Two fuel filters.
The 2018 Ram heavy-duty lineup with the 6.7-liter Cummins Turbo Diesel uses a two-filter fuel filtration system: a primary fuel filter with water separator and a downstream secondary fuel filter. This configuration is designed to remove water and particulates before fuel reaches the high-pressure common-rail injectors, helping prevent injector damage and ensuring consistent performance. The core count is two filters, though some service guides reference related components like a water-in-fuel sensor as part of the filtration system.
What are the two fuel filters and where are they located?
The system comprises two filter elements in the fuel filtration module. Here’s a quick breakdown of their roles and placement:
- Primary fuel filter with water separator — located in the engine bay, typically near the frame rail, and accessible for draining water as needed.
- Secondary fuel filter — positioned downstream from the primary, providing finer filtration to protect the injectors and high-pressure pump.
These two filters work in series to clean the fuel before it reaches the common-rail system. Regular inspection and timely replacement are essential for maintaining performance and avoiding fuel contamination issues.
Maintenance and service reminders
Before you review how to maintain this two-filter setup, note that intervals can vary by model year, fuel quality, and operating conditions. Always follow the OEM maintenance schedule in the owner's manual or a Ram service bulletin. Below is a general outline of what to monitor and when to service:
- Check the water separator for water and drain as needed. If equipped with a water-in-fuel warning, address it promptly.
- Replace the primary filter with water separator at the recommended service interval.
- Replace the secondary fuel filter at the recommended service interval, which is typically aligned with the primary filter schedule or per manual.
- Inspect the filter housing for leaks and ensure correct seating of new filters and o-rings.
Maintaining both filters helps protect the fuel system and maintain engine performance, especially in dirty or high-water conditions.
Summary
In 2018, the Ram 2500/3500 with the 6.7L Cummins diesel uses two fuel filters: a primary filter with water separator and a secondary filter downstream. Regular maintenance per the owner's manual is essential to prevent water contamination and injector damage, and to keep the engine running smoothly.