Description
Caterpillar’s own description of the 345D cooling system is the clearest statement of what this motor is being asked to do, so it is worth quoting in full rather than paraphrasing.
The 345D layout completely separates the cooling system from the engine compartment. The cooling fan is hydraulically driven with variable speed control based on the ambient temperature, coolant temperature, and hydraulic oil temperature. This unique feature assists in the management of engine power and improves noise efficiency while providing optimized cooling.
Three sensor inputs, one proportional command, and a fixed displacement motor at the end of it. The motor’s job is not to modulate anything. Its job is to convert whatever flow it is given into shaft speed, cleanly, for thousands of hours. When it cannot, you lose airflow exactly when the machine most needs it, and the energy that should have moved air ends up as heat in the hydraulic oil.
Machine data for the 345D
| Article | Published figure, Caterpillar specification |
|---|---|
| Operating weight, 345D | 44,970 kg (99,150 lb) |
| Operating weight, 345D L | 45,375 kg (100,040 lb), up to 49,265 kg in variable long undercarriage |
| Moteur | Caterpillar C13 ACERT, 12.5 litre, 130 x 157 mm |
| Net flywheel power | 283 kW (380 hp) to ISO 9249, SAE J1349 and EEC 80/1269 |
| Main system maximum flow, total | 734 L/min (194 gpm) |
| Pilot circuit | 43 L/min at 4,110 kPa |
| Relief pressures | equipment 35,000 kPa, heavy lift 38,000 kPa, travel 35,000 kPa, swing 31,400 kPa |
| Cooling system capacity | 35.5 litre; hydraulic system including tank 570 litre |
Which part in this circuit actually fails
With 283 kW of engine power and 734 L/min of main flow, the heat rejected through this machine’s cooling package is substantial, and the fan motor is the component that has to move it. In practice the failure pattern splits three ways:
- The motor wears internally. Flow bypasses inside the unit instead of turning the shaft. Coolant temperature rises, but the more distinctive sign is hydraulic oil temperature climbing at the same time, because the bypassed flow is dissipating engine power into the oil.
- The pump cannot command full displacement. Fan speed stays low even when the controller is asking for it. The oil temperature alarm comes on with a normal-looking coolant reading.
- The command never arrives. A sensor, a wiring fault or a stuck proportional valve holds the pump at part flow. Nothing mechanical is wrong with either hydraulic unit.
Sequence matters. Test the command first, then measure pump delivery, then judge the motor. Our hydraulic fan motor diagnosis guide et fan pump diagnosis guide set out both procedures, and coolant sensor testing takes ten minutes.
Fitment, and what we do not claim
Supplied for CAT 345D, 345D L, 345D L VG, 349D and 349D L with the C13 engine. Two things we will not repeat from other listings: we cannot confirm this motor for the 374D, which uses a different fan motor set, and we cannot confirm fitment for the 345D2 and 349D2 Series 2 machines. Caterpillar’s own literature for the 345D2 generation differs from the 345D, and the aftermarket data on those machines is inconsistent. Send the plate number and the machine serial prefix and we will check it before quoting.
Fitting and aftercare
Flush the circuit if the old motor produced debris. Fit a new return filter element. Fill the motor casing with clean oil before the first crank. Keep the case drain line unrestricted and running to tank, since back-pressure on the housing is what finishes shaft seals. Bleed with the fan restrained, confirm rotation direction, then prove full fan speed under thermal load and log both temperatures so you have a record.
On cleanliness, the working target for axial and slipper piston units in mobile service is around ISO 4406 18/16/13 on Bosch Rexroth’s mobile hydraulics guidance, and several Cat-numbered fan motors in this family are built by that manufacturer under their own part number.
Pairing and terms
The mating variable displacement fan pump is 295-9426, on its own page here: 295-9426 fan pump. Minimum order one piece on either part, three to six month warranty on new aftermarket units as stated on your proforma invoice, wooden case packing, delivery 5 to 8 working days from payment subject to stock, and inspection photographs before despatch. The full CAT range is under Caterpillar hydraulic fan motor.
