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CUMMINS

CUMMINS 3921640 OEM VALVE STEM SEAL – RAM 5.9L 12-VALVE (1989–1998)

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SKU:
CUM3921640
MPN:
3921640
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  • CUMMINS 3921640 OEM VALVE STEM SEAL – RAM 5.9L 12-VALVE (1989–1998)
  • CUMMINS 3921640 OEM VALVE STEM SEAL – RAM 5.9L 12-VALVE (1989–1998)
  • CUMMINS 3921640 OEM VALVE STEM SEAL – RAM 5.9L 12-VALVE (1989–1998)
  • CUMMINS 3921640 OEM VALVE STEM SEAL – RAM 5.9L 12-VALVE (1989–1998)
  • CUMMINS 3921640 OEM VALVE STEM SEAL – RAM 5.9L 12-VALVE (1989–1998)
$9.69

Description

Genuine Cummins

Cummins 3921640 — Valve Stem Seal (Intake & Exhaust)

MPN: 3921640  |  Also Known As: valve stem oil seal  |  Cross-Refs (ID only): 3901097, 3921639

Genuine Cummins valve stem seal for 5.9L 12-valve applications. Restores proper oil control at the valve guide to reduce oil consumption and exhaust smoke. Sold individually; 12 required per engine. :contentReference[oaicite:0]{index=0}

Why This Part

  • OE sealing geometry for long service life and clean combustion.
  • Direct-fit replacement for 1989–1998 Ram 5.9L 12-valve (verify by VIN/ESN).
  • ✓ Helps cut oil consumption and startup smoke from worn seals.
  • ✓ Works on both intake and exhaust valves (12 total per engine). :contentReference[oaicite:1]{index=1}
OE Fit Stock Replacement 12 Per Engine

Quick Specs

Type Valve stem oil seal (intake & exhaust)
OE Part # 3921640
Qty Required 12 per engine (sold individually)
Cross-References 3901097, 3921639 (for identification)

Verified Fitment (Automotive)

Year RangeEngineChassis
1989–1998 5.9L 12-Valve (6BT) D/W 250–350 (’89–’93), Ram 2500/3500 (’94–’98)

Industrial/Off-Highway: Used on many B-Series applications (4B/6B/ISB/QSB). Always confirm by ESN. :contentReference[oaicite:2]{index=2}

Often Paired With

  • Valve Spring Compressor (12V): XDP XD312
  • Valve Spring Keepers: Cummins 3900250
  • Valve Cover Gasket: Cummins 3930906

Popular combos taken from XDP’s “Frequently Bought Together.” :contentReference[oaicite:3]{index=3}

What’s In The Box

  • (1) Genuine Cummins Valve Stem Seal (3921640)
  • Tools/gaskets sold separately (see “Often Paired With”).

Install Tips

  • Replace all seals during valve service; inspect guides for wear.
  • Use the proper installer; do not nick the sealing lip.
  • Torque rockers to spec; verify lash after reassembly.

FAQ

WILL THIS FIT MY 1989–1998 5.9L 12-VALVE CUMMINS?

Yes—this is the OE valve stem seal used on 1989–1998 Dodge/Ram 5.9L 12-valve engines. Verify by VIN/ESN if components have been changed. :contentReference[oaicite:4]{index=4}

HOW MANY SEALS DO I NEED?

There are 12 valves on the 12-valve engine—order 12 seals for a complete set. :contentReference[oaicite:5]{index=5}

ARE THESE FOR INTAKE AND EXHAUST?

Yes—3921640 is used on both intake and exhaust valves. :contentReference[oaicite:6]{index=6}

WHAT ARE COMMON CROSS-REFERENCE NUMBERS?

Common identifiers include 3901097 and 3921639 (for cataloging/ID only). :contentReference[oaicite:7]{index=7}

DO THESE FIT OTHER CUMMINS B-SERIES ENGINES?

Yes—this seal appears across many 4B/6B/ISB/QSB applications in industrial/off-highway use. Always verify by ESN. :contentReference[oaicite:8]{index=8}

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Additional Information

Vehicle Year:
1989,1990,1991,1992,1993,1994,1995,1996,1997,1998
Vehicle Make:
DODGE
ENGINE:
5.9L
Part Type:
Valve Seals
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