4L80E Pump 1997-03, remanufactured and ready to install. Fits the 4L80E. Ships fast from the USA.
When a 1997-2003 Silverado or Sierra 2500/3500, Suburban 2500 or Express van with a 4L80E is slow to go into gear when hot, slips everywhere, whines with engine speed or buzzes with wild line pressure in Reverse, the problem is often in the front pump. This is a remanufactured 4L80E pump for that 1997-2003 window, so you bolt in a complete, built assembly instead of rebuilding a worn cover and gear set on the bench.
The pump is driven by the converter hub and turns whenever the engine runs. Its gears make the flow, and the valves in its cover decide what that flow becomes: the pressure regulator valve sets line pressure and feeds the converter and cooler, and the boost valve raises pressure when the computer or Reverse calls for it. Every clutch, band and the converter depend on those two valves. From 1997 the cooler return no longer comes back through the pump; GM moved it to the center support for center-gearbox lubrication, and pumps for this generation are built for that layout. That is one reason a 1991-1996 pump is a different part.
Put a gauge on the line pressure port and compare idle and stall readings in each range against the factory chart. Low pressure in every range points at the pump or a leak downstream; high or uncontrolled pressure points at the boost valve and regulator in the pump cover or at the EPC circuit. Rule out the solenoid first with our 4L80E EPC solenoid symptoms guide, and use the 4L80E heavy-duty transmission guide for the rest of the pressure-side checks. Metal in the pan or a scored converter hub means the pump is only part of the job.
This pump is listed for 1997-2003 4L80E applications. 2004-up trucks use a later pump, see the 2004 4L80E pump, and 1991-1996 units take the earlier design. Transmissions are often swapped between trucks, so match the pump body and stator shaft to your old one or send us the transmission year and VIN and we will confirm before it ships. Every part we stock for this unit is on the 4L80E collection page.
| Fits | 4L80E 1997-03 |
| Part type | Pump |
| Condition | Remanufactured |
| Brand | Sonnax |
| Ships | From the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
No. It is listed for 1997-2003 units. 2004 and later trucks use a later pump, which we list separately.
Yes. Sonnax documents that a worn boost valve sleeve in the 4L80E pump lets reverse oil leak into the torque signal circuit, causing line rise as high as 500-600 psi and a buzz, which can break direct clutch drums and pistons.
Yes. Install a new front seal and inspect the converter hub for grooves. A rough hub will chew up a new seal and bushing.
On 1999-later 4L80E trucks, Sonnax notes the factory EPC pressure was set high at idle, which combined with the stock pressure regulator valve can cause idle surge and low cooler flow.
Dexron VI. It is GM's current fluid and is backward compatible with the Dexron III these trucks originally used.
