Description

Caterpillar 320C LU, 320C U 2004 Parts Catalog – Factory OEM Parts Manual

You ever order a hydraulic pump seal kit for a Caterpillar 320C LU and get the wrong one because the aftermarket catalog didn’t tell you which pump group you had? I’ve seen it happen. Then the machine sits for another two days while you wait for the right part. That’s lost money. This 2004 Parts Catalog for the Caterpillar 320C LU and 320C U is the factory document that stops that. 898 pages of exploded views, exact part numbers, and attachment breakdowns. If you maintain any 320C series track excavator powered by the 3066 engine, this PDF belongs on your tablet in the cab.

Engine and Fuel System Coverage – Page 12 and Page 57

Two pages you’ll use often: page 12 for the Engine group and page 57 for the Fuel Tank. On page 12 you get the full engine assembly – block, head, valve train, oil pan – with every gasket, bolt, and seal identified by part number. The 3066 engine uses specific valve components; the factory drawing makes sure you order the right intake or exhaust valve kit. On page 57 the Fuel Tank illustration shows the pickup tube, strainer, and mounting hardware. No guessing if the tank sender fits a standard or high-capacity layout. The manual includes serial number breakpoints so you match the correct illustration to your machine’s build date.

Parts Catalogs vs. Service Manuals: What’s the Difference?

I still see guys trying to use a service manual to find a part number. Wrong tool. A service manual tells you how to remove and install. A parts catalog tells you what to order. This one gives you the Caterpillar-specific part numbers – not aftermarket cross-reference numbers that may or may not fit. The Automotive Industry Overview explains how OEM documentation maintains accuracy across production changes. Caterpillar updates these catalogs when engineering changes happen; this 2004 edition captures the production runs up to serial number APA1-99999 and ALX1-99999 (vehicle) and engine 7JK38735-up. If your machine’s serial falls within those ranges, every part listed is the one you need.

How to Use This 898-Page Document

Open the PDF and look for the MODEL VIEW section in the table of contents. You’ll see groups like Counterweight (page 180), Air Cleaner (page 40), Radiator & Oil Cooler (page 32), and Boom Cylinder (page 252). The alphabetical index in the front helps you find any assembly by name. Under each illustration there’s a caption that tells you which serial numbers the drawing applies to. Parts lists use indentation to show sub-components – for example, under “Engine Cover” (page 160) you’ll find the cover panel, hinge, and latch listed as separate serviceable items. The manual also includes a LIST OF ATTACHMENTS section that covers things like the 186-1227 Additional Gear Train for Auxiliary Pump (page 238), reach booms in 5.7m lengths, and excavation buckets with specific widths and adapter sizes. If you’re retrofitting a hammer or demolition setup, those pages are gold.

3 Reasons to Trust Factory OEM Documentation

First, every part number is verified by Caterpillar – not a third-party translator who guessed. The manual uses factory abbreviations like N/S (Not Serviced) and AS (Assembly) so you know when you have to buy the whole assembly instead of individual components. Second, the captions include effective dates – for example, “D95.05-” means on and after May 1995; “T00.05-” means on and after May 2000. That tells you exactly when a design change happened. Third, the REPLACEMENT ITEMS section lists all filters (air, oil, fuel, hydraulic) by their Cat part numbers: Engine Oil Filter 1R-0739, Fuel Filter 1R-0751, Hydraulic Tank Return Filter 126-2081. No cross-reference, no looking up equivalent. Order the Cat number and you’re done.

Valve and Hydraulic Components – Control Valve on Page 382

The hydraulic system is the heart of any excavator. This catalog covers the Control Valve group on page 382, the Swivel on page 366, the Pump on page 227, and the Capsule Filter on page 242. For the valve, you get the bank sections, relief valves, and spools. If you’re rebuilding a swing drive, page 354 shows the Swing Drive assembly with all bearings and seals. The Boom Cylinder (page 252), Stick Cylinder (page 254), and Bucket Cylinder (page 256) are each broken down individually. Having the factory drawing for the Rod (page 554) and Link (page 554) saves you from ordering the wrong rod seal kit. I’ve seen two different rod diameters on 320C machines; the catalog’s serial number notation is the only way to know which one you’ve got.

FAQ

Can I use this catalog to find part numbers for a 320C that is not LU or U?

If your machine is a standard 320C (no LU or U suffix), some groups may differ. The LU indicates long undercarriage; U indicates utility version. The manual explicitly covers 320C U and 320C LU track-type excavators. For a base 320C, cross-reference the serial number ranges listed inside.

Does this include wiring diagrams or torque specs?

No.

How do I know if my engine serial number is covered?

Engine coverage is 7JK38735-up. If your engine serial falls before that, parts may still be the same, but verify against your machine serial (APA1-99999 or ALX1-99999).

What is the difference between this parts catalog and a service manual like the Caterpillar 320C 2008 Service Manual?

A service manual tells you how to fix it – torque values, removal procedures, diagnostics. A parts catalog tells you what to order. Both are needed. If you also work on other Cat machines, check the Caterpillar C15 2006 Parts Catalog – Factory OEM 884 Pages or the Caterpillar Elevated Sprocket Tractors Parts Catalog – 971 Pages for additional coverage. For a broader understanding of OEM documentation standards, read the Automotive Industry Overview.

Stop guessing which part fits. The factory Caterpillar 320C LU and 320C U Parts Catalog puts every right part number in front of you. 898 pages, OEM-sourced, with exact serial number breakpoints. Access the Factory Manual and keep it on your phone or shop tablet – you’ll wonder how you ever got by without it.