CUMMINS 5271251 OEM CYLINDER HEAD GASKET (+.020 THICKNESS) – ISB/QSB 6.7L (2007.5–2018 RAM; ESN VERIFY)

Product Description

CUMMINS 5271251 OEM CYLINDER HEAD GASKET (+.020 THICKNESS) – ISB/QSB 6.7L (2007.5–2018 RAM; ESN VERIFY) is the genuine +.020" service head gasket for ISB/QSB 6.7L Cummins platforms. When machining, piston protrusion, or ESN data calls for an oversize gasket, 5271251 restores proper quench, compression, and long-term sealing on hard-worked 6.7L Ram trucks and industrial QSB/ISB engines.

This multi-layer steel (MLS) Cummins cylinder head gasket is engineered to OE spec for clamp-load stability, clean coolant and oil passages, and reliable sealing under high cylinder pressures. It is the correct choice when a standard-thickness gasket is no longer within spec due to decking or block/head machining – helping you avoid repeat tear-downs and protecting your investment in machine work, studs, and tuning.

Fitment – Automotive & Industrial

• Automotive (On-Highway): 2007.5–2018 Ram 2500/3500, 6.7L ISB (24-valve common-rail diesel) – when +.020" service thickness is specified by Cummins or your machine shop (verify by VIN/ESN and piston protrusion).
• Industrial / Off-Highway: QSB6.7 / ISB6.7 engines, including certain Tier-rated QSB6.7 M CM2250 and related variants – always confirm by ESN and Cummins service data before ordering.

Thickness note: CUMMINS 5271251 is a +.020" service gasket. It is NOT a direct substitute for standard-thickness gaskets. Always measure piston protrusion and follow Cummins published specs before choosing gasket thickness.

Why Use a Genuine Cummins +.020" Gasket?

• Restores proper piston-to-head clearance after surfacing the block and/or cylinder head.
• OE MLS construction for stable clamp load and sealing on high-cylinder-pressure 6.7L applications.
• Correct coolant/oil passage geometry to protect against internal leaks and hot spots.
• Direct-fit for ISB/QSB 6.7L platforms when +.020" is specified – no guesswork on aftermarket thickness codes.

Cross-Reference & Related Cummins Parts (CPP DIESEL)

• CUMMINS 4955354 OEM UPPER ENGINE GASKET KIT – ISB 6.7L (2007.5–2018) STANDARD THICKNESS – complete upper-engine reseal kit using the standard head gasket for non-machined engines.
• CUMMINS 3927063 OEM CYLINDER HEAD BOLT – ISB 5.9L/6.7L (1998.5–2018) – OE head bolts; 26 required per engine for 6.7L ISB.
• CUMMINS 4890833 OEM REAR MAIN CRANKSHAFT OIL SEAL – RAM 6.7L (2007.5–2018) / SELECT 5.9L BY ESN – ideal to replace while the drivetrain is apart for top-end work.
• CUMMINS 5297640 OEM FUEL RAIL PRESSURE SENSOR – 6.7L CUMMINS (2007.5–2012) | ISB/QSB – frequently serviced alongside top-end and injector work.
• CUMMINS 3978517 OEM CYLINDER HEAD GASKET (.020 MARINE) – RAM 5.9L ISB (2003–2007) | QSB5.9 – +.020" service gasket option for 5.9L ISB/QSB applications.

Installation Notes

• Measure piston protrusion at multiple cylinders and compare to Cummins spec to confirm +.020" gasket selection.
• Inspect and clean block deck and head surface; verify flatness and surface finish after machining.
• Follow Cummins torque and angle procedures with lubricated fasteners as specified in the service manual.
• Use new head bolts or approved studs and retorque only if service information calls for it.
• Change engine oil, filter, and coolant after reassembly and initial heat cycles.

What’s Included

• (1) Genuine CUMMINS 5271251 multi-layer steel cylinder head gasket (+.020" service thickness)

FAQ

WILL THIS FIT MY 6.7L CUMMINS RAM?

Yes – CUMMINS 5271251 is used on most 2007.5–2018 6.7L ISB Ram 2500/3500 applications that require a +.020" service head gasket. You must confirm fitment by VIN/ESN and piston protrusion or Cummins gasket-thickness chart before ordering.

WHAT DOES “+.020" THICKNESS” MEAN?

“+.020"” indicates this gasket is approximately 0.020" thicker than the standard gasket. It is selected when block and/or head machining, or piston protrusion measurements, call for an oversize gasket to maintain safe piston-to-head clearance and compression ratio.

CAN I USE THIS IN PLACE OF A STANDARD-THICKNESS GASKET?

No. Using a +.020" gasket on an engine that does not require it can lower compression and affect performance. Likewise, using a standard-thickness gasket where a +.020" is specified can reduce clearance and risk piston-to-head contact. Always follow Cummins spec and ESN data.

IS THIS A GENUINE CUMMINS PART OR AFTERMARKET?

This is a genuine Cummins OEM cylinder head gasket, supplied through authorized distribution – not a private-label or white-box aftermarket part.

WHAT OTHER PARTS SHOULD I REPLACE WITH THIS GASKET?

Most top-end jobs should also include an upper engine gasket set (seals, intake/exhaust gaskets, injector seals), new head bolts or studs, fresh coolant, and an oil/filter change. See the related Cummins parts above for commonly paired components.

DOES THIS PART CARRY A CALIFORNIA PROP 65 WARNING?

Yes. This gasket and its packaging may contain materials known to the State of California to cause cancer and birth defects or other reproductive harm. For more information, visit www.P65Warnings.ca.gov.

Specifications for cummins 5271251