Mazda B-Series Truck 1994–1997 — technical service bulletin
Bulletin 97122800197 · NHTSA communication 54134 · issued Dec 28, 1997
Technical service bulletin
communication type
Engine and Engine Cooling
component
1994–1997
model years
5
vehicle entries
Official summary
Vehicles may experience a thump noise from the heater core that may be accompanied by excessive temperature gauge fluctuation. *yc
Vehicles covered
What a TSB means. Technical service bulletins are repair guidance manufacturers send to dealers — they are not recalls, and repairs are not automatically free (warranty extensions are an exception worth checking). The full document is available via NHTSA’s vehicle lookup.