5R55W Pump, remanufactured and ready to install. Fits the 5R55W. Ships fast from the USA.
A 2002 or 2003 Explorer or Mountaineer with a 5R55W that hesitates before it goes into Drive or Reverse, whines with engine speed, or slips everywhere once the fluid is hot is a candidate for a new front pump. This is a remanufactured 5R55W pump, built and ready to install, so you are not reusing a body, gear set and bushing with 150,000 miles of wear on them. It carries a 1-year warranty.
Everything in the 5R55W runs on oil from this pump. It sits behind the converter and is driven by the converter hub; its output feeds the main regulator in the valve body, and from there the shift solenoids and the PCA, PCB and PCC pressure control solenoids decide where the pressure goes. Two pieces of the pump wear in ways that are well known on this unit: the flow control valve, which bleeds surplus pressure back to the suction side and can stick open, and the finish-in-place bushing in the pump cover that supports the converter hub. Either one lets pressure or fluid escape before it ever reaches a clutch.
A 5R55W delay is not automatically a pump. The same complaint comes from a worn servo pin bore, valve body bores or a weak solenoid pack, and a GEARS case study on a 2006 Explorer found a damaged forward clutch behind a severe warm delay with normal electrical readings. Start with a correct fluid level at the check plug, then a line pressure test. Low pressure in every range points at the pump; normal pressure with a delay points downstream. Our 5R55W pump failure symptoms guide separates the flow control valve, bushing and regulator failures, and the 5R55 harsh and delayed shift walkthrough covers the servo and valve body causes.
This pump is for the 5R55W. Sonnax places the W in the 2002-2003 Ford Explorer and Mercury Mountaineer; for 2004-2005 those trucks moved to the 5R55S, which has a 38-tooth overdrive sun gear where the W has 24. The two look almost the same on the outside, so read the transmission code on the driver's door label rather than going by model year, and compare your old pump to this one or send us the year and VIN. If you are not sure what you have, the 5R55 identification guide walks through it. Every other part for this platform is in our 5R55 parts collection.
The transmission comes out for this job. Inspect the converter hub before reusing the converter, because a grooved hub will wear the new bushing and seal. Install a new front seal and O-ring, tighten the pump bolts evenly in a cross pattern, and check input shaft end play. If the old pump was scored by debris, that debris came from somewhere; a 5R55W valve body is worth considering if the bores were contaminated, and the solenoid block pack if a pressure control code was stored. Flush the cooler lines, fill with Mercon V, and set the level at the T30 torx check plug in the pan with the engine running and the fluid at temperature - behind the 4.0 and 4.6 liter Explorer engines a dry fill is roughly 12.4 to 12.7 quarts. Clear codes and drive it through several full shift cycles so the PCM relearns.
| Fits | 5R55W |
| Part type | Pump |
| Condition | Remanufactured |
| Brand | OEM |
| Ships | From the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
The 2002-2003 Ford Explorer and Mercury Mountaineer five-speed automatics. The 2004-2005 trucks use the 5R55S. Check the transmission code on the door label, or send us your VIN, to be sure.
Run a line pressure test. Low pressure in every range points to the pump; normal pressure with a delayed or slipping apply points to the valve body, a worn servo pin bore or the clutch itself.
A front seal and pump O-ring, a filter and pan gasket, and a cooler line flush. Inspect the converter hub too. If debris damaged the pump, plan on rebuilding the rest of the unit.
Mercon V ATF. There is no dipstick. The level is set at the T30 torx check plug in the pan with the engine running and the fluid hot. A dry fill behind the 4.0 or 4.6 liter is about 12.4 to 12.7 quarts.
It can. The converter hub rides in a bushing in the pump cover, and Sonnax links worn bushing clearance to repeat front seal leaks and converter hub wear. A new pump includes a fresh bushing.
