Product Description
Keep your 5.9L Cummins fuel system dry and leak-free with the CUMMINS 3918188 OEM 8MM FUEL SYSTEM SEALING WASHER. This genuine Cummins bonded sealing washer is designed for the fuel filter bleed screw and injector return line banjo connections on 1989–1998 Dodge Ram 2500/3500 trucks with the 5.9L 12-valve engine, as well as other B-series/industrial applications. Engineered to OEM specs, it restores a positive seal where cheap copper or generic washers often seep, helping maintain clean starts, stable idle, and proper fuel system pressure.
Why Choose Genuine Cummins 3918188?
- Direct-fit 8mm fuel system sealing washer for Cummins B-series engines.
- Correct bonded design for fuel filter bleed screw and injector return banjo joints.
- Prevents fuel seepage and air intrusion that can cause hard starts and rough idle.
- Genuine Cummins quality – no guessing on thickness, hardness, or fit.
- Perfect service item when replacing fuel lines, banjo bolts, or return hardware.
Fitment Details
This sealing washer is commonly used on:
- 1989–1998 Dodge/Ram 2500 & 3500 with 5.9L 12-valve Cummins (B-series).
- Fuel filter housing bleed screw (banjo connection).
- Injector return line banjo connections (typically two washers per joint).
- Additional B-series/industrial engines such as 4BT3.9, 6BT5.9, ISB3.9/4.5 and QSB variants – always verify by ESN for non-automotive applications.
On most 5.9L 12V truck applications, you will use two 3918188 washers per banjo connection – one on each side of the fitting. Always replace washers any time the connection is opened to avoid leaks.
Cross-Reference & Related Cummins Parts
Common cross-reference and related part numbers for this sealing washer include:
- Cummins 3903728 – related sealing washer reference in heavy-duty catalogs.
- Interstate-McBee M-3918188 – aftermarket equivalent reference number.
For complete, all-OEM Cummins fuel system service on your 5.9L 12-valve, pair this washer with these genuine Cummins parts available at CPP Diesel:
- CUMMINS 3282437 OEM AFC BOOST REFERENCE HOSE (AIR FUEL CONTROL TUBE) – 5.9L 12V (1989–1993) – VE-pump boost reference line that uses (2) sealing washers at its banjo connections.
- CUMMINS 3924726 OEM FUEL RETURN CHECK VALVE – RAM 5.9L 12V (1989–1998) – mounts on the fuel filter housing; service it with fresh sealing washers to stop seep leaks.
- CUMMINS 3905707 OEM VE INJECTION PUMP FUEL RETURN LINE (OVERFLOW/DRAIN) – 5.9L (1989–1991 NON-INTERCOOLED) – VE pump overflow/return line where fresh washers help ensure a leak-free install.
Installation Notes
- Use two washers per banjo joint (one under the bolt head and one under the fitting), where specified.
- Never reuse old sealing washers – once crushed, they no longer seal correctly.
- Clean the banjo bolt, fitting faces, and mating surfaces thoroughly before assembly.
- Torque to factory specifications and recheck for seepage after the first heat cycle.
- Prime the fuel system after opening any line and verify there are no bubbles or leaks.
Specifications for cummins 3918188
| Attribute | Value |
|---|---|
| Brand | Cummins Genuine Parts |
| Cummins Part Number | 3918188 |
| Type | 8mm fuel system sealing washer (banjo-style, bonded) |
| Primary Applications | Fuel filter bleed screw & injector return line banjo connections on 5.9L 12-valve Cummins; also used on other B-series/industrial engines where specified |
| Engine Compatibility (Typical) | 5.9L 12V Cummins (1989–1998 Ram 2500/3500); broader coverage for 4BT3.9, 6BT5.9, ISB and QSB engines where called out by ESN |
| Material | Bonded metal/rubber sealing washer (OE-style) |
| Outer Diameter | Approx. 8 mm ID banjo washer (application-specific) |
| GTIN | Not specified by manufacturer |
| UPC | Not specified / does not apply |
| Cross Reference | 3903728, M-3918188, equivalent heavy-duty aftermarket sealing washers |
| E-Codes | Not applicable (hardware component) |
| Shipping Weight (each) | Approx. 0.002 lb (ships as a very small parcel item) |
| Shipping Method | Standard ground / small package |
| Country of Origin | Typically USA (verify per current Cummins packaging) |
| California Prop 65 | No specific Prop 65 warning listed for this part |
FAQ
WILL THIS FIT MY 1989–1998 5.9L CUMMINS RAM?In most cases, yes. Cummins 3918188 is the common 8mm sealing washer used on the fuel filter bleed screw and injector return line banjo fittings for 1989–1998 Dodge/Ram 2500/3500 trucks with the 5.9L 12-valve Cummins. If your fuel system has been modified or you are working on an industrial/medium-duty application, verify by engine serial number (ESN) or existing part number.
HOW MANY 3918188 WASHERS DO I NEED?
Plan on at least two washers per banjo connection (one on each side of the fitting). A full injector return line refresh or filter housing service often uses several washers, so it’s smart to order extras to cover every joint and keep a couple in the toolbox.
CAN I REUSE MY OLD SEALING WASHERS?
No. Sealing washers are designed to crush once to create a tight seal. Reusing old washers is a common cause of weeps and leaks around the banjo bolt. Always install new 3918188 washers anytime the connection is loosened or removed.
WHERE EXACTLY IS THIS WASHER USED ON THE TRUCK?
Typical 5.9L 12-valve truck locations include the fuel filter housing bleed screw and injector return line banjo connections. Some industrial and medium-duty B-series engines may use this washer at additional fuel system fittings. Always match against the original washer or consult Cummins documentation for non-automotive engines.
IS THIS A GENUINE CUMMINS PART?
Yes. This is a genuine Cummins 3918188 sealing washer sourced through CPP Diesel. Buying OE hardware ensures the correct size, material, and sealing performance compared to generic hardware-store washers.
