Vehicle recall 78V170000 · August 8, 1978

Mack RWL, RWS and 2 more models

The possibility exists that the aluminum engine rear support brackets may fail due to metal fatigue.

Source: NHTSA data as of September 22, 2026. Last refreshed Sep 23, 2026, 2:43 AM UTC.

Summary: The possibility exists that the aluminum engine rear support brackets may fail due to metal fatigue. This type of failure would allow the engine and transmission assembly to dislocate downward. This will result in throttle control loss with the engine operating continuously in the mid to upper range of the governed speed range.
Remedy: Dealer will inspect and, if necessary, replace aluminum support brackets with brackets made from ductile iron for increased strength.
Notes: Vehicle description: trucks.system: engine; engine mounting bracket.consequences of defect: loss of throttle control may result in loss of vehiclecontrol and an accident.

Recall details

NHTSA campaign: 78V170000
Reported to NHTSA: August 8, 1978
Filed by: MACK TRUCKS, INCORPORATED
Owner notification: December 4, 1978
Vehicles potentially affected: 850
Initiated by: the manufacturer
Components: Engine and engine cooling › Engine

Recall 78V170000 on nhtsa.gov, with the manufacturer’s documents

Vehicles covered

As listed by NHTSA. A recall usually covers only some vehicles of each model and year, often a production date range.

Mack RWL (1975-1978): 1978, 1977, 1976, 1975
Mack RWS (1975-1978): 1978, 1977, 1976, 1975
Mack WL (1975-1978): 1978, 1977, 1976, 1975
Mack WS (1975-1978): 1978, 1977, 1976, 1975

Has your Mack been repaired?

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