ZF 4HP16 Automatic Transmission Front Oil Pump Assembly

This is a complete front oil pump assembly for the ZF 4HP16, the four-speed transverse automatic GM Daewoo put behind the 1.8L and 2.0L four-cylinders in cars like the Chevrolet Optra and the Suzuki Forenza and Reno. It comes as a finished assembly, so you are not chasing a separate body, cover and gear set. The reference number on it is 189500.

On the 4HP16 the pump is the only source of line pressure. When the gears or the pocket wear, or the body gets scored from debris after a clutch failure, pressure drops off at idle and when the fluid is hot. The symptoms are the ones these cars are known for: a long pause going into Drive or Reverse, flare on the 2-3 shift, slipping once it warms up, and a whine that follows engine speed rather than road speed.

On the bench, pull the converter, remove the pump bolts and use slide hammers in the threaded holes to draw the old pump out of the case. Compare the new unit to the old one before it goes in: stator splines, bolt pattern and the seal ring lands on the stator support. Lube the new outer O-ring and front seal with ATF, draw the pump in evenly with the bolts in a cross pattern, and check that the input shaft still turns by hand before the converter goes back on. If the old pump failed from clutch debris, flush the cooler and lines before the car goes back out.

Confirm your transmission is a ZF 4HP16 by the tag on the case before ordering. This fits the 4HP16 only, not the Aisin or Hyundai four-speeds used in similar cars.