Açıklama
The title of this page used to describe 266-8034 as a fan pump. That was incorrect and it has been fixed. Caterpillar’s own catalogue entry for 266-8034 is a hydraulic fan slipper piston motor, and the parts book item name in the same family is a piston motor group. Anyone who landed here looking for a pump was being sent to the wrong component, so the correction is stated plainly at the top rather than buried.
What the part is
A slipper piston motor, fixed displacement, sitting behind the fan on a 345C and converting the flow from the fan pump into shaft speed. It has no regulator of its own, which is why a motor this simple can be blamed for faults that originate upstream in the pump, its control, or the machine’s temperature sensors.
The 345C machine context
The 345C is a machine of approximately 44,970 kg operating weight, powered by a Caterpillar C13 producing 239 kW (321 hp) net. Caterpillar’s own literature for the 345D that followed states that it delivers 18 percent more horsepower than the 345C, which places the 345C in the 239 to 240 kW band and confirms the figure rather than relying on aftermarket data pages that list it variously at 257 kW and 345 hp.
Which part you actually need
| Belirti | Most likely component | Test that settles it |
|---|---|---|
| Fan slow at every engine speed, oil temperature climbing first | Fan motor internal wear | Drain flow test at the motor with the fan commanded to full |
| Fan slow, coolant normal, no drain anomaly | Fan pump or its control | Flow and pressure measurement at pump output |
| Fan never reaches full speed, monitor shows no fault | Temperature sensor or wiring | Resistance and signal check on the coolant sensor |
| Fan speed normal, machine still hot | Radiator core, not hydraulics | Airflow check with the core cleaned |
| Noise from the pump train with heat | Cavitation or drive train wear | Suction line, strainer and transfer case inspection |
The written procedures for each of these are in our hidrolik fan motoru teşhis kılavuzumuzla başlayın ve fan pompası teşhis kılavuzumuz, and the sensor check is in coolant temperature sensor testing.
Two warnings about this part number in the aftermarket
First, the pump confusion. Listings for 266-8034 appear under both fan pump and fan motor headings, sometimes in the same title with hydraulic gear pump added as well. That is keyword matching, not parts knowledge. The number is a motor.
Second, the dozer claim. Some catalogues attach 266-8034 to CAT D8R machines. We have not been able to verify that fitment against any Caterpillar source, and we do not sell it on that basis. If you have a D8R with a failed fan motor, send the number cast on your unit and the machine serial prefix and we will identify the correct part rather than guessing from a model name.
Fitting and aftercare
Flush the circuit if the removed motor produced debris, and fit a new return filter element as part of the job. Fill the casing with clean oil before the first crank. Keep the case drain unrestricted to tank, since back-pressure in the housing is what finishes shaft seals. Confirm rotation with the fan restrained before the guard goes back. Target cleanliness around ISO 4406 18/16/13, the class Bosch Rexroth guidance gives for axial and slipper piston units in mobile service.
Terms
Minimum order one piece. Replacement units carry a three to six month warranty as stated on your proforma invoice; genuine and used stock is sold without warranty. Bench tested, photographed against your order before packing, wooden case, delivery 5 to 8 working days from payment subject to stock, by sea, air or express courier. The 345B motor for the previous generation is 155-9107, listed on its own page, and the full CAT range is under Caterpillar hydraulic fan motor.
