I’m glad Dennis answered as the original question didn’t come to my inbox or junk mail. 

And, I follow AT transmission discussions!

Eric Caron 

> On Mar 25, 2020, at 6:08 PM, Dennis Haynes <d23haynes57@HOTMAIL.COM> wrote:
> 
> From a design perspective  I find it amazing that this simple automatic transmission works as well as it does regardless of fluid temperature and related viscosity.  Since it works well cold this is not an adjustment issue. As shift points and the inner working rely on pressure what is most likely happening is that you have an internal leak or the pump is worn-damaged and once the fluid is warm you don't have sufficient pressure for the valve body to do what is needed or you can't lock up the direct clutch. 
> 
> You can do some diagnosing with a pressure gauge. The Bentley has the details. You can also drop the valve body and using an air gun with rubber tip operate each of the clutches and 2nd gear brake band.  Were you the person that had the shafts come out with the torque converter? Could be the seal rings on the turbine shaft are broken. 
> 
> Drop the pan and check that the filter is clear. A restricted filter can also cuase shift propblems. If it is clogged enough to be a problem an overhaul is inevitable anyway. 
> 
> Dennis
> 
> 
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Bill Marshall
> Sent: Wednesday, March 25, 2020 12:42 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Auto trans not upshifting
> 
> Hi folks, my AT is acting up.  It shifts fine when cold, but when warm will not upshift to 3rd at all.  I recently removed and installed it, but did nothing to it as far as adjustments go.
> Could it be the shifter cable shifted?  Kickdown too tight/loose?  Any ideas would be appreciated.  Thaknks.
> 
> Bill Marshall
> 88 GL auto