Cummins 3938156 — Genuine Timing Gear Housing Gasket for 5.9L B-Series

MPN: 3938156  |  Also Known As: timing gear case housing gasket, gear housing gasket

Genuine Cummins gasket that seals the gear housing to the engine block on B-Series engines. This is the correct OE replacement for 1989–2002 Ram 5.9L (12V & 24V/VP44). Replace anytime the gear housing is removed to address leaks, perform KDP service, or reseal the front of the engine.

Features & Benefits

• OE sealing material & profile for reliable leak prevention.
• Exact-fit between gear housing and block—no trimming or guessing.
• Prevents oil seepage that can contaminate belts and accessories.
• Ideal during KDP fixes and any timing case service.
• Backed by Cummins quality for durability and longevity.

Verified Fitment (Automotive)

Industrial/Off-Highway: Used primarily on BS3 5.9L B-Series engines—verify by ESN prior to ordering.

Specifications

• Type: Gear housing-to-block gasket (timing gear case housing)
• OE Part Number: 3938156
• Quantity Required: 1 per engine (sold individually)
• Position: Front gear housing (between housing & block)

Often Paired With

• Front cover gasket (’94–’02): 3918673
• Gear housing dowel pin: 3900257 (KDP-related service)
• KDP kit (’89–’02): common preventative upgrade during reseal
• Timing gear case housings: 3920758 (’89–’93), 3936256 (’94–’98) — verify by ESN

What’s In The Box

• (1) Genuine Cummins Timing Gear Housing Gasket (3938156)
• Sealants/hardware not included.

Installation Tips

• Thoroughly clean mating surfaces; avoid scratching aluminum housing.
• Dry-fit and align dowel pins; follow Cummins torque sequence/spec.
• Best practice: inspect/secure the killer dowel pin (KDP) while the case is open.
• Run engine and check for leaks after warm-up; re-torque if required by service manual.

FAQ

WILL THIS FIT MY 1989–2002 5.9L CUMMINS RAM?

Yes—this is the OE gear housing gasket for most 1989–2002 5.9L applications. Some catalogs list 1994–2002; if you have an early 12V (’89–’93), confirm by VIN/ESN.

IS THIS THE FRONT COVER GASKET?

No—this seals the gear housing to the block. The front cover gasket (e.g., 3918673 on ’94–’02) is separate.

WHEN SHOULD I REPLACE THIS GASKET?

Anytime the gear housing is removed (timing work, KDP repair, leak repair). It is not reusable.

IS THIS A GENUINE CUMMINS PART?

Yes—OE Cummins part 3938156.

DO I NEED SEALANT WITH THIS GASKET?

Follow Cummins service procedures. Some spots may call for a thin film of approved sealant at corners/joints.