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Service bulletin M1640

A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.

The communication, as NHTSA indexes it (as of 2026-10-19)
TypeService bulletin
NHTSA id11016837
Published by NHTSA2025-04-08
Manufacturer's numberM1640
Manufacturer's date2025-03-15
NHTSA componentUNKNOWN OR OTHER; ENGINE

NHTSA's summary

SERVICE BULLETIN M1640 (REV A): COOLING SYSTEM ENHANCEMENT FOR 2024 CENTER COOLED TOURING MODELS TOURING MODELS. PURPOSE: Revision (A). Updated: Part Numbers, Part No. 62800073 is obsolete. This bulletin inform dealers that starting on April 30, 2024, all Center-Cooled touring vehicles will be assembled with new components, engineered to help improve a service bleed of the cooling system. • Before March 12, 2024 all vehicles were built with the early system. • From March 12, 2024 to April 30, 2024 vehicles were built with early and late system designs. • After April 30, 2024 all vehicles were built with the late design. The components used in Early Models are listed in Table 2. The components used in Later Models are listed in Table 3. These parts will be listed separately in the parts catalog labeled as Early and Later models with an applicable date noted. Do not mix the components used in Early and Later Models. They are not interchangeable. Should Early Model components become unavailable in the future, see the Parts Catalog and Parts Price File for supersession information.

The document

The document is the manufacturer's. This site does not hold it. NHTSA files a document at one of these two addresses; we have not asked NHTSA which.

Components

Engine

Vehicles listed
HARLEY-DAVIDSON FLHX2024
HARLEY-DAVIDSON FLHXSE2024
HARLEY-DAVIDSON FLTRX2024
HARLEY-DAVIDSON FLTRXSE2024
HARLEY-DAVIDSON FLTRXSTSE2024

Listing a model year does not mean every vehicle of it is concerned: the document says which.