Product Description
Cummins 3906698 — Genuine Water Pump Rectangular Ring Seal for 5.9L & 6.7L
MPN: 3906698 | Also Known As: rectangular ring seal, water pump seal | Type: Pump-to-block sealing ring
Genuine Cummins rectangular ring seal that seals the water pump to the engine block on B-Series applications. Designed for 5.9L (1989–2007) and 6.7L (2007.5–2018) Ram applications; always confirm by VIN/ESN. Replace this seal whenever the water pump is removed to ensure a leak-free service. Sold individually (1 required per pump).
Features & Benefits
- OE sealing geometry for a perfect pump-to-block interface.
- Coolant/heat resistant elastomer formulated for long life.
- Direct-fit replacement that installs with factory-style pumps (OE or quality aftermarket).
- Prevents leaks & pressure loss that can lead to overheating.
- Backed by Cummins quality and material specs.
Verified Fitment (Automotive)
| Year Range | Engine | Chassis |
|---|---|---|
| 1989–1993 | 5.9L 12V (6BT) | Ram 2500/3500 |
| 1994–1998 | 5.9L 12V (6BT) | Ram 2500/3500 |
| 1998.5–2002 | 5.9L 24V ISB (VP44) | Ram 2500/3500 |
| 2003–2007 | 5.9L ISB (Common-Rail) | Ram 2500/3500 |
| 2007.5–2018 | 6.7L ISB (Common-Rail) | Ram 2500/3500 |
Industrial/Off-Highway: Used primarily across BS3 5.9L B-Series and related ISB/QSB platforms. Verify by ESN before ordering.
Compatibility Notes:
- This seal installs between the water pump and engine block. Replace it anytime the pump is serviced or removed.
- Designed for OE-style pumps; ensure any aftermarket pump follows OEM dimensions.
Specifications
- Part Type: Rectangular ring seal (water pump to block)
- OE Part Number: 3906698
- Cross-References (ID only): Interstate McBee M-3906698; “Seal ring / rectangular” listings
- Quantity Required: 1 per water pump
Often Paired With
- Water Pump Assembly: Cummins 5473238 (popular 5.9/6.7 pump kit)
- Coolant & thermostat: Replace as needed when servicing the cooling system
What’s In The Box
- (1) Genuine Cummins Rectangular Ring Seal (3906698)
Installation Tips
- Clean mating surfaces thoroughly; inspect pump housing and block pocket for nicks or corrosion.
- Lightly lubricate the seal; do not use RTV unless specified by service manual.
- Torque water pump fasteners to factory specification and pressure-test the cooling system after fill.
FAQ
WILL THIS FIT MY 1989–2018 RAM 5.9L/6.7L?
Yes—this rectangular ring seal is used on 5.9L (’89–’07) and 6.7L (’07.5–’18) Ram applications; always confirm by VIN/ESN.
WHERE DOES THIS SEAL GO?
Between the water pump and the engine block to create a leak-free joint.
DO I NEED A NEW SEAL EVERY TIME?
Yes. Replace the seal anytime the water pump is removed or replaced.
IS THIS THE SAME AS AN O-RING?
No—this is a rectangular ring seal specifically sized for the Cummins B-Series water pump interface.
WILL IT WORK WITH AFTERMARKET PUMPS?
Yes, provided the pump matches OEM geometry; most quality aftermarket pumps do.
