Product Description
Interstate-McBee MCB6BEXPKS — Expansion Plug Kit — 1989–2002 5.9L Cummins
Complete expansion (freeze/core) plug kit for the 5.9L Cummins B-Series engine family used from 1989–2002. Designed as an OE-equivalent solution to reseal the coolant passages during an engine rebuild or leak repair. Sold as a kit.
- Purpose-built kit: Includes the core plugs commonly replaced during block and cylinder head service.
- OE-style fit and finish: Matches factory dimensions for reliable sealing.
- Durable construction: Quality materials to withstand thermal cycling and corrosion.
What’s IncludedThis kit contains the primary expansion/core plugs required for the engine block and head on 5.9L Cummins B-Series applications. Exact counts and diameters may vary by revision; compare to your engine before installation.
- Block expansion (freeze/core) plugs — assorted diameters
- Cylinder head expansion plugs (as applicable)
- Installation guidance notes (see below)
Vehicle FitmentAlways verify by engine serial number (ESN) for the most accurate fitment.
- Dodge Ram 2500/3500 — 5.9L Cummins
- 12-Valve 6BT: 1989–1998
- 24-Valve ISB: 1998.5–2002
- Other Cummins B-Series applications where this kit is specified (confirm by ESN).
Install Notes
- Clean bores thoroughly; remove corrosion and old sealant.
- Lightly coat plug edges with appropriate sealant if specified by your service manual.
- For cup-style plugs, set them squarely; drive until slightly below flush and evenly seated.
- Replace any damaged or pitted plugs rather than reusing.
- Refill with the correct coolant mixture and pressure-test after installation.
Recommended/Related Parts
- Block heater or replacement block heater plug (if equipped)
- Coolant/antifreeze and distilled water
- Thermostat and gasket (optional while servicing cooling system)
- Water pump (inspect/replace as needed)
Why Buy From CPP Diesel
- ESN-verified fitment support from diesel specialists
- Fast shipping, easy returns, competitive pricing
- Extensive inventory for Cummins B-Series service and rebuilds
FAQWill this kit fit both 12-valve and 24-valve 5.9L engines?Yes. It covers the 5.9L Cummins B-Series used from 1989–2002. For edge cases, verify by ESN.
Do I need any special tools? A suitable driver and sealant (as specified by your service manual) are recommended. A cooling-system pressure tester helps verify a leak-free install.
Can I reuse old plugs? Reusing is not recommended. New plugs provide the best sealing and corrosion resistance.
| Brand | Interstate-McBee |
| Part Number | MCB6BEXPKS |
| UPC | Not specified by manufacturer/seller |
| GTIN | Not specified by manufacturer/seller |
| Shipping Info | Package weight: 0.75 lb (as listed by a reseller). Other shipping dimensions/method: Not specified. |
| Cross Reference | Kit description: “KIT, EXPANSION PLUG 6B”. Kit BOM references (Cummins-style numbers shown by resellers): 3922072, 3007635, 3900956, 3900687, 3920706, 3900955, 3900958. |
| E-Codes | Not specified |
| Prop 65 | WARNING: This product can expose you to chemicals known to the State of California to cause cancer and birth defects or other reproductive harm. For more information: https://www.P65Warnings.ca.gov |
