Typically a 27 mm socket fits the primary fuel filter cap on the Ford 6.7 Power Stroke.
Understanding the fuel filter system on the 6.7 Power Stroke
The 6.7L Power Stroke uses a two-stage fuel filtration system with a primary filter and a water separator housed together on the engine. The cap you unscrew to replace the filters can require a large socket, and some configurations use a dedicated fuel filter wrench. Because sizes can vary by year and filter kit, it’s important to confirm the exact tool size for your specific truck before you start.
Typical tool requirements
Before listing the tools, here is what you’re most likely to need for the cap and related hardware.
- 27 mm socket for the primary fuel filter cap
- 30–32 mm socket or a Ford-specific fuel filter wrench for the water separator cap (if your configuration uses a separate cap)
- Long-handled ratchet or breaker bar for extra leverage
- Diesel-safe gloves, rags, and a drain pan for spills
Having the right tools helps prevent stripping the cap and makes the job cleaner and safer.
Step-by-step guide to changing the fuel filter
Follow these steps to change the fuel filter safely and effectively. The outlined process is typical, but always refer to your owner’s manual or service bulletin for year-specific torque specs and priming procedures.
- Relieve fuel-system pressure. Open the fuel cap to relieve any built-up pressure, then follow Ford’s procedure to purge the system (often involving cycling the ignition a few times without starting).
- Turn off the engine and disconnect the negative battery cable to prevent accidental cranking.
- Place a drain pan under the filter housing to capture fuel drips.
- Using the 27 mm socket, carefully loosen and remove the primary filter cap. Remove the old filter cartridge and inspect the cap o-ring for damage.
- Install a new filter cartridge and replace the o-ring if needed. Lightly lubricate the o-ring with clean diesel fuel or the product manufacturer's recommended lubricant.
- Reinstall the cap and snug it by hand, then tighten to the service-spec torque. If your manual provides a torque value, use it; otherwise tighten firmly without overtightening.
- Prime the fuel system according to Ford’s procedure (often by cycling the key to RUN a few times to build pressure) and start the engine. Check for leaks around the cap and fittings, and re-tighten as necessary.
After priming, run the engine and inspect for leaks. If you notice any fuel seepage, stop and reseat or replace seals as needed.
Safety considerations and tips
Diesel fuel is flammable and under pressure, so work in a well-ventilated area away from open flames. Wear gloves, dispose of rags appropriately, and keep fuel away from ignition sources. If you’re unsure about the exact cap size for your year/model, consult the official Ford service manual or a dealership service department before proceeding.
Summary
For most Ford 6.7 Power Stroke vehicles, you’ll use a 27 mm socket to remove the primary fuel filter cap. Some configurations or water separator caps may require a larger size or a dedicated filter wrench. Always verify the exact size for your year and filter kit, follow the manual for torque specs, and prime the system after installation to ensure proper operation and prevent air leaks. A careful approach with the right tools will keep your fuel system clean and functional.
What size wrench for fuel filter?
Fuel Filter Housing Wrench Sizes
The most common sizes found in truck filter wrench size guide charts range between 27 mm and 36 mm, depending on the engine brand and model.
What size is the fuel filter on a 6.7 powerstroke?
Outer Diameter: 3.31 Inches (84 MM) Thread Size: 3/4-16. Length: 3.94 Inches (100 MM)
What size socket is the fuel filter on a 6.7 Ford?
28MM LOW PROFILE SOCKET ('10-'26, 2500/3500 6.7L & '20-'23, 1500 3.0L, SEE DESCRIPTION FOR SPECIFIC APPLICATIONS)
Which company's fuel filter is best?
What Are The Top 5 Best Fuel Filter Brands Recommended By Experts...
- Bosch. Bosch has long been regarded as a hallmark of precision engineering in the automotive parts world, and their fuel filters reflect that reputation.
- Mahle.
- Fram.
- Mann-Filter.
- ACDelco.