M939a2 Cummins 6CTA8.3 Front Crank Seal and Timing Cover Gasket p/n's


Well-known member
Livonia, MI
My stock 8.3L engine is starting to leak oil up front and the rear side of the timing case is dry, so I ordered a new replacement Cummins front crank seal and timing cover gasket. Here are the Cummins part numbers for anybody else needing to do the same. These were found from using their free Quickserve website using my engine serial number, then phoning the order in to my local Cummins service center, of which they advised of part number supersede occurrences, so these are current #'s as of this writing:

Front crank seal: 4025270 (standard replacement seal, for standard crank, no wear sleeve present, Teflon seal so install dry)
Front timing cover gasket: 3917780 (thick cardboard, use sealant)

Cummins service manual shows there to be no separate seal carrier like on the newer engines. Procedure: yank the belt, knock the crank damper/pulley off (few internal bolts), zip the timing cover off, bang the old seal out and new in, then reinstall cover using new gasket and sealant on both sides. Says to apply sealant to the OD of the new seal as well before installation into cover.

Simp, add to your Excel chart if you are staying current on it. I have not crossed them to NAPA #'s, if available.
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