1994 Ford F-350 transmission problems

An engineering analysis closing report is included.

EA95012

Ford has acknowledged a serious problem with the accessory drive belt system (serpentine belt) in the subject vehicles.several service bulletins have been issued to address concerns related to belt tracking or wear.ford maintains that the subject condition does not present an unreasonable risk to highway safety, arguing that the low incidence of failures alleging safety consequences (I.e., fires, fluid leaks, and/or accidents) is strong evidence in support of this claim.ford has indicated receipt of 4,445 field reports and 46891 warranty claims concerning the subject condition. Ford maintains that the low number of reported hose ruptures and/or fires, relative to total belt failures, shows that the problem is a durability concern that presents very little risk to motor vehicle safety.ford intends to address the problemin a service bulletin scheduled for publication the week of march 13, 1995.odi has received several claims alleging that incidents of belt failure are causing collateral damage to adjacent fluid systems (e.g., power steering hose, coolant hose, and automatic transmission oil cooler hose).release of these fluids within the engine compartment may result in a vehicle fire, if exposed to a sufficiently hot surface area.the autoignition temperature for transmission oil may be as low as 300 c (570 f), while power steering fluid and engine coolant are generally harder to ignite (closer to 500 degree c (900 degreef)).damage to battery cable insulation has also been alleged as a consequence of serpentine belt failure.odi has received four reports alleging failure of adjacent fluid system hoses from contact with a broken serpentine belt.one report involved an econoline rv cutaway chassis with a 7.3l v-8 navistar engine, used in the transport of disabled children.an engine compartment fire destroyed the vehicle in november 1994.the fire is alleged to have been caused when the serpentine belt broke at highway speed and ruptured a transmission coller line. The report alleges finding belt fragments and traces of transmission fluid up the road from the fire scene, near where the driver had heard a pop just prior to the fire.the driver reportedly sustained minor burn injuries while evacuating passengers.owner reports also allege some loss of vehicle control occurs with the belt failures, due to the loss of power assist capability to the braking and steering systems.the serpentine belt drives the power steering pump and the vacuum pump for the brake booster in the subject vehicles.as stated in ford bulletin 93-23-27: some diesel powered vehicles are experiencing drive belt tracking concerns.this is caused by front end accessory drive (fead) misalignment, which may result in the belt coming off the accessory drive pulleys.if this occurs, several warning lights will illuminate and the vehicle will lose alternator and A/C function and water pump circulation.in addition, steering efforts will increase and, after one or a few brake applications, brake efforts wil progressively increase. There are three odi complaints and five ford complaints, not included in the failure report summary of this resume, alleging that the reductionin vehicle control associated with acessory drive belt failure resulted in an accident.this investigation is being upgraded to further analyze the potential safety consequences of serpentine belt failure in the subject vehicles.

PE94087