1977 MACK DMM Recalls (5)

Campaign:
79V133000 on 10/11/1979
Component:
Engine and engine cooling:engine
Manufactured:
01/31/1977 - 02/28/1979
Affected:
23,000
Defect:
In the event of turbocharger compressor wheel failure, one or more of the four capscrews that hold the turbocharger together may be struck by parts of the compressor wheel, resulting in the capscrews being damaged. if these capscrews are damaged to the point that they allow the compressor back plate to dislocate from the turbocharger bearing housing, engine lubricating oil may be allowed to escape under pressure, contacting the engine exhaust manifold sections or turbocharger turbine housing.
Correction:
Dealer will install a shield for the heads of the four capscrews, along with stronger sae 8 grade 8 capscrews, if necessary, at no cost to owner.
Notes:
Vehicle description: trucks equipped with endt (b) 676, etaz (b) 673a, and etay(b) 673a engines.system: engine and engine cooling.consequences of defect: engine lubricating oil, in the presence of a source ofignition, could lead to an engine compartment fire and serious injury tovehicle passengers.

Campaign:
78V210000 on 10/11/1979
Component:
Service brakes, air:antilock:interconnecting assembly(wiring)
Manufactured:
09/30/1977 - 08/31/1978
Affected:
19,370
Defect:
Delays of up to about 2 seconds may exist in the brake application times to the brakes on the bogie axles in the presence of certain types of wheel speed sensor signal discontinuities or distortions that may occur as a result of sensor wire failure. this constitutes a non-compliance to federal motor vehicle safety standard no. 121, "air brake systems".
Correction:
Dealer will install new wheel speed sensors that incorporate improved wiring and the present bogie anti-wheel lock system will be changed to an axle-to-axle system for improved reliability.
Notes:
Vehicle description: heavy trucks.system: service brakes; electrical wiring and connectors.consequences of defect: this delay in effective braking action could lead to anaccident under certain traffic conditions.

Campaign:
78V172000 on 10/11/1979
Component:
Steering:linkages:knuckle:spindle:arm
Affected:
13,800
Defect:
The existing cross steering arms may have insufficient fatigue life in the neck area. this is near the boss for the cross steering tube ball joint connection. failure of either of the cross steering levers could lead to loss of steering control of the right front wheel.
Correction:
The dealer will inspect and, if necessary, install cross steering arms of improved design and greater strength.
Notes:
Vehicle description: truck tractors.system: steering; steering arm.consequences of defect: loss of steering control could lead to loss of vehiclecontrol and an accident.

Campaign:
77V173000 on 10/11/1979
Component:
Engine and engine cooling:cooling system:fan
Affected:
48,000
Defect:
The flex blade fans on the involved vehicles may develop cracks in the laminated stiffener as a result of fatigue during operation. if such a condition exists and the cracks go undetected, continued operation could cause pieces of the stiffener to break off.
Correction:
Dealer will replace the original fan with a steel fixed blade fan, free of charge.
Notes:
Vehicle description: trucks equipped with six-cylinder engines.system: engine cooling; fan.consequences of defect: broken pieces can be propelled outside of the fanshroud and will present an immediate danger and possible injury to personsstanding nearby.note: prior to correction, vehicle should not be serviced with the hood raisedand the engine running.

Campaign:
77V174000 on 10/11/1979
Component:
Seat belts:front:anchorage
Affected:
6,591
Defect:
The involved vehicles do not conform to federal motor vehicle safety standard no. 209, "seatbelt assemblies". although the seatbelts in question performed marginally with respect to the 5000 lb. load requirement, additional testing confirmed that the anchor could fail, allowing either the anchor to slip over the hold-down nut or the anchor to separate into two pieces.
Correction:
Dealer will inspect and, if necessary, replace seat belt assemblies without charge to owner.
Notes:
Vehicle description: trucks.system: interior; seat belt anchorage assembly.consequences of defect: in the event of an accident, these seat belts may notadequately restrain passengers and serious injuries may result.

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