Description

Caterpillar 320C, 320CL Parts Catalog – 928 Pages of OEM Part Numbers for the 3066 Engine

You own a Caterpillar 320C or 320CL. You need a bracket for the alternator mounting, a new alarm for the travel alarm, or a seal kit for the hydraulic pump. You order from a parts house, wait three days, and get the wrong thing. Now the machine is down another week. A factory Parts Catalog stops that. This one has 928 pages of exploded views and genuine part numbers – not a condensed aftermarket list that leaves out the washers and locknuts you always forget.

What You Get in 928 Pages

Every group is broken down by system. The alternator mounting group (page 4 of the PDF) shows you 12 separate parts: plate, puller, three washers, a specific 30u202fmm bolt, two 20u202fmm bolts, a lockwasher, and so on. Part numbers are right there – 178‑6597 for the plate, 096‑2501 for the washer. No cross-referencing a third-party website. You get the same data the dealership counter uses. The electrical section starts at page 2 with the travel alarm group (alarm GP-travel, part 3T‑1815) and covers everything including the wire assembly, receptacle kit, terminals, and pins. The 3066 engine – the heart of both the 320C and 320CL – has its own dedicated section. This catalog does not include hydraulic system numbers beyond those that bolt to the engine (like the alternator), but for engine and electrical parts, it’s complete. You can also find related training material in the Caterpillar 312C 315C 320C 322C 325C Technical Training manual if you need subsystem theory.

Parts Breakdown: From Alarm GP-Travel to Alternator Mounting

The first pages of the PDF show a typical group structure. Take the alternator mounting group (part of 1626178 and 1838198). You get an exploded diagram with item numbers, then a table that lists each item, its part number, quantity, and description. Example: item 2 is a puller, part 178‑6600. Item 10 is a ring, part 178‑6601. That level of detail saves you from ordering a whole assembly when you only need a $2 washer. The travel alarm group (group 1831037) includes a bolt, washer, clip, alarm, wire assembly, receptacle kit, and terminals. Every nut, bolt, washer, and seal is listed. If your shop expects you to pull parts from a bin, this catalog gives you the exact Caterpillar-supplied part number so you can order from any dealer or cross-reference to a quality aftermarket supplier without guessing.

How Do I Identify the Correct Part Number?

Each group has a title and a part number at the top (like 1831037 for the travel alarm). The table below lists item numbers, then NPR (not replaceable separately? Actually, NPR in the OCR means the part is not sold separately – the column is “NPR” status). The manual uses standard Caterpillar notation: if NPR appears, you must order the entire group. Otherwise, you can order the individual part. The column headings are: Item No., NPR, Part Number, Quantity, Description. That’s it. Five columns. No confusion. You read the exploded view, find the item, match it to the row, and write down the part number. If the part is superseded, the manual does not list supersessions – that’s what a dealer lookup tool does. But for the original part as built, this document is authoritative. For the service procedures associated with these parts, you’ll want the Caterpillar 320C 320C L 2004 Service Manual or the Caterpillar 320C 2001 Service Manual depending on your machine’s year.

Verify Part Numbers Before Ordering

Before you call the parts counter, pull this catalog. Write down the part number, the quantity, and the group number. Then call. That saves everyone time. If the counter person tells you the part is obsolete, you have the original number to give them for a supersession search. I’ve seen too many guys order a “similar” bolt from a bin and end up with a stripped thread because the grade was wrong. This catalog lists bolts by length (e.g., L=20mm, L=30mm, L=135mm) and includes lockwashers and flat washers. Always check the quantity field – sometimes you need 2, sometimes 1. The group 1831037 alarm assembly calls for 2 bolts (7X‑2538) and 2 washers (8T‑4224). Order that, and you’re done. For context on why standardized part numbering matters, you can read the Automotive Industry Overview or any Automotive Industry Overview article – the same logic applies to heavy equipment supply chains.

OEM Documentation: The Only Source You Should Trust

Aftermarket parts catalogs often skip the small parts: the clip, the washer, the terminal pin. They assume you already know. You don’t. This Caterpillar factory print includes every piece that came on the machine from the factory. The PDF is a direct scan of the original Parts Catalog – no third-party editing, no re-typed numbers that might have transposed digits. The 3066 engine parts are listed in the same order Caterpillar’s own parts system uses. If you’ve ever been burned by an aftermarket manual that listed part number 8T‑4223 as a bolt instead of a washer, you know why OEM matters. That washer (8T‑4223) is a hardened flat washer for the alternator mounting. Wrong part, and you’ll have a loose alternator within 50 hours.

Frequently Asked Questions

Does this catalog include hydraulic system parts like pumps and cylinders?

The catalog focuses on the 3066 engine and its directly attached components, plus the electrical system (alarms, alternators). It does not cover the hydraulic pumps, swing gear, or undercarriage. For hydraulic system parts, you need the separate Caterpillar 320C Hydraulic Parts Catalog. This one covers everything from the flywheel to the fan, including the alternator and starter groups.

Are the part numbers in this catalog still current for ordering today?

Part numbers listed are the original assembly numbers for the machine as built. Some may have been superseded. Use these numbers as a starting point – your Caterpillar dealer can run the supersession. The catalog itself is not updated with field changes.

How do I find a specific part, like an alternator pulley?

Go to the alternator group (group 2128622). The exploded view shows item 2 as the pulley, part 5I‑8072. The table lists it with quantity 1. Write that number down.

What if I need a part that has “NPR” in the catalog – can I still order it individually?

NPR means not replaceable separately from the group. You must order the full group assembly. For example, the travel alarm group (1831037) has an NPR on the wire assembly – you buy the whole alarm assembly if you need that wire. Ignoring NPR will get you a partial order that doesn’t fit.

You’ve got the machine, the tools, and the experience. Now get the part numbers that match. Access the Factory Manual from AutoRepairManuals and keep it in your shop computer. Next time you need an alternator bracket or a travel alarm clip, you’ll have the number in 30 seconds instead of an hour on hold with the parts counter.