Crankcase Ventilation Filter: When to Replace + Symptoms

What the CCV Filter Actually Does

Every running engine builds up pressure in the crankcase from combustion gases that slip past the piston rings (blow-by). On older diesels, that pressure vented through an open tube to atmosphere. Emissions rules since 2007 require closed crankcase ventilation, so manufacturers added a filter that traps the oil mist carried in those blow-by gases and returns clean air to the intake. Cummins calls it CCV (Crankcase Ventilation), Ford calls it CCV on 6.7 Power Stroke, GM calls it the CDR (Crankcase Depression Regulator) on Duramax. They all do the same job: filter oil droplets out of blow-by air before it goes back into the intake tract. A clean CCV filter produces minimal back pressure in the crankcase and lets the engine breathe normally.

Replacement Interval and Why It Matters

Cummins recommends CCV filter replacement every 67,500 miles on the 6.7L ISB -- the factory service manual lists this in the L0/L1/L2 maintenance schedule. Ford recommends the 6.7 Power Stroke CCV at 67,500 miles under the normal schedule and 45,000 miles under severe duty. GM lists no specific interval on the CDR but most Duramax service shops recommend inspection at 100,000 miles. Running past the interval means the filter element is saturated with oil, air cannot pass freely, and crankcase pressure rises. When crankcase pressure exceeds what the front and rear main seals can hold, oil pushes out. The progression is: slight oil at the vent tube (normal), oil-soaked intake tract, front crank seal seep, rear main leak, turbo compressor seal failure. By the time symptoms appear at the turbo, the CCV filter is typically 2-3 service intervals overdue.

Symptoms of a Clogged CCV Filter

Early: mild oil consumption bump (0.5 quart per 3000 miles becomes 1 quart per 3000). Noticeable blow-by at the oil fill cap with engine running -- remove the cap and air should lift a piece of paper off the opening but not blast it off; strong pulsing means crankcase pressure is high. Oil film on the underside of the air intake tube between turbo and CCV filter. Oil pooling in the turbo intake boot. Advanced: oil leaking from the front timing cover seal, rear main seal, oil pan gasket, or turbo compressor seal (which dumps oil into the intercooler and drives up DEF usage as the engine burns oil through combustion). Trucks with heavy blow-by often show elevated exhaust back pressure and can even throw P2455/P2456 style codes on some applications because oil contaminates the DPF pressure sensor.

6.7L Cummins CCV Replacement Walkthrough

On 2007.5-2018 Cummins 6.7L, the CCV filter housing sits on top of the valve cover and looks like a black plastic cylinder with two clips holding the cap down. Part number Cummins 5802794 or Fleetguard CV52001. Remove the two cap clips, lift the cap, pull the filter element straight up. Inspect the housing for standing oil -- more than a thin film means the filter was overdue or the drain passage is blocked. Install the new element making sure the rubber O-ring seats properly. Seat the cap and reattach the clips. Check the drain tube at the front of the valve cover -- it should be clear and angled downward to let collected oil return to the pan. On 2019+ 6.7L ISB applications with Gen 3 engines, the CCV housing is integrated into the valve cover and the element is slightly different (Fleetguard CV52014).

6.7L Power Stroke CCV Replacement Walkthrough

On the 2011+ 6.7L Power Stroke, the CCV filter is located on the passenger-side valve cover under a plastic shroud. Motorcraft part BC3Z-6A785-A. Remove the shroud (two 10mm bolts and a couple of clips), disconnect the CCV heater connector (a small 2-pin plug) to prevent damage, remove the four small bolts or clips retaining the cover, and lift off the cap. Pull the saturated filter straight up. Install the new filter with the arrows facing the correct direction (up on most applications). Reattach the cover, reconnect the heater, and reinstall the shroud. Ford added an internal heater to prevent CCV freezing in cold weather -- if that heater fails, you can get moisture accumulation and a secondary restriction, so inspect it during replacement.

Common Mistakes and What to Avoid

Do not clean and reuse a CCV filter element -- the media is specifically designed to trap sub-micron oil droplets and washing it destroys that capability. Do not delete the CCV filter or run an open breather on a 2007+ truck -- it is a federal emissions violation and will cause oil fogging at the intake that triggers DPF contamination. Do not install aftermarket 'high-flow' CCV filters from no-name brands -- they often pass more oil than they trap. Stick with Fleetguard, Donaldson, or Motorcraft OEM-equivalent elements. Watch for oil-saturated intake tubes downstream of the CCV -- if the tube is wet inside, the filter was clogged long enough to push oil past it, and the turbo intake and intercooler need cleaning too. Finally, if the truck has been running a clogged CCV for more than 30,000 miles, budget for a compression test -- excessive crankcase pressure accelerates ring wear.

Frequently Asked Questions