Most cooling-system questions we get are really two: which part failed, and which number do I order. The first is answered by symptoms — coolant loss, oil temperature spikes, no airflow at the core. The second is answered by numbers checked against live listings, not copied from a forum. This guide maps the cooling stack, the numbers we can verify for the highest-volume Cat and Komatsu excavators, and what each part costs in 2026.
1. The Parts List: What Sits in the Cooling Stack
On a modern excavator or loader the cooling system is a compact stack of three cores — radiator, hydraulic oil cooler and intercooler (air-to-air aftercooler, ATAAC, on turbo machines) — with a suction fan, fan clutch, thermostat, hoses and pressure cap around them. The fan is belt-driven on older machines, hydraulic or electric on newer ones.
- Radiator. Cools the engine coolant. Aluminum core is standard on mid-2000s machines; copper-brass on older builds costs more — see our aluminium vs copper comparison.
- Hydraulic oil cooler. Keeps hydraulic oil in its working range. It shares the radiator's airflow, so a clogged radiator starves it too — details in our oil cooler guide.
- Intercooler / aftercooler. Cools turbocharged intake air. A leak costs power under load long before it shows as overheating — more in our intercooler guide.
- Fan and fan clutch. The clutch engages only when needed; one that never engages means no airflow, one that never releases wastes fuel. Costs are in our cooling fan guide.
- Fan belt, thermostat, hoses, pressure cap. The wear items. Belts crack and glaze, hoses soften and bulge, thermostats stick, and a weak cap lowers the boiling point — turning a healthy radiator into an overheater.
2. Verified Part Numbers: Cat 320D/330D/336D and Komatsu PC200-8
The table lists cooling numbers cross-checked against live listings and our order history (checked August 2026). The 320D, 330D/336D and PC200-8 are the highest-volume excavators on the used market in Africa, the Middle East and Southeast Asia — and the most misquoted on cooling.
| Machine | Part | OEM no. | Notes |
|---|---|---|---|
| Cat 320D / 320DL | Radiator | 326-3870 | Aluminum; also listed for 323D, 324D, 325D, 329 |
| Cat 320D / 321D / 323D | Radiator | 265-3625 | Replaces 312-8338, 481-3475, 265-3624 |
| Cat 330D / 330DL / 336D / 336DL / 336D2 / 340DL | Radiator | 245-9359 | C9 engine |
| Komatsu PC200-8 / PC210-8 / PC230NHD-8K | Radiator | 20Y-03-41651 | Supersedes 20Y-03-42451 |
| Komatsu PC200-8 family | Intercooler | 20Y-03-41131 | Aluminum core; ~$715 listed Aug 2026 |
Each number links to a dedicated product page: Cat 320D radiator 326-3870, Cat 245-9359 radiator (330D/336D), Komatsu PC200-8 radiator 20Y-03-41651. Not in the table: thermostats, fan clutches and belts — they change with fan-drive configuration and build year, so we confirm them by serial. The 320D family's number evolution from 312-8338 to 326-3870 is in our Caterpillar radiator guide.
3. What Cooling Parts Cost (2026 Benchmarks)
Prices below were checked against live listings and our own quotes in August 2026 — a budgeting range, not a quote; your price depends on fitment, core size and freight.
| Part | Aftermarket | OEM reference | Source / note |
|---|---|---|---|
| Radiator, 20-ton class (PC200-8 size) | $250–600 | $900–1,800 | Site benchmark, Aug 2026 |
| Cat 320D radiator 326-3870 | ~$90–500 | — | Amazon listings, Aug 2026 |
| Komatsu PC200-8 intercooler 20Y-03-41131 | ~$715 | — | FridayParts listing, Aug 2026 |
| Fan / fan clutch | $80–450 | ~2× aftermarket | Complete assemblies $150–450 |
| Hydraulic fan motor | $220–600 | — | — |
| Hydraulic oil cooler | $180–650 | 2–3× aftermarket | Dealer pricing |
| Labor per swap | 2–4 hours | Typical workshop time | |
The working rule: a quality aftermarket part runs 30–60% below OEM list for the same fitment. The trap runs the other way too — a radiator priced far below the $250–600 band for this class is usually a thin-core unit that overheats on the first hot day.
4. Failure Signs: Which Part Is Telling You It's Done
Each part fails with its own signature — match the symptom before you order:
- Coolant loss, white crust at seams, bent fins, hairline cracks in plastic tanks — radiator. Small seam leaks can sometimes be welded and blocked cores flushed, but a cracked tank means replacement — see our replacement guide.
- Oil temperature spikes under load, or oil in the coolant — hydraulic oil cooler. Ignoring it is expensive: a $300 cooler failure can become a multi-thousand-dollar pump repair.
- Power loss under load, oily soot at intercooler joints, boost whistle — intercooler or its hoses.
- No airflow at the core when hot, or a fan that roars constantly — fan clutch. A stuck-open clutch wastes fuel; a stuck-closed one cooks the stack.
- Squeal on startup, cracked or glazed belt, soft bulging hoses, hiss after shutdown — belt, hoses and pressure cap. Cheap insurance for a new radiator.
5. Ordering Without Getting the Wrong Unit
The model name is not enough. Both manufacturers changed cooling packages across production years — the 320D family's radiator ran 312-8338 → 481-3475 → 265-3624 → 265-3625/326-3870, and the PC200-8's 20Y-03-42451 was superseded by 20Y-03-41651 — so an early-build radiator may not bolt onto a late-build machine. What we need from you, in order of importance:
- Machine serial number (PIN) — ties the machine to its build spec.
- Photos of the old unit — front, back and mounting brackets — plus any legible number stamped on it, so we can compare core height, tank shape and brackets.
Freight tip: when the radiator, intercooler and oil cooler sit in the same stack, quote them together — one crate, one customs line. We supply aftermarket radiators and cooling parts for Cat, Komatsu, Hitachi, Doosan and Hyundai, fitment-confirmed by serial before dispatch — see the filters & cooling parts catalog or message us directly.
FAQ
Q: Which cooling system parts fail most often on excavators and loaders?
A: Radiators fail most — cracked plastic tanks, blocked or bent fins, seam leaks after years of heat cycling — followed by fan clutches that stop engaging, oil coolers with fin damage, and intercooler boost leaks. Belts and hoses are wear items checked at every service.
Q: What is the radiator part number for a Cat 320D, 330D or 336D?
A: For the 320D family the common aftermarket number is 326-3870 (also listed for 323D, 324D, 325D and 329); early 320D/321D/323D builds use 265-3625, replacing 312-8338, 481-3475 and 265-3624. The 330D and 336D with C9 engine use 245-9359. Confirm against your machine serial before ordering.
Q: How much do excavator cooling system parts cost in 2026?
A: For the 20-ton class: radiators run roughly $250–600 aftermarket against $900–1,800 OEM; fans and clutches $80–450; hydraulic fan motors $220–600; oil coolers $180–650 with dealer OEM 2–3 times that; labor 2–4 hours per swap. Aftermarket parts run 30–60% below OEM list.
Q: How do I order the right cooling part for my machine?
A: Send your machine model, serial number (PIN) and photos of the old unit — front, back and mounting brackets — plus any number stamped on it. We cross-reference the OEM number and confirm fitment before dispatch. Radiator, intercooler and oil cooler in the same stack? Order together — one crate.
Need a Cooling Part Confirmed?
Send us your machine model, serial number and photos of the old part — we cross-reference the OEM number and confirm fitment before you commit. Radiators, oil coolers, intercoolers and fan clutches ship worldwide.
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