As the valve bore wears at the inboard spool, line pressure escalates with increased temperature and the pressure regulator valve does not stroke, reducing converter charge. As line pressure goes up, servo covers and pistons have excess pressure in reverse. Delayed engagements occur as the converter feed is reduced with excess bore wear. Line pressure will be reduced as the circuits between line, converter and exhaust wear. The Sonnax pressure regulator valve kit 56947J-39K can restore proper hydraulic function and prevent future wear.
Wear is visible or if vacuum test results in leakage as indicated:
A. Balanceline pressure port
B. Line pressure port
C. Converter charge pressure port