Product Description
MAHLE S42221.020 is a premium +.020” over piston ring set for the 1989–2002 5.9L Cummins (12-valve & 24-valve). It’s an OE-quality, single-cylinder ring pack—order quantity 6 for all six pistons.
- Application: 5.9L Cummins B-Series (6BT/ISB) 1989–2002
- Size: +0.020" over (4.036" / ~102.6 mm bore)
- Construction (typical for S42221 family): Top ring ductile iron with ceramic-chrome facing; second ring cast iron; oil ring cast iron, 3-piece (ref. MAHLE/Clevite data)
- GTIN/UPC: 027067928801
Fitment
- 1989–1998 Dodge Ram 2500/3500, 5.9L Cummins 12-valve (6BT)
- 1998.5–2002 Dodge Ram 2500/3500, 5.9L Cummins 24-valve (ISB)
Cross Reference Numbers
- MAHLE/Clevite: S42221.020 (family: S42221)
- Cummins (related ring sets seen in industry catalogs): 3802050, 4429051, 4638644 (verify sizing before purchase)
What’s Included
Complete piston ring pack for one cylinder at +.020" oversize.
FAQ
Will this fit my 1989–2002 5.9L Cummins?
Yes—this +.020" set fits overbored 5.9L Cummins engines across 12V (1989–1998) and 24V (1998.5–2002). Always confirm bore size during your build.
How many sets do I need for a full engine?
You need six sets—one ring pack per piston.
What are the ring materials?
Top ring is typically ductile iron with ceramic-chrome facing for wear resistance; second and oil rings are cast iron.
Does this include pistons?
No—rings only. Order pistons, bearings, and gaskets separately.
Any installation tips?
File-fit as required; check end gaps to spec for your target power/EGT. Stagger ring gaps, verify cylinder finish (RA), and lubricate during assembly.
