Descrizione
Two part numbers, one digit apart, and a steady stream of wrong orders. This page exists partly to sell a pump and partly to stop that mistake happening on your machine.
What Caterpillar lists
247-8968 appears in the Caterpillar catalogue as PUMP GP-PS-B, described as an axial piston pump with variable displacement, and it is carried in Cat’s remanufactured parts programme. The alternate reference is 10R-6278. Fitment in parts data covers CAT 365B, 365B II, 365C, 365C L, 365C L MH and 374D L.
247-8968 is not 247-8978
The other number in that pair, 247-8978, is listed by Caterpillar as a slipper piston motor, cross-referenced as 10R-6276, and it is the fan motor on 385C and 390D machines with the C18 engine. One is the supply side of the circuit, the other is the working side. They share nothing except a prefix, and a workshop that orders from a half-remembered number will end up holding the wrong unit while the machine sits.
| Number | Cat item name | Role | Where it is fitted |
|---|---|---|---|
| 247-8968 / 10R-6278 | PUMP GP-PS-B, variable displacement axial piston | Fan pump, supplies and meters oil | 365B, 365C, 365C L, 374D L |
| 247-8978 / 10R-6276 | Slipper piston motor | Fan motor, drives the fan | 385C, 390D, C18 engines |
| 225-4613 / 10R-6268 | Motor GP-PSF, fixed displacement | Fan motor | 365C, 365C L, C15 engines |
What a variable displacement fan pump does
Caterpillar’s specification for the 365C states that the side-by-side cooling system allows operation in ambient temperatures up to 52 C, and that the Electric Power Control varies fan speed according to coolant temperature and hydraulic oil temperature. The pump on this page is the actuator of that instruction. It receives a control signal and changes how much oil it sends to the motor.
That gives three distinct failures rather than one. The pump can lose volumetric efficiency through internal wear, in which case it never reaches full flow. Its control can stick, in which case it may sit at part displacement regardless of demand and look exactly like a failed motor. Or the machine can simply stop asking for cooling, because a sensor or a wiring fault holds the command low. Work through the command and the delivery before condemning the unit. Our fan pump diagnosis guide e regulator diagnosis and adjustment article cover both tests, and the motor side is in the fan motor diagnosis guide.
Fitting a replacement
- Lay the old pump next to the new one before removing anything from the machine. Check shaft spline count and length, pilot diameter, mounting bolt pattern, port thread sizes and the side the control sits on.
- Drain into a clean container and inspect. Varnish or glitter tells you whether a flush is needed as well as a replacement.
- Fit a new return filter element and clear the suction strainer. Target cleanliness around ISO 4406 18/16/13, the class Bosch Rexroth guidance gives for axial piston units in mobile service.
- Prime the casing and the suction line with clean oil. Never crank an axial piston pump dry.
- Run the case drain straight to tank, unrestricted, and confirm the hose has not been pinched behind a bracket during refitting.
- Check the control connector and its wiring before starting.
- Prove the result under thermal load and log coolant and hydraulic oil temperature at low and high idle.
Pairing and terms
If your 365C needs the motor rather than the pump, it is 225-4613, listed on our 225-4613 fan motor page. Minimum order one piece on this pump, three to six month warranty on new aftermarket units as stated on the proforma invoice, wooden case packing, delivery 5 to 8 working days from payment subject to stock, and inspection photographs before the case closes. Send the plate number and machine serial prefix and we will confirm the fitment before invoicing. The rest of the CAT cooling drive range is under Caterpillar hydraulic fan motor.
