Thanks to those who responded to my overdrive question. The problem of
violent hitching on deceleration with or without overdrive has been
resolved. A day or so after posting the question when spirited shifting into
third gear, the overdrive engaged even though the switch was off! Let off
and it would drop out of OD. A short while back I had issues with a plugged
relief valve that created all sorts of strange problems.
With the relief valve plugged, pressure spiked to 900 psi with the OD
engaged and only dropped to 300 psi when disengaged. That 300 psi was enough
pressure to partially engage the OD at highway speeds and gave a driveline
vibration sensation as if a u-joint was bad or a wheel hub was about to fall
off. Although the symptoms were a bit different, a partially plugged relief
valve was again the culprit. Evidently it kept pressures up all the time and
when decelerating it would violently hitch and nearly lock up the rear
wheels. Maybe someone can explain the why's of this to me? This time only
one side of the relief was plugged and once cleaned, performed again
perfectly. I have ordered a new filter from the local Volvo dealer to
replace the one falling apart and letting fly with bits of potting that plug
the relief valve. The transmission fluid is very clear now so all the loose
bits may finally be out of circulation.
It was a beautiful Maine evening and a wonderful chance for a long test ride
on the winding back roads. Life is good again.
Happy 4th of July to all,
Rick Patton
Brunswick Maine
http://topshamautoparts.com/tr6/
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