Caterpillar Buna N O-Ring, PAI 321221 (OEM 1090078), Pack of 6
Used In These Kits
This part is included in 6 engine & overhaul kits — find yours below.
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331150Cat / Caterpillar OIL PAN GASKET KIT In stock -
331152Cat / Caterpillar C15 ENGINE OIL PAN GASKET KIT In stock -
331166Caterpillar C15 In-Frame Gasket Kit In stock -
331230Cat / Caterpillar 3400 SERIES UPPER GASKET KIT In stock -
331238Cat / Caterpillar 3400 SERIES UPPER GASKET KIT In stock -
331421Cat / Caterpillar CENTRAL-LOWER STRUCTURE GASKET In stock - No kits match that search.
Suggested Additional Parts
Commonly sold with this product. These parts are sold separately.
| Brand | PAI Industries |
| Part Category | Seals & O-Rings |
| Sub-Type | O-Ring |
| Engine Make | Caterpillar |
| Engine Model | 3406E · C15 · C16 · C18 |
| Condition | New |
| Stage / Tier | Standard |
Pack of 6.
PAI 321221 is a Buna N o-ring; PAI specifies a 1.475-inch inside diameter and 0.210-inch cross section. The manufacturer-designated reference is Caterpillar OEM 1090078.
Compatible Engines
PAI lists Caterpillar 3406E Series; Caterpillar C15 Engine; Caterpillar C16 Engines; Caterpillar C18 Engine applications. Match the original part number and listed application.
PAI lists these manufacturer references: Caterpillar 109-0078; Caterpillar 1090078; Caterpillar 4F7389; Cummins 4934085; Rockwell (Excel Products) 1205-X-726; Mack 8235-1205X726.
Compare the complete part number and required specification before ordering.
PAI Part #: 321221
OEM References:
- CATERPILLAR 109-0078
- CATERPILLAR 1090078
- CATERPILLAR 4F7389
- CUMMINS 4934085
- ROCKWELL (EXCEL PRODUCTS) 1205-X-726
- MACK 8235-1205X726
Applications:
- CATERPILLAR 3406E SERIES
- CATERPILLAR C15 ENGINE
- CATERPILLAR C16 ENGINES
- CATERPILLAR C18 ENGINE
Warranty: 2.0 year(s)
These catalog references may identify this part or components in an assembly. A listed number alone does not confirm whole-assembly interchange or vehicle fitment. Confirm the required part before ordering.
| Number |
|---|
| 109-0078 |
| 1090078 |
| 4F7389 |
| 4934085 |
| 8235-1205X726 |
| CATERPILLAR 109-0078 |
| CATERPILLAR 1090078 |
| CATERPILLAR 4F7389 |
| CUMMINS 4934085 |
| ROCKWELL (EXCEL PRODUCTS) 1205-X-726 |
| MACK 8235-1205X726 |
| PAI 321221 |
No cross-reference numbers match that search.
Discovery models are listed below. Confirm the complete application and any ESN/CPL or size restrictions before ordering.
Most PAI parts carry a 2-year unlimited-mileage PAI warranty — 3 years on the High Performance tier, 1 year on Excel by PAI. See Warranty & Returns for full coverage terms, or call a specialist to confirm the exact coverage on this part.
PAI published warranty tiers: High Performance — 3-Year · Genuine PAI — 2-Year · Excel — 1-Year, unlimited mileage. The badge beside the price shows this product's recorded term; when no badge is shown, confirm coverage with a specialist.