Caterpillar Radiator Guide: Models, Part Numbers & Replacement Costs

📅 Published: August 26, 2026✍️ By CN Machinery

Of all the cooling parts on a Cat excavator, the radiator is the one buyers get wrong most often — not because the part is complicated, but because Caterpillar changed radiator part numbers several times within the same model family. A 320D built in 2008 and a 320D built in 2014 can carry different radiators. This guide covers the part numbers we can confirm for the high-volume Cat excavators, what they cost, and the one piece of information that removes all guesswork: your machine serial number.

1. Cat Radiator Part Numbers at a Glance

The table lists radiators confirmed against live aftermarket listings (checked August 2026). Treat it as a planning tool — the final number for your machine is confirmed by serial.

Machine	Engine	Radiator part no.	Notes
Cat 320D / 320DL	C6.4	326-3870	Aluminum; also listed for 323D, 324D, 325D, 329
Cat 320D / 321D / 323D	C6.4 / C4.2	265-3625	Aluminum; replaces 312-8338, 481-3475, 265-3624
Cat 320C / 320D / 323D	3066 / C6.4	378-6178	Water tank radiator, listed for all three
Cat 330D / 336D / 340D	C9	245-9359	Listed for 330D, 330DL, 336D, 336DL, 336D2, 340DL
Komatsu PC200-8 (for comparison)	SAA6D107E-1	20Y-03-41651	Same 20-ton class; supersedes core 20Y-03-42451

Notice the pattern: three different numbers for the 320D alone. That is why our 320D radiator page asks for your serial number rather than quoting one universal fit.

2. Why the Part Number Alone Is Not Enough

Cat radiators are matched to the cooling package of the build: which hydraulic oil cooler it pairs with, whether the air-conditioning condenser mounts on the same frame, and which fan shroud variant the machine left the factory with. Across the 320D family, aftermarket listings show the supersession running roughly 312-8338 → 481-3475 → 265-3624 → 265-3625/326-3870, and a radiator from an early build may not bolt onto a late build.

What we ask for on every radiator order:

• Machine serial number (PIN) — this is the single most reliable fitment key.
• Photos of the old radiator — front, back, and both mounting brackets; we compare core height, tank shape and fitting positions.
• Any number stamped on the tank or core — if the old unit is still readable, we cross-reference it directly.

With those three things, a correct replacement is routine. Without them, even a correct part number can arrive with the wrong mounting — and cooling packages are not return-friendly on a cross-border order.

3. Failure Signs and When to Replace

Cat radiators fail in predictable ways: coolant loss from cracked plastic tanks or split seams, wet corners or dried coolant stains on the fins, heavy fin damage from stones and wash-down pressure, and overheating under load that a clean radiator still cannot cure. The full diagnostic list is in our radiator failure signs guide — the short version: if you are topping up coolant weekly or the temperature gauge creeps at load, the core is already beyond repair and replacement is the economic call.

Repair (rodding, tank replacement, re-coring) makes sense for copper-brass radiators on older machines; aluminum cores are usually cheaper to replace than to re-core. Our radiator replacement guide walks through both paths with numbers.

4. What a Cat Radiator Costs

Option	Price range	Source / note
Aftermarket radiator, 20-ton class (320D/PC200-8 size)	$250–600	Established aftermarket range; core size and oil-cooler combo drive the spread
Cat 320D radiator 326-3870, aftermarket listings	~$90–500	Amazon listings, Aug 2026, multiple sellers
OEM radiator, 20-ton class	$900–1,800	Dealer list price territory — varies by region
Komatsu PC200-8 intercooler 20Y-03-41131 (cooling-package reference)	~$715	FridayParts, Aug 2026

Two notes on the numbers. First, copper-brass cores transfer heat better than aluminum — 401 vs 237 W/(m·K) — but they cost more and weigh more, and most Cat excavators built since the mid-2000s left the factory with aluminum anyway; the trade-off is covered in our aluminium vs copper guide. Second, always add freight, coolant and labor to the part price — a radiator is heavy and awkward to ship, which is why bundling it with other parts in one crate cuts your landed cost noticeably.

5. How to Order from CN Machinery

We supply aftermarket radiators and complete cooling-package parts (radiators, hydraulic oil coolers, intercoolers, fans, fan clutches) for Cat, Komatsu, Hitachi, Doosan and Hyundai excavators, loaders and dozers. Stock parts dispatch in 3–7 days, FOB Shanghai or CIF to your port. Because radiators are serial-matched, send us the three items from Section 2 and we confirm the number before you commit — see the Cat 320D radiator 326-3870 page for a worked example, or browse the full parts catalog. If you are ordering a radiator, it is usually worth quoting filters and seal kits in the same container — the freight math favors it.

FAQ

Q: What is the radiator part number for a Cat 320D?
A: The common aftermarket number is 326-3870 — an aluminum radiator listed for the 320D, 323D, 324D, 325D and 329 families. Earlier 320D builds used 312-8338, then 481-3475 and 265-3624; aftermarket listings show 265-3625 as the replacement for all three. Confirm by serial before ordering.

Q: How much does it cost to replace a Cat excavator radiator?
A: For a 20-ton class excavator, roughly $250–600 for a quality aftermarket radiator versus $900–1,800 OEM. Cat 320D aftermarket radiators (326-3870) are listed from about $90 to $500 on Amazon as of August 2026. Freight, coolant and labor are extra.

Q: Can I fit an aluminum radiator to an older Cat machine?
A: Usually yes, if the mounting points match. Most Cat excavators built since the mid-2000s came with aluminum cores, so aluminum is the standard replacement. Copper-brass transfers heat better (401 vs 237 W/mK) but costs and weighs more.

Q: How do I confirm the right radiator before ordering?
A: Send the machine serial number, photos of the old radiator and any number stamped on the tank or core. Cat changed radiator numbers across production years, so the model name alone is not enough.