TH400 Pump, remanufactured and ready to install. Fits the TH400. Ships fast from the USA.
For most Turbo 400s on the road and at the track, the pump that needs replacing is the common fixed-stator 6-bolt design. This is a complete remanufactured TH400 pump assembly, part number ER34500, rebuilt to OEM spec with new pump gears, a new pump body bushing, new front and rear stator bushings, a new front seal, new sealing rings, a new O-ring, gasket and thrust washer. If your truck, motorhome or muscle car groans in every gear, engages late after a long drive, or burns through clutches, it is ready to bolt in and get pressure back.
The TH400 pump is a crescent gear pump driven by two tangs on the converter hub. It is the only thing making pressure in the transmission. Oil leaves the pump through the pressure regulator to apply every clutch and band, charges the converter, and flows out to the cooler; the return comes back through the stator shaft to lubricate the geartrain. GEARS Magazine puts converter charge at about 60 psi under load and maximum line pressure near 180 psi on the 400. Three wear points end most pumps: the babbit body bushing wears and lets the hub run off center, the gears scuff the pocket and crescent, and the pressure regulator bore wears oval on high-mileage units.
Gauge the line pressure before you pull the transmission. GM specifies about 60 to 90 psi in Drive at 1000 rpm with the vacuum modulator connected, and it should rise smoothly under load. A pump that tests fine cold and falls off hot is worn. Check the modulator for fluid in its vacuum line too, since a leaking one gives low pressure and burnt fluid. The TH400 pump failure guide has the full chart, and TH400 common problems and fixes covers the modulator and clutch failures that sit beside pump wear.
This assembly is the 6-bolt, fixed-stator TH400 pump. The listing does not tie it to a year range, so match it to your old pump before ordering: count the bolts, compare the stator spline and check the face for the same layout. It does not fit switch-pitch transmissions or the early 8-bolt pumps. Those have their own listings, the 1965-1967 switch-pitch pump and the 1964-67 first-design pump. If you are not sure which you have, send us a photo of the pump face with the year and VIN. Everything else for the 400 is on the TH400 parts page.
A failed pump usually means a rebuild is due. The TH400 overhaul kit covers the gaskets and seals, and a Trans-Scat valve body shift kit firms up shifts while the pan is off.
| Fits | TH400 |
| Part type | Pump |
| Condition | Remanufactured |
| Brand | GM |
| Ships | From the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
It is the common fixed-stator 6-bolt pump. It does not fit switch-pitch transmissions or early 8-bolt pumps. Compare bolt count and stator spline with your old pump, or send us a photo and your VIN.
New pump gears, pump body bushing, front and rear stator bushings, front seal, sealing rings, O-ring, gasket and washer, rebuilt to OEM specification.
Yes. Check that the body and cover are centered and torque the bolts evenly before installing it, then confirm the input shaft turns freely.
Yes. A leaking vacuum modulator lowers line pressure and burns fluid. Pull the vacuum line and check for fluid before blaming the pump.
If the gears are scored, the bushing is worn or the regulator bore is oval, yes. A complete reman pump saves the machine work of rebuilding the old one.
