A/T - 700R4, 2004R No Line Pressure Rise
TECHNICAL BULLETIN # 201DATE: December 93
TRANSMISSION: 700-R4, 200-4R
SUBJECT: No Line Pressure Rise
APPLICATION: GM
700-R4 / 200-4R
No Line Pressure Rise
A complaint of no line rise may be caused by a stuck pump slide. Obviously, a slide that is too thick for the depth of the pump pocket could be the cause. To check For this condition place only the slide (steel ring & 0-ring removed) in the pump pocket. Lay a suit-able straight-edge across the pump face, and using a feeler gauge between the slide and straight-edge, measure the clearance. Acceptable clearance is .0015 - .0025, but .002 is generally preferred (Figure 1).
Rebuilt or reconditioned pumps may present another problem resulting from the type of machining done during the reconditioning process.
Pay particular attention to the corner area of the pump pocket. The pump pocket must be machined with either a 90° angle or an undercut in the bottom corner (Figure 2). A radius in the bottom corner of the pump pocket may allow the slide to stick when the edge of the slide contacts the radius.