Cummins 3802375 — Genuine Lower Engine Gasket Set for 4BT / QSB

MPN: 3802375  |  Also Known As: lower gasket set, bottom-end gasket kit  |  Related / Earlier Kits (ID): 3802019, 3802266

Seal the bottom-end right the first time. The genuine Cummins 3802375 Lower Engine Gasket Set services the lower portion of B-Series 3.9L 4BT / QSB3.9 engines (and select QSB4.5/B4.5C). Ideal for overhauls, leak repairs, and swap builds. Contents vary by engine build and must be verified by ESN to ensure a perfect match.

Features & Benefits

• OE sealing materials & profiles engineered for B-Series thermal expansion and clamp loads.
• Comprehensive lower-end coverage (oil pan, timing/front cover, water pump interface, and related seals—contents may vary by ESN).
• Fewer comebacks vs. piecing individual gaskets—kit approach ensures interfaces are renewed together.
• Genuine Cummins quality for durability, fluid compatibility, and fit.

Verified Fitment

Specifications

• Type: Lower engine gasket set (bottom-end seal kit)
• OE Part Number: 3802375
• Typical Interfaces Covered: Oil pan, timing/front cover, water pump interface, miscellaneous lower seals (actual contents vary by ESN)
• Quantity Required: 1 kit per engine

Often Paired With

• Front & rear main seals (verify by ESN/build option)
• Oil pump pickup tube O-ring and oil pan hardware refresh
• Upper engine (head set) if doing a full rebuild

What’s In The Box

• (1) Genuine Cummins Lower Engine Gasket Set (3802375) — contents per ESN

Installation Tips

• Always verify ESN to ensure kit content compatibility (seal types and counts can change by build).
• Clean all sealing surfaces; avoid over-RTV—use only where Cummins specifies.
• Torque fasteners in sequence to spec; check crank endplay and front cover alignment.
• After first heat cycle, inspect for seepage at oil pan and front cover corners.

FAQ

WILL THIS FIT MY 4BT 3.9L?

Yes—3802375 targets 4BT/4B3.9 lower-end sealing. Because contents vary by build year and seal style, confirm by ESN.

WHAT ABOUT QSB3.9 OR QSB4.5/B4.5C?

Many QSB3.9 and some QSB4.5/B4.5C engines use 3802375, but certain years (e.g., “top-hat” seal era) differ. Verify by ESN before ordering.

DOES THIS KIT FIT 5.9L 6BT/ISB TRUCK ENGINES?

No—this kit is for 3.9L platforms. Use the correct 5.9L kit for 12-valve, VP44, or common-rail engines.

WHAT’S INCLUDED?

Typical lower-end interfaces: oil pan gasket, timing/front cover gaskets, water pump/interface seals, and assorted lower seals. Exact pieces vary by ESN.

ARE THERE EARLIER/ALTERNATE KIT NUMBERS?

Yes—earlier 4BT builds may use 3802019 or 3802266. If your engine is pre-update, those kits may be correct.