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Cummins · Hardware & Fasteners
3949708CUM
In stock · ships from Knoxville
This is a genuine Cummins O-ring seal designed to create a tight, leak-proof seal in engine fluid or air passages.
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Verified fitment for 3 applications
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All confirmed applications for this part number.
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Used in various heavy-duty trucks, buses, and equipment powered by these Cummins engines. Verify exact location in your engine's parts diagram before ordering.
Part data verified against 5 catalog sources
Numbers this part supersedes or interchanges with. Showing 3 of 3.
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It is commonly used in Cummins ISB, ISF, and QSB diesel engines, where it sits between mating surfaces to prevent oil, coolant, or air leaks. Over time, O-rings can harden or crack from heat cycling, causing drips or performance issues, so they’re replaced during routine maintenance or when a leak is suspected. A properly sealed engine maintains pressure and lubrication, protecting internal components and extending engine life.
Part Number: 3949708CUM
O RING
Vendor: MHC Kenworth
Dealer: KP Services Crossville
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