Product Description
Cummins 3990732 — Genuine Tappet / Pushrod Cover for 5.9L 12-Valve
MPN: 3990732 | Also Known As: tappet cover, pushrod cover, side cover | Supersedes: 3927916, 3911821, 3910819
Genuine stamped-steel side cover that encloses and protects the pushrods on the 5.9L 12-valve Cummins. Restores proper sealing and appearance where the original cover may have warped, rusted, or leaked. Direct-fit for 1989–1998 12V. Sold individually (1 per engine).
Features & Benefits
- OE construction for perfect fitment and long-term sealing.
- Corrosion-resistant finish to handle heat cycles and oil exposure.
- Stops seepage when paired with a fresh tappet-cover gasket and grommets.
- Direct replacement—reuses factory hardware where applicable.
- Backed by Cummins quality for durability and service life.
Verified Fitment (Automotive)
| Year Range | Engine | Chassis |
|---|---|---|
| 1989–1993 | 5.9L 12V (6BT) | Ram 2500/3500 |
| 1994–1998 | 5.9L 12V (6BT) | Ram 2500/3500 |
Industrial/Off-Highway: Used primarily on Tier-1 5.9L B-Series configurations—verify by ESN before ordering.
Compatibility Notes:
- Not for 24-valve (1998.5–2002) or 2003+ common-rail engines. Those use different covers/gaskets.
- Always install with a new tappet-cover gasket and bolt grommet seals to prevent leaks.
Specifications
- Type: Tappet / Pushrod Side Cover
- Material: Stamped steel
- OE Part Number: 3990732
- Supersedes: 3927916, 3911821, 3910819
- Quantity Required: 1 per engine (sold individually)
Often Paired With
- Tappet-cover gasket: Cummins 3284623
- Bolt grommet seal: Cummins 3900267 (set as needed)
- Brake-clean & Scotch-Brite: clean mating surfaces before install
What’s In The Box
- (1) Genuine Cummins Tappet / Pushrod Cover (3990732)
- Gasket and grommets sold separately (see “Often Paired With”).
Installation Tips
- Remove old gasket and residue; degrease both surfaces thoroughly.
- Install a fresh 3284623 gasket and 3900267 bolt grommets; torque evenly in sequence.
- After heat cycle, recheck fasteners and inspect for seepage.
FAQ
WILL THIS FIT MY 1989–1998 5.9L 12V CUMMINS RAM?
Yes—3990732 is the OE side cover for 1989–1998 12-valve 5.9L trucks. Confirm by VIN/ESN if unsure.
DOES THIS INCLUDE THE GASKET AND GROMMETS?
No—order gasket 3284623 and bolt grommet seals 3900267 separately.
WILL THIS FIT 24-VALVE (1998.5–2002) OR 2003+ COMMON-RAIL ENGINES?
No—those engines use different covers. This part is for 12-valve applications only.
HOW CAN I TELL IF MY COVER IS LEAKING?
Oil residue down the side of the block, burning-oil smell, or drips near the cover seam usually indicate a failed gasket or warped/rusted cover.
IS THIS AN OEM CUMMINS PART?
Yes—genuine Cummins 3990732, stamped steel, direct replacement.
