Descrizione
Caterpillar’s title for this part contains two words that most fan motor listings leave out, and both of them matter when you are fitting one: suction, and slipper piston. The first tells you which side of the cooler the fan sits on. The second tells you what is wearing inside.
Cosa dice il catalogo
505-5179 is listed by Caterpillar as a Suction Fan Slipper Piston Motor, described as powering a suction fan that pulls air through the radiator and oil cooler rather than pushing it. The parts book item name is MOTOR GP-PISTON -FAN, SUCTION, and it is recorded as a component of the suction fan group on the 336 GC, machine prefix HFJ from 00001. Cat’s compatible model list covers the 336 GC, the 336 and the 336 mobile hydraulic power unit.
Suction side or pressure side, and why a buyer should care
A fan mounted on the downstream side of the coolers, pulling air through them, is a suction or draw-through arrangement. A fan on the upstream side, pushing air at them, is a pressure or blower arrangement. Large excavators increasingly use the suction layout, and it changes three practical things.
- What the motor is bolted to. In a suction arrangement the motor sits behind the core pack, in the airstream, exposed to whatever the core has just filtered out. Mounting brackets and seal faces get dirty, and dirt at the seal lip is how a healthy motor starts weeping oil.
- How a blocked core shows up. A suction fan has to work harder to move the same air through a plugged core, so a machine that has been run dirty will have put real load hours into the motor. Cleaning the core is not a cosmetic job on this layout, it is life extension for the part you are about to buy.
- Which way the shaft turns and where the drain goes. Port identity and case drain routing are set up for the direction of rotation. Swap the two and the seal sees pressure it was never meant to see.
We can tell you what Caterpillar states for this number. Whether the equivalent unit on a given machine is a suction or pressure arrangement should be confirmed on the machine itself, and a photograph of the fan shroud answers it in seconds.
Fitment, stated narrowly
Caterpillar’s applicability data puts 505-5179 on the 336 GC with the C7.1 engine, prefix HFJ. Supplier listings extend it to the 345 GC and to a 349 GC, and neither is supported by Cat’s data: the 345 GC motor is 505-5180, and there is no 349 GC entry we could verify for either number. Suppliers also list 598-7826, 512-0949 and 505-5180 as crosses for this part. They are different components, and treating them as interchangeable is how a workshop ends up with a motor that fits the flange and nothing else.
Testing before you replace
A slipper piston motor fails by wearing the interface between the slippers and the valve plate, which shows up as internal leakage: flow arrives, the fan does not speed up, and the energy leaves as heat in the hydraulic oil. Three checks separate that from the alternatives:
- Confirm the command. If the controller is not asking for full cooling, the motor never had a chance. Sensor and signal checks are in our coolant temperature sensor testing guide.
- Measure flow at the motor ports. Short supply points at the fan pump, not the motor.
- Drain-test the motor. Flow coming out of the case drain with the fan commanded to full is the internal leakage figure you need. The procedure is in our guida alla diagnosi del motore ventilatore idraulico.
Montaggio
Flush the circuit if the old motor produced debris, and change the return filter element. Fill the casing with clean oil before the first crank. Route the case drain to tank with no restriction. Match shaft form, flange and port position against the removed unit. Confirm rotation direction with the fan restrained, then clean the core pack, because on a suction layout that is the single cheapest thing you can do to protect the new motor.
Condizioni
Minimum order one piece. New aftermarket units carry a three to six month warranty as stated on your proforma invoice. Bench tested, photographed against your order before packing, wooden case, delivery 5 to 8 working days from payment subject to stock. The pump that feeds this motor is on our 524-0925 page, and the wider range sits under Motore idraulico ventola Caterpillar.
