INTERSTATE-MCBEE M-3949688 CP3 RECTANGULAR RING SEAL 03–18 5.9L/6.7L CUMMINS (AFTERMARKET REPLACEMENT)

Product Description

Interstate-McBee M-3949688 — CP3 Rectangular Ring Seal (2003–2018 5.9L / 6.7L Cummins)

High-quality rectangular ring seal for CP3 high-pressure fuel pump applications on 2003–2018 Cummins 5.9L and 6.7L engines. Designed to match OEM form and function for a reliable seal at the pump mounting interface. Sold individually.

• Direct replacement: OE-equivalent dimensions and material for a proper fit.
• Leak prevention: Restores sealing integrity at the CP3 pump interface.
• Service friendly: Ideal when replacing or resealing the CP3 pump.
• Value: Interstate-McBee quality at an aftermarket price.

Specifications

What’s Included

• (1) Rectangular ring seal, P/N M-3949688

Vehicle / Engine Fitment

Verify by engine serial number (ESN) when possible.

• Dodge Ram 2500/3500/4500/5500 with Cummins:
  • 5.9L common-rail (CP3): 2003–2007
  • 6.7L (CP3-equipped): 2007.5–2018
• Note: Not for 2019+ 6.7L trucks originally equipped with CP4.2 pumps.

Install Notes

• Clean mating surfaces thoroughly; do not use sealants unless specified by the service manual.
• Lightly lubricate the seal with clean engine oil or fuel as recommended for installation.
• Torque fasteners to the factory specification and follow the Cummins service procedure.
• After installation, prime the fuel system and check for leaks.

Why Buy From CPP Diesel

• Knowledgeable diesel specialists and ESN-verified fitment support
• Fast shipping and hassle-free returns
• Large inventory of complementary fuel system and sealing components

FAQ

Is this the correct seal for my CP3 pump?

Yes, this rectangular ring seal is intended for CP3-equipped 5.9L (2003–2007) and 6.7L (2007.5–2018) Cummins applications. Verify by ESN for absolute accuracy.

How many do I need?

One seal per CP3 pump service. Replace if the pump has been removed or if a leak is suspected.

Does this fit CP4 pumps?

No. This part is for CP3 applications only.