Complete front pump assembly for the ZF 4HP16 four-speed automatic, for low line pressure, slow engagement and slipping in Optra and Forenza cars.
If your Suzuki Forenza, Suzuki Reno, Chevrolet Optra or Epica takes a long breath before it drops into Drive or Reverse, slips once it is warm, or whines in step with the engine, the front pump in its ZF 4HP16 is one of the first places to look. This is a complete 4HP16 front oil pump assembly, reference number 189500, sold as a finished unit so you are not piecing together a body, cover and gears from separate sources.
The 4HP16 is a four-speed front-wheel-drive automatic that ZF developed with Daewoo around 2000, after which Daewoo took over production and support. GM and Suzuki then used it in the Forenza, Reno, Verona, Optra, Epica and several Daewoo and Buick models. It has five friction elements, two rotating clutches and three stationary brakes, and no one-way clutches or bands. That means every shift is a clutch-to-clutch handoff controlled by the valve body and its six solenoids, and every one of those handoffs depends on steady line pressure from this pump.
The pump itself is a gear-type unit driven directly by the torque converter hub at the bellhousing end of the case. Two details set it apart from most pumps: the cover is nearly flat because there is no sealing-ring tower, and the seal and bushing bore is offset from the pump outside diameter, with a spacer washer under the front seal. Directly behind it sits the output-gear support, which also houses the F-clutch piston.
Check the fluid level and condition first, because a low or burnt fill causes the same delay and slip. Our ATF color and smell chart helps you read what comes out. If the fluid is right, put a gauge on the line pressure tap and compare idle and stall readings; low pressure in every range points at the pump or the regulator side rather than one clutch. The line pressure testing guide walks through the hookup. A pump whine that changes with RPM in Park and Neutral is another strong pointer, and a worn hub on the converter tells you to look at the bushing too; see converter hub and pump bushing wear.
This assembly is for the ZF 4HP16 four-speed only. Known 4HP16 applications include the Suzuki Forenza, Reno and Verona, the Chevrolet Optra, Epica and Orlando, the Buick Excelle, and the Daewoo Lacetti, Leganza, Magnus and Rezzo. The listing does not break fitment down by model year, so confirm your unit is a 4HP16 by the tag on the case, and compare the old pump with this one before installing: stator splines, bolt pattern and the seal ring lands. Similar-looking compact cars from other brands use Aisin or Hyundai four-speeds that this pump will not fit. If you are not sure, send us your year and VIN before ordering. Browse other internal parts in our hard parts category.
| Transmission | ZF 4HP16 four-speed automatic |
| Part number | 189500 |
| Type | Complete front oil pump assembly |
| Material | Steel |
| Weight | 8.3 lb |
It fits Forenza models with the ZF 4HP16 automatic, which is the four-speed automatic used in that car. Check the tag on the transmission case and compare the old pump splines and bolt pattern before installing, or send us your year and VIN.
The Suzuki Forenza owner manual lists ESSO LT 71141 or TOTAL ATF H50235 for the automatic transaxle. Some generic charts list Dexron, but follow the owner manual for your car.
A worn pump drops pressure in every range, so engagement is slow into both Drive and Reverse and slipping shows up in all gears when hot. A single failed clutch usually affects only the gears that use it. A line pressure gauge reading low across the board confirms the pump side.
Replace the front seal and outer O-ring, check the converter hub and bushing for wear, and flush the cooler and lines if the old pump was damaged by clutch debris. A scored converter hub should be addressed so it does not wear the new parts.
No. It uses two rotating clutches and three stationary brakes with no bands or one-way clutches, so every shift is clutch-to-clutch. That is why low pump pressure shows up quickly as flares and slips.
