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Denial of Motor Vehicle Defect Petition, DP00-008

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National Highway Traffic Safety Administration (NHTSA), Department of Transportation.


Denial of petition for a defect investigation.


This notice sets forth the reasons for the denial of a petition submitted to NHTSA under 49 U.S.C. 30162, requesting that the agency commence an investigation into an alleged defect in the water pump in model year (MY) 1994-1998 Saab 900S motor vehicles.

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Ms. Jennifer Russert, Office of Defects Investigation (ODI), NHTSA, 400 Seventh Street SW., Washington, DC 20590. Telephone: (202) 366-1869.

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On September 18, 2000, Mr. Avery B. Goodman submitted a petition requesting NHTSA to open an investigation into an alleged defect in MY 1994-1998 Saab 900S vehicles. In April 1997, Saab Automotive AB (Saab) had issued Customer Satisfaction Campaign 10445, which referred to the replacement of the water pumps in MY 1994-1996 Saab 900 vehicles with four-cylinder engines. Saab stated that load variations in the belt circuit could cause the water pump pulley to crack at the hub center, subsequently causing the drive belt to jump off the pulley. In the event of a failure, there would be a loss of belt tension, causing loss of power steering, as well as other belt driven functions. The petitioner alleged a safety-related defect in his MY 1994 Saab 900, stating that the water pump pulley broke off at the weld to the pulley shaft. The petitioner was concerned that the water pump pulley failure resulted in the loss of power steering, air conditioning, and engine cooling systems.

The MY 1994 Saab 900 was a new vehicle design (with the exception of the convertible, which carried over the previous generation design until the 1995 model year). Engine positioning was changed, and a new accessory drive design was implemented. The new drive design featured a water pump with the drive belt pulley welded onto the pump shaft. In December 1994, Saab became aware of problems with cracking of the water pump pulley and subsequent loss of drive power to the air conditioning compressor, alternator, and power steering pump through warranty claim data.

Upon analysis, Saab discovered weld fatigue cracks at the water pump/pulley junction. Saab determined that the root cause was the center of the drive belt not being aligned with the center of the water pump pulley attachment. This induced rotational bending of the pulley at the weld joint to the water pump shaft, in line with applied drive belt load. Continual bending as the pulley rotated under normal engine drive conditions subsequently caused fatigue cracks in the weld.

Cracking of the water pump pulley center hub can result in the pulley separating from the water pump shaft, causing the drive belt to jump off of the pulley, and subsequently cause loss of drive belt tension. Loss of belt tension would cause a loss of power drive to the following components: Air conditioning compressor, engine water coolant pump, alternator, and power steering pump

Testing of a bolted pulley demonstrated the added strength of the bolted pulley design and no signs or potential for fatigue cracking. The bolted pulley design was implemented into vehicle production early in MY 1996 and Saab subsequently decided to implement Customer Satisfaction Campaign 10445 worldwide. Under that campaign, dealers were to inspect the water pump belt pulley. If there was no yellow identification mark, indicating that a newly designed water pump had been installed, and the pulley was not attached to the pump by bolts, dealers were to replace the pump.

There have been 4 complaints (including that of the petitioner) to NHTSA of problems with the power steering assist, water pump, water pump pulley, or similar concerns on MY 1994-1996 Saab 900 vehicles. One occurred on a new MY 1995 vehicle, the other three, including the petitioner's, occurred on MY 1994 vehicles in 1999. Saab reported an additional 5 complaints (Saab had a total of 8 complaints, but 3 duplicated ODI complaints) of similar water pump pulley failures on MY 1994-1996 vehicles since the initiation of Campaign 10445. There have been no reports of problems with the power steering assist, water pump, water pump pulley, or similar concerns on MY 1996, 1997 and 1998 Saab 900 vehicles.

If the pulley fails, engine cooling, power steering assist, generator charging ability, and the air conditioning would all fail. The petitioner expressed concern with the loss of power steering and alleged he had difficulty controlling his vehicle on the freeway. Although he did not mention his speed, he said he was slowing and attempting to exit the freeway. In a study conducted by Saab in October 1993, unrelated to this petition, loss of power steering assistance was analyzed to determine what effect it could have on a driver's ability to maintain steering control. Saab concluded that without the variable power assist, subject vehicles could be controlled safely at highway speeds. The agency's experience supports Saab's conclusion that vehicles can be controlled at highway speeds despite a loss of power steering. With a loss of power steering at low speeds, it is still possible to complete a turn or a parking maneuver, although it typically takes more effort on the part of the driver to turn the steering wheel. While slowly Start Printed Page 56146turning a corner, or parking, loss of power steering does not pose a significant risk to traffic safety. The loss of drive to the generator prevents the vehicle's battery from being charged, but is a progressive loss of battery power and does not represent a safety concern. Loss of engine cooling could cause the vehicle to overheat, typically resulting in coolant overflow at the radiator or a burst cooling system hose, however, there have been no reports of such incidences. Air conditioning is an auxiliary function, the loss of which does not affect the safe operation of the vehicle.

In view of the foregoing, it is unlikely that NHTSA would issue an order for the notification and remedy of the alleged safety-related defect as defined by the petitioner in the subject vehicles at the conclusion of the investigation requested in the petition. Therefore, in view of the need to allocate and prioritize NHTSA's limited resources to best accomplish the agency's safety mission, the petition is denied.

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Authority: 49 U.S.C. 30162(d); delegations of authority at CFR 1.50 and 501.8.

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Issued on: November 1, 2001.

Kathleen C. DeMeter,

Director, Office of Defects Investigation, Safety Assurance.

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[FR Doc. 01-27869 Filed 11-5-01; 8:45 am]