The Ram 3500 diesel uses two fuel filters: a primary water-separator filter and a secondary inline filter. In most trucks, the primary is mounted on the driver’s side of the engine bay, while the secondary runs along the fuel line to the injection pump. Exact locations can vary by year, cab configuration, and options.
This article outlines where to look, how to identify each filter, and how to service them, with notes on year-to-year differences and VIN-specific diagrams to help you locate the components accurately.
Common fuel-filter arrangement
Before you begin work, know that the 6.7-liter Cummins in the Ram 3500 uses two filters in sequence to keep fuel clean. Here are the likely locations you’ll find them under the hood:
- Primary fuel filter (water separator): typically on the driver’s side of the engine bay, mounted to a bracket near the firewall or inner fender. It is a larger canister and will usually have a drain valve to remove water.
- Secondary fuel filter: inline along the fuel supply line to the high-pressure pump, usually installed higher on the engine or along the valve-cover area. This filter is smaller and may be housed in a compact assembly.
Note: Exact mounting can vary by year and body style; always verify with the owner’s manual or a service manual for your VIN.
Identifying the filters
Use these tips to tell them apart: the primary water separator is the larger housing with a drain; the secondary is the inline filter along the fuel line, often located closer to the injection pump.
Maintenance and replacement tips
Proper servicing involves replacing filters at the intervals specified by Ram and ensuring the water separator drain is emptied when water is present. Use OEM filters and follow the correct priming procedure after replacement.
What to do if you can't locate them
If the two-filter layout isn’t obvious, consult your vehicle’s service manual or contact a Ram dealer. VIN-specific diagrams can show the exact mounting points for your truck’s year and configuration.
Summary
The Ram 3500 diesel relies on two fuel filters—primary water separator and secondary inline—located under the hood: typically the primary on the driver’s side and the secondary along the fuel line to the injection pump. Always confirm exact positions for your year and cab configuration and follow the manufacturer’s service guidelines when replacing filters.
How many fuel filters does the Ram 3500 have?
The 2007.5–2024 Ram 2500/3500 runs a dual filtration system — both filters must be changed together. This 30-minute DIY job costs $40–80 in parts and prevents $4,000+ fuel pump failures.
Where is a secondary fuel filter located?
The secondary filter is located right before the fuel injectors because it's incredibly important that the fuel entering the injectors is as clean as possible.
Where are the fuel filters on a Ram 3500?
But that hose is typically not very long. So you can either try to reach up under there with a container to catch the fuel or you could try to connect a small hose extension to that drain hose.
Does a 6.7 Cummins have two fuel filters?
6.7 Cummins Explained. Quick Answer: Most Cummins trucks use one fuel filter, but 2013-2026 Ram 6.7L Cummins trucks use two fuel filters - a rear water separator and a front final fuel filter. Both must be replaced together to properly protect injectors and the high-pressure fuel system.