129-2413 Piston Motor for CAT 980G Loader, 824G 825G, 3406 Engine

Descripción

Three machines that most parts sellers lump together as loaders, one of which is not a loader at all, and a fan motor that serves all of them. It is a good illustration of why a fitment list has to be read at engine and prefix level rather than at model-name level.

What the machines actually are

Caterpillar’s own literature classifies these three differently. The 980G is a wheel loader. La 824G is a wheel tractor, the large haul-road machine that later became the 824H wheel dozer in Cat’s range. The 825G is a soil compactor. They share the 3406 and 3406C engine family and a cooling package architecture, which is why a single hydraulic motor number covers all three. Calling them all loaders in a parts listing is not a harmless shorthand; it tells a buyer that the writer has not opened the applicability data.

Applicability

Caterpillar’s data attaches 129-2413 to:

• 980G wheel loader, prefixes 9CM and 2KR with the 3406C, and 2SR in older literature, where the item is recorded as a piston motor group.
• 824G wheel tractor, prefix 4SN, 3406C engine.
• 825G soil compactor, prefix 6RN, 3406 engine.

An important distinction that catches buyers out: the 980G Series II is a different machine in the parts data, and its fan motor is 161-8919, not this one. If your loader is a 980G II, read the plate before ordering.

What Caterpillar does not say

Cat’s title for 129-2413 is simply Piston Motor. It does not state which machine function the motor drives, and it does not give a displacement, a pressure rating or a flow figure. The fan-motor role comes from trade parts data, and it is consistent with the physical unit we photograph, which is a compact yellow piston motor with a square flange and no external regulator, exactly what a fixed displacement fan drive motor looks like. We state it that way rather than quoting a specification that nobody has published.

Machine context for the 980G

The 980G is a large wheel loader of roughly 65,638 lb operating weight with a Cat 3406 engine and a cooling system holding about 20.9 gal. We could not find a first-party power figure we would stake a page on for the 980G, so we do not publish one; the numbers circulating on aggregator pages are inconsistent enough that quoting any of them would be misleading.

Why wheel loader fan motors fail in this duty

Loaders run a duty cycle that is unusually hard on a cooling circuit. The engine alternates between full load and idle dozens of times an hour, so a fan that is not metered correctly spends its life either running unnecessarily or not fast enough. Meanwhile the machine is working in loose material: topsoil, aggregate, recycled waste. The core face collects it, airflow drops, oil temperature rises, and the motor is asked to run at maximum displacement against a hotter, thinner oil. That combination, high command plus hot thin oil plus dust, is where the wear starts.

Caterpillar’s answer on its current loaders is instructive. The 950 GC page states that the electronically controlled, hydraulically driven variable speed fan adjusts to meet the machine’s varying cooling requirements, which reduces average fan speed and lowers fuel consumption, noise levels and radiator plugging. That is the modern version of the same problem your 980G has.

Diagnosis and checks

1. Clean the core and re-check temperatures before condemning anything.
2. Confirm the fan reaches speed with the engine at high idle. If it does not, measure flow at the motor ports.
3. Short flow at the ports points upstream at the fan pump, not at this motor. Our fan pump diagnosis guide covers that test.
4. Correct flow with a slow fan and a hot drain line is internal wear in the motor. The procedure is in our fan motor diagnosis guide.
5. Check the case drain routing on reassembly. Casing back-pressure finishes shaft seals, and on loaders the drain hose is often routed where a service technician can pinch it.

Fitting and terms

Prime the casing with clean oil before cranking, fit a new return filter element, and hold cleanliness around ISO 4406 18/16/13 in line with Bosch Rexroth guidance for piston units in mobile service. Minimum order one piece, three to six month warranty on new aftermarket units as stated on your proforma invoice, wooden case, delivery 5 to 8 working days from payment subject to stock. The 980G II and 966H motor is on our 161-8919 page, and the rest of the CAT range is under Caterpillar hydraulic fan motor.