Detroit Diesel Marine Heat Exchanger Expansion Tank for 12V-71 - Used

Application: Detroit Diesel 12V-71 series marine engine — cast-iron heat exchanger / coolant expansion tank assembly with Detroit Diesel logo cast into the top cover, integral raw-water side tube housing, and top expansion/fill neck. Commonly referenced as OEM 5117713; may also fit other 71-series marine builds. Condition: Used take-off, sold as a housing / core-shell assembly. Heavy exterior paint loss and surface rust consistent with age and marine service; original green paint remains in patches. Top access cover and fasteners present. Internal tube bundle condition not verified — recommend re-core and pressure test before return to service. Any residual coolant will be drained and open ports capped before shipping. Buyer must confirm fitment by part number, photos, dimensions, engine model, serial number, and application before purchase. Used marine part sold as-is unless otherwise stated. No returns on electrical, used, special-order, or installed parts.