2004.5-2005 Chevy Duramax LLY Air Filters

Air filters on the 2004.5-2005 Chevrolet LLY

The filter sits in the fender-mounted airbox ahead of the resonator, the intake tube and the turbo inlet manifold. Everything the Garrett GT3788VA compressor pulls, and it is a 62 mm wheel, the largest on any factory Duramax, has to come through that element first. Because the factory mouthpiece already necks down and raises restriction, the LLY has less margin for a plugged filter than most trucks. Whatever restriction the filter adds stacks on top of a restriction the engine already has.

What fails and why

Filters do not fail so much as fill up. A restricted element mimics turbo trouble on the LLY: slow spool, high EGT, a soft feel under load. BD Diesel's first check for what owners call sticking vanes is boost leaks and intake or filter restriction, not the turbo. On a Silverado that lives on Florida sand roads or a farm, the element loads faster than any mileage interval predicts. The other thing that fouls the intake is internal: EGR soot and PCV oil vapor coat the tract downstream of the filter, which no element can prevent, so do not blame the filter for a dirty Y-bridge.

Stock replacement vs. upgrade

If you are running the factory airbox, a 2001-2005 Duramax drop-in element is the replacement. If you have an S&B or Banks intake kit, use the element made for that kit; the S&B KF-series and the Banks 42138 are replacement filters for their own systems, not for the stock box. Oiled cotton elements can be cleaned and re-oiled with a kit; dry elements like the Wehrli 4-inch inlet filter skip the oil and are rinsed instead. A pre-filter wrap is the real upgrade for a dusty truck: it keeps the element open longer between services. Cold air intakes are named for the LLY (S&B and AFE) with a cited 25-35 percent airflow improvement, but the filter alone is not where that gain comes from.

What we carry

S&B has three: the KF-1008 replacement filter for 2001-2005 Duramax, the KF-1035 that also crosses to the 1994-2007 5.9L Cummins, and the WF-1023 filter wrap for 2001-2010 Duramax elements. Banks Power has the 42138 air filter element and the 42643 pre-filter wrap made for it. Wehrli Custom Fabrication offers the WCF100717 4-inch inlet dry filter that cross-lists to 2001-2024 Duramax, 2003-2018 Cummins and the 2003-2007 6.0L Power Stroke. PPE has the 115000105 element air filter for 2001-2005 Duramax, and Mahle the LX2562 air filter for the same years.

Fitment notes

Filters fit the intake, not the truck, so the first question is whether your Silverado still has the factory airbox or an aftermarket kit, and which brand. The product pages list which system each element serves; the fitment checker will not catch a stock-box filter ordered for an S&B tube. Cross-listing to Cummins and Power Stroke years on a universal element is normal and not a mistake. Intake filters are identical across 2500HD and 3500, SRW or DRW, 2WD or 4WD, and all cab and bed combinations.

Frequently asked questions

How often should I change the air filter on an LLY Silverado?

More often than the book if the truck sees dirt. A restricted filter on this engine produces turbo-like symptoms, so inspect it regularly and replace or clean it when it is visibly loaded. Trucks on sand roads or job sites should run a pre-filter wrap.

Will the S&B KF-1008 fit my stock airbox?

No. The KF-series filters are replacement elements for S&B intake kits. For the factory airbox, look at the Mahle LX2562 or the PPE 115000105, both listed for 2001-2005 Duramax, and confirm on the product page.

Oiled or dry filter for a truck that tows in Florida heat?

Either works if it is clean. An oiled cotton element can be washed and re-oiled; a dry element such as the Wehrli 4-inch inlet filter is rinsed and reused without oil. What matters on an LLY is that the element is not restricting the compressor, so pick the type you will actually service and add a wrap if the truck sees dust.

Not sure what fits? Call the shop at the number in the header, or use the fitment checker on any product page. We install everything we sell.