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)

Industrial/Off-Highway: Used primarily on Tier-1 5.9L B-Series configurations—verify by ESN before ordering.

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.