Product Description
Interstate-McBee M-3678603 Turbo Oil Inlet O-Ring — 07.5–18 6.7L Cummins
OEM-style turbocharger oil inlet O-ring engineered by Interstate-McBee for 2007.5–2018 Ram 2500/3500 6.7L Cummins (ISB). Sized to OEM dimensions for a reliable seal at the turbo oil feed fitting, helping prevent leaks and pressure loss during service or turbo replacement.
- Direct replacement: Matches Cummins 3678603 specifications.
- Application-correct: Used on ISB/QSB 6.7 applications; ideal when servicing HE351VE/HE300VG feed fittings.
- Right size, right fit: 0.366" ID × 0.087" C/S for proper groove compression.
- Aftermarket value: Interstate-McBee quality at a lower cost vs OEM-boxed parts.
Specifications
| Interstate-McBee Part | M-3678603 |
|---|---|
| OEM Cross-Ref | Cummins 3678603 |
| Function | Turbocharger oil feed (inlet) O-ring |
| Nominal Size | 0.366" ID × 0.087" cross-section |
| Fitting Context | Common with M12×1.5 oil feed fitting assemblies |
| Warranty | Interstate-McBee new engine parts warranty (up to 24 months) |
What’s Included
- (1) Turbo oil inlet O-ring (M-3678603)
Vehicle Fitment
Always verify by engine serial number (ESN) for edge-case builds.
- Ram 2500/3500 6.7L Cummins (ISB)
- Model Years: 2007.5–2018
- Additional: Also used across ISB/QSB 6.7 platforms where Cummins 3678603 is specified.
Install Notes
- Clean the fitting groove and seating surfaces thoroughly; remove all debris and old elastomer.
- Lightly lubricate the new O-ring with clean engine oil; avoid twists during installation.
- Torque oil feed fasteners per the Cummins service manual; check for leaks after first heat cycle.
Why Buy From CPP Diesel
- Application-specific diesel inventory with expert ESN fitment support.
- Fast shipping, easy returns, and knowledgeable customer service.
- One-stop timing/turbo service parts: oil feed lines, fittings, gaskets, and seals.
FAQ
Will this O-ring fit my 2007.5–2018 6.7L Ram?Yes—this Interstate-McBee M-3678603 matches Cummins 3678603 used on 6.7L ISB applications in 2007.5–2018 Ram 2500/3500. Verify by ESN if your setup has been modified.
Is this an OEM Cummins part?
This is an aftermarket Interstate-McBee part built to OEM-equivalent specs. If you need an OEM-boxed item, order Cummins 3678603.
What are the size specs?
Nominal dimensions are 0.366" inside diameter by 0.087" cross-section, correct for the turbo oil feed fitting groove.
Do I need sealant?
No sealant is used on O-rings. Lightly oil the O-ring and install per the Cummins service manual.
Signs the O-ring is failing?
Oil seepage at the turbo oil inlet, soft/flattened elastomer, or nicks/cuts after disassembly. Replace any time the fitting is removed.
