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There is a useful lesson hiding in this part number. The same fan motor is listed for a 345B with a 3176C engine and for a 330D with a C9, two machines roughly a decade apart. That tells you something about how Caterpillar buys hydraulic components, and it tells you why model-based searching fails on parts like this one.
What the part is
155-9107 is catalogued by Caterpillar as a fixed displacement motor, with the parts book item name MOTOR GP-PISTON. The alternate reference 0R-7795 is the same position under a different catalogue number, and in the trade these motors are also sold against the manufacturer’s own numbering, since Cat sourced this family of fan motors from a component maker rather than building it in house. If you are chasing a seal kit rather than a whole unit, the underlying manufacturer number is the one that helps.
Fitment, and the reason it spans two generations
Listed for CAT 345B, 345B L, 345B Series II, 345B L Series II, 345B II, 345B II MH, 345B LC and the W345B II wheel loader material handler, with the 3176 and 3176C ATAAC engines. It is also listed for 330D, 330D L and 330D LN with the C9.
That overlap is not a catalogue error. A fan motor is a bolt-on hydraulic component with a limited set of sizes, and a manufacturer that changes an excavator engine from a 3176C to a C9 has no reason to re-tool a cooling fan motor that already fits the space, the shaft and the port pattern. What does change between those machines is the pump that feeds the motor and the control logic that commands it. So when you order, the model badge is the weakest piece of evidence you have. The number on the old housing is the strongest.
The 345B machine context
Caterpillar’s specification for the 345B L Series II gives an operating weight of 44,460 kg in that configuration, net flywheel power of 239 kW (321 hp) to ISO 9249 and SAE J1349 from a 3176C ATAAC engine, main system maximum flow of 360 L/min with a 41 L/min pilot circuit, and a cooling system capacity of 45 litre.
Be careful with figures quoted for a plain 345B. Earlier 345B builds are published at around 43,000 kg with a gross rating of 290 hp, and some aftermarket data pages give 223 kW for a 345B L, which matches neither. The Series II distinction and the serial prefix are what make the numbers mean something, and none of them change which fan motor you need.
Diagnosing before you replace
The B-series cooling package is simpler than the D-series that followed it, so the test list is shorter:
- Confirm the complaint with a thermometer reading, not a gauge glance. Coolant and hydraulic oil temperature at low idle and high idle, under load.
- Check the core from outside before anything is stripped. A 345B working in clay or demolition dust will plug a radiator face in a season, and airflow loss from a blocked core looks identical to a worn motor.
- Spin the motor with the fan removed. Roughness through the rotation, or grit in the case drain, is your answer.
- Measure the supply. If flow at the motor ports is short of specification, the fault is upstream on the pump, and our fan pump diagnosis guide covers that side.
- Only then replace the motor, and change the return filter element as part of the job.
The motor-side test sequence is set out in our hydraulic fan motor diagnosis guide.
One caution about this number in the aftermarket
155-9107 appears in supplier listings attached to a wide range of machines, some of which take a different motor entirely, and the same listings often mix it with 266-8034, which is the 345C fan motor rather than a pump as some pages claim. Numbers in this family get reused across listings because sellers are keyword-matching, not reading parts books. Send us the plate from your unit and we will confirm against it rather than against a search term.
Terms
Minimum order one piece. New aftermarket units carry a three to six month warranty as stated on your proforma invoice; genuine and used stock is sold without warranty. Bench checked, photographed against your order before the wooden case closes, delivery 5 to 8 working days from payment subject to stock, by sea, air, or DHL, FedEx, TNT and EMS. The 345C motor is on our 266-8034 page, and the rest of the CAT cooling drive range is under Caterpillar hydraulic fan motor.
