Product Description
Upgrade your valvetrain integrity with the genuine Cummins 3931623 OEM valve tappet (lifter) — engineered precisely for the 1989-1998 B-Series 4BT 3.9 L and 6BT 5.9 L engines. This part restores firm contact between camshaft lobe and tappet surface, delivering the factory-correct geometry and material hardness only the OEM part provides.
This tappet is ideal for rebuilding your 12-valve Cummins engine when replacing the camshaft or refreshing the lifters for extended service life under heavy use. It’s sold **individually** so you can purchase only the quantity needed (12 required for 6BT; 8 required for 4BT) and manage your rebuild budget accordingly.
Fitment Details
- Engine: 4BT 3.9 L (B-Series) — 1989-1998 (8 tappets required)
- Engine: 6BT 5.9 L (12-valve) — 1989-1998 (12 tappets required)
- SOLD INDIVIDUALLY — please order the correct quantity for your engine.
- Not recommended for roller-cam conversions unless explicitly specified.
Cross-Reference / Alternatives
This part supersedes/interchanges with OEM numbers 3901787 and 3925031.
Why Choose OEM?
Using the genuine Cummins lifter ensures the correct contact surface, hardness and geometry — essential when replacing your cam or lifters to maintain performance and longevity. Aftermarket alternatives may appear similar but may compromise valvetrain life in demanding applications.
FAQ
Is this tappet sold as an individual piece or a full set?
The Cummins 3931623 tappet is sold individually — you must order one for each lifter position. For the 6BT 5.9L you will need 12 units; for the 4BT 3.9L you will need 8 units.
Do I have to replace all tappets when installing a new camshaft?
Yes — for optimal life and to prevent premature wear of the new cam lobes, replacing all tappets along with the cam is strongly recommended.
Will this tappet fit my 1994-1998 Dodge Ram 2500/3500 5.9L 12-valve engine?
Yes — this is the correct OEM lifecycle tappet specified for many 1989-1998 5.9L (12-valve) B-Series Cummins engines. Always confirm by engine serial number (ESN) or parts catalog before ordering.
| Specification | Detail |
|---|---|
| Part Number | 3931623 |
| UPC / GTIN | Not publicly listed |
| Shipping Weight | ~0.224 lb (0.101 kg) – per Cummins listing |
| Engine Applications | 4BT 3.9 L & 6BT 5.9 L (B-Series, 1989-1998) |
| Quantity Required | 8 for 4BT, 12 for 6BT |
| Replaces / Interchanges | 3901787 ; 3925031 |
| E-Codes | Not applicable |
| California Prop 65 Warning | None noted by OEM; aftermarket sources suggest possible warning for comparable parts — verify if selling to CA residents. |
| Shipping Info | Ships individually; verify shipping costs at checkout. |
