from this behavior. So far so good in my case.

Interesting. Wonder how many early trade ins happened over something like this.
 
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