Product Description
MAHLE 41909.04 is a complete +.040" oversize piston ring set for the 2001–2004 GM 6.6L Duramax (LB7). Built to OE standards and pre-lapped for fast seating, it’s sold as a full engine set and includes top, second, and oil ring assemblies for every cylinder.
- Oversize: +0.040" (1.02 mm)
- Bore (nominal): 4.0945"
- Top ring: ductile iron, plasma-moly face
- Second ring: cast iron
- Oil ring assembly: GNS
- Sold as a complete engine set
- MPN: 41909040 • GTIN/UPC: 027067460820
Fitment
- 2001, 2002, 2003, 2004 Chevrolet/GMC 6.6L Duramax LB7 (Silverado/Sierra 2500/3500 and related LB7 platforms)
Cross Reference / Related Sizes
- MAHLE/Clevite family: 41909 (STD), 41909.01 (+.010), 41909.02 (+.020), 41909.03 (+.030), 41909.04 (+.040)
- Alternate formatting: 41909.040, 41909040
- GTIN/UPC: 027067460820
What’s Included
- Complete ring set for all eight cylinders: top, second, and oil ring assemblies matched to +.040" overbore
FAQ
Will this fit my 2001–2004 LB7?
Yes—this +.040" set is listed for the 2001–2004 6.6L Duramax LB7. Always confirm your required oversize before ordering.
Is this a full engine set or one cylinder?
It’s a complete engine set (rings for all eight cylinders).
Do these rings require an extended break-in?
They’re pre-lapped to seat quickly, so no special break-in is typically required beyond standard best practices.
What materials/coatings are used?
Top ring is ductile iron with a plasma-moly face; second ring is cast iron; oil ring is a GNS assembly—engineered for durability and oil-control.
Any installation tips?
Measure every cylinder, verify overbore (+.040"), check end gaps and orientation, and follow your machine shop’s hone finish (RA) specs for best sealing.
