A/T - 700R4 Low Mainline Oil Pressure

TSB 86-28 (June)

700 R4

SUBJECT: Low Mainline Oil Pressure

COMPLAINT:

Low mainline oil pressure at idle, especially after metal contamination of the transmission.

SOLUTION:





Examine the pressure relief check ball and spring (see figure) This check ball controls excessive mainline oil pressure. If the transmission has extremely high pressure due to a stuck, or wrong pressure regulation valve, the pressure relief ball should prevent mainline oil pressure from exceeding approximately 400 P.S.I. If this ball is stuck off its seat, or has foreign material preventing its proper seating, mainline pressure will exhaust into the sump