TH400 Pump 1964, remanufactured and ready to install. Fits the TH400. Ships fast from the USA.
The 1964 model year is where the Turbo Hydra-Matic 400 started, in Cadillac and Buick cars, a year before Chevrolet and Oldsmobile picked it up. If you are restoring one of those first-year cars and the transmission whines with engine speed, picks up Drive slowly once it is warm, or slips in every gear, the front pump is the first part to suspect. This is a remanufactured TH400 pump listed for 1964 units, shown with the pump body, the cover with its stator shaft, the pump-to-case gasket and new sealing rings.
The TH400 uses an internal gear pump bolted to the front of the case. The converter hub rides in the pump bushing, and two tangs on the hub turn the drive gear at engine speed inside the driven gear, with a crescent separating the suction and pressure sides. The cast-iron cover carries the stator shaft, the pressure regulator valve and the boost valve, and its sealing rings feed oil to the forward clutch. Everything downstream depends on it: line pressure to every clutch and band, converter charge, cooler flow and the lube circuit that keeps the gear train alive. When gear and pocket clearances open up or the regulator bore wears, pressure drops or goes uncontrolled, and the whole transmission suffers at once.
Rule out low fluid, a plugged filter and a rolled filter O-ring first, since each can sound exactly like a bad pump. Then put a gauge on the line pressure tap: GM's figure for Park, Neutral and Drive is roughly 60 to 90 psi at 1000 rpm with the modulator connected. Test cold and again at full temperature; a pump that makes spec cold and falls well short hot is worn. Our TH400 pump failure guide has the full pressure chart and inspection points, and the TH400 common problems guide covers the non-pump causes.
This pump is listed for the 1964 TH400 only. First-year units came from the Cadillac and Buick lines, and some early Buick, Olds and Cadillac TH400s used a variable pitch (switch-pitch) stator converter, identified by a two-prong plug on the case and a narrower stator spline at the pump. A switch-pitch converter and a fixed-stator pump are not a matched set, so check your case for the two-prong plug, compare the stator spline and bolt pattern on your old pump, and keep the original converter type. If you are unsure, send us the year, vehicle and VIN or the ID plate code before ordering. For 1965-1967 units see the TH400 pump for 1964-1967, and all early parts are on the TH400 parts page.
If the clutches are burnt from running on low pressure, rebuild the unit at the same time with the TH400 master rebuild kit for 1964, and center the pump with a front pump alignment band tool. The TH400 rebuild wear points guide covers the endplay checks to make while the pump is out.
| Fits | TH400 1964 |
| 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.
It is listed for 1964 units. Early and late TH400 pumps differ in details such as the stator shaft for switch-pitch converters, so match your old pump or send us your year and VIN. Later units have their own listings on the TH400 parts page.
Look for a two-prong electrical plug on the side of the case, used on 1965-1967 Buick, Olds and Cadillac variable pitch units. With the converter out, the stator spline at the pump is also narrower on switch-pitch transmissions.
A new front seal and pump-to-case O-ring at minimum. If the fluid is burnt or the clutches slipped on low pressure, rebuild the unit with a master kit while it is out.
Yes. Reverse needs the highest line pressure, so a worn pump often shows up first as slow or slipping Reverse when the fluid is hot. Confirm with a pressure gauge before pulling the transmission.
Use a current licensed DEXRON automatic transmission fluid, and prime the new pump with fluid before the first start so it does not run dry.
