Date:         Sun, 27 Jul 2003 17:28:57 -0400
Reply-To:     Edward Maglott <emaglott@BUNCOMBE.MAIN.NC.US>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Edward Maglott <emaglott@BUNCOMBE.MAIN.NC.US>
Subject:      interpreting Automatic transmission pressures
Content-Type: text/plain; charset="us-ascii"; format=flowed

I'm trying to troubleshoot my just-rebuilt automatic transmission.  I
rebuilt it myself.  Here are the symptoms and what I have done:
1st round:
Got my AT back in, and fluid finally filled up to the correct level.  It
moves off from idle quite nicely in both forward and reverse.  However, it
will not shift to 2nd.  at high speeds if I lift off the gas, it freewheels
unless I put it in "1".
2nd round:
I was suspicious of the 2nd gear brake band adjustment.  I adjusted it with
the trans out of the vehicle, per Bentley.  The torque wrench I was using
only went down to 5nm, which is the final adjustment point.  I know those
wrenches are not too accurate at the ends of their ranges.  So I decided to
re-check that adjustment.  I loosened the locknut, and the adjusting screw
was very loose.  I could turn it probably 2 turns with my fingers.  So I
experimented with various settings.  I found a "too tight" setting where
the trans was binding in reverse.  I backed off from there until there was
no binding.  At this setting, I had the same symptoms as before, but got
sort of a mushy attempt to go into second when the rpms got pretty
high.  Any pressure on the gas pedal would throw it back to first or a sort
of "neutral-revving-engine" gear.
3rd round:
2 days later, I swapped in a different governor.  It is also from an NK
code trans, and has the same "A" stamped on it.  Tried again, and now it
would go all the way into second and hold even with pressure on the
gas.  But no third.
4th round:
Today I checked the transmission main pressures per Bentley.  In Drive at
idle, spec is 41-43, I got 50.  In drive at full throttle, spec is 96-98, I
got 112.  In reverse at idle, spec is 128-142, I got 100.  Hmmm, the only
symptom I have with reverse is that sometimes it is a little slow to
engage, and seems to happen in 2 actions.  Like "ka-thnk", instead of just
"thnk".  Other than the reverse pressure being a little low, the main
pressure seems to be high.  Also, at idle, in park, the pressure when cold
was hanging around 135, If I blipped the throttle quickly, it would shoot
up to 225 or more for an instant.  And this was not a blip that raised the
rpms much at all.  So that pressure spike was a result of the action of the
throttle pressure valve.  Once it was warmed up both the "park" idle
pressure and the "blip" pressure dropped slightly.  Any ideas on where to
proceed to next in my quest?
Edward