Product Description
Interstate-McBee M-3906698 Water Pump O-Ring Seal – 1989–2018 5.9L / 6.7L Cummins
Quality replacement water pump O-ring for B-Series Cummins engines. This seal sits between the water pump and the timing cover/housing to prevent coolant leaks. Built to OE form, fit, and function. Sold individually.
- Direct replacement: Matches OE dimensions and material for a proper seal.
- Broad coverage: Fits 5.9L (12-valve & 24-valve) and 6.7L Cummins applications listed below.
- Service friendly: Ideal to replace any time the water pump is removed.
- Value: Interstate-McBee quality at a competitive price.
Specifications
| Brand | Interstate-McBee |
| Part Number | M-3906698 |
| OEM Reference | Cummins 3906698 |
| Location | Water pump to housing (cooling system) |
| Material | Coolant-resistant elastomer (O-ring) |
| Sold As | Each (1 O-ring seal) |
What’s Included
- (1) Water pump O-ring seal, P/N M-3906698
Vehicle / Engine Fitment
Always verify by engine serial number (ESN) when possible.
- 5.9L Cummins (B-Series)
- 1989–1998 12-valve (6BT)
- 1998.5–2007 24-valve (ISB 5.9)
- 6.7L Cummins (ISB 6.7)
- 2007.5–2018 model years
Recommended / Related Parts
- Water Pump (5.9L/6.7L specific)
- Thermostat & Housing Gasket
- Coolant / Additive Package (meeting OEM spec)
- Drive Belt (inspect and replace if worn)
Install Notes
- Drain coolant as required and remove the water pump per the service manual.
- Clean and inspect the sealing groove and mating surface—no nicks or debris.
- Lightly lubricate the new O-ring with clean coolant or compatible assembly lube.
- Ensure the O-ring is fully seated and not twisted before installing the pump.
- Torque fasteners to the manufacturer specification; refill and bleed the cooling system.
- Pressure-test to confirm a leak-free seal.
Why Buy From CPP Diesel
- ESN-verified fitment support from diesel specialists
- Fast shipping and easy returns
- Great selection of B-Series cooling and engine parts
FAQ
Does this O-ring fit both 5.9L and 6.7L Cummins?
Yes—this listing covers common 5.9L (12V & 24V) and 6.7L applications from 1989–2018. Verify by ESN if you’re unsure.
Is the water pump included?
No, this listing is for the O-ring seal only. Consider replacing the water pump if it shows wear or leakage.
Do I need any sealant?
Typically no—use only a light lubricant to aid installation unless your service manual specifies otherwise.
