Caterpillar 320D Parts Guide: Seal Kit, Wiring Harness and Electrical Part Numbers

The Caterpillar 320D is one of the most common 20-ton excavators on job sites around the world, and many of them are now old enough to need seal kits, harnesses and electrical parts. This guide collects the 320D part numbers we list in one place, so you can find the right number quickly and check it against your machine before you order.

Everything here is an aftermarket replacement part sold by Topsealkit. Part numbers are used only to show what each part replaces.

Before You Order: Find the Right Number

The 320D was built in several versions (320D, 320D L, 320D LN, 320D RR and 320D LRR), and parts can change with the serial number. The safest way to order is by part number, not by model name alone:

• Seal kits: read the kit or cylinder number on the cylinder tube label, or look it up in your parts manual. The boom, stick and bucket cylinders each use a different kit.
• Wiring harnesses: the number is usually printed on a tag on the harness itself. Note where it runs (main, chassis, cab, fan pump) and the connector count.
• Electrical parts: take the number from the old part's label. For controllers and monitors, also note the engine (C6.4 on most 320D machines).

Not sure? Send us your machine model, serial number and a photo of the label, and we will confirm the match before you pay.

Hydraulic Cylinder Seal Kits for the 320D

These are the cylinder seal kits we list for the 320D family. The "Listed for" column shows which versions each kit is listed for. Click a part number to see the kit, price and stock.

You can also browse all kits in our Caterpillar seal kit collection.

Wiring Harnesses for the 320D

Harness faults on older 320D machines often show up as intermittent warnings, dead gauges or a machine that will not start. These are the 320D harnesses we list:

More harnesses for other CAT models are in our Caterpillar wiring harness collection.

Engine and Fuel System Parts

Cab, Hydraulic Control and Electrical Parts

Signs a Part Needs Replacing

• Cylinder seal kit: oil on the cylinder rod or tube, a cylinder that drifts down when the machine is parked, or slow, weak movement under load.
• Wiring harness: faults that come and go when the machine vibrates, corroded or melted connectors, or chafed insulation.
• Fuel injector: hard starting, rough idle, black smoke or a loss of power.
• Monitor or controller: blank screen, error codes that do not clear, or no communication between the engine and the machine.

Shipping, Warranty and Returns

In-stock parts are dispatched in 1–3 working days. Delivery takes 5–10 days to the US and 7–15 days to other countries, and import duties are included for most destinations. Warranty is 1–12 months depending on the part. If a part has a quality problem, contact us within 14 days of delivery for a replacement or refund.

Questions

Are these parts made by Caterpillar?
No. They are aftermarket replacement parts sold under the Topsealkit brand and are not made or endorsed by Caterpillar.

Do 320D and 320D2 machines use the same parts?
Not always. The 320D2 uses a different engine and many different electrical parts, so always order by part number.

Can I order several kits for a full rebuild?
Yes. Repair shops and dealers can contact us for a quote on multiple kits.

Caterpillar, CAT and all model names and part numbers are trademarks of their respective owners and are used only to identify compatibility. Topsealkit is not affiliated with Caterpillar.