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Saab 900 Pyro-TechnicsPosted 7/9/1999By Rich Cregar
Saabs are generally regarded as a "quirky" car owned by "quirky" people. This said, they also command very strong owner loyalty. This owner loyalty is a big plus for repair shops as many Saab owners will continue to spend money for maintenance and repair of their Saabs long after other people would have abandoned their Rabbits or Camrys.
Saabs are manufactured by Saab-Scania, a Swedish firm that derived from the aircraft maker, the Svenska Aeroplan Aktie Bolag -thus SAAB! Saab is currently owned by General Motors. The global economy marches on! After Word War II, the company decided to apply its engineering talents to automotive design and by 1947, had developed a prototype of a front-wheel drive, aerodynamically designed sport sedan powered by a two-cycle engine. The engine was obtained from the German car maker DKW, one of the parent companies of Audi, currently a division of Volkswagen. This design entered production in 1950 as the Model 92 and survived into the 1970s along with the two-cycle engine. In 1969, Saab introduced the Model 99, the forerunner of the 900. The 99 was modernized and enlarged in 1978 and relabeled Model 900. Featuring a longitudinal 2.0 litre, 4-cylinder engine with an integral front-wheel drive transaxle, the 900 has seen few changes. It has always been available in both turbo or non-turbo. Engines are the early 8-valve 2.0L, and later, the 16-valve twin cam 2.0L or 2.1L. Fuel systems (Bosch) are the early CIS-Lambda (K-Jetronic) and the later multi-port EFI using air mass sensing (LH-Jetronic). Since the basic platform of this car dates to the 1960s, later modifications have to be engineered as add-ons. One that you need to be aware of is the catalytic converter installed on the U.S. version of these cars. The longitudinal "tunnel" of the Saab floor pan is there to provide strength to the unitized chassis, not to accommodate anything beyond an exhaust pipe and shift linkage. Tucking a converter into this narrow space meant a close fit between the converter and the tunnel. Saab engineers solved the problem of excessive heat transfer from the converter to the floor pan by installing a metal heat shield between the converter and the floor. The shield provides a reflective surface to reflect heat back toward the ground as well as an insulating air layer between the shield and floor for further insulation.
The heat shield works ... but it rusts. And as it rusts, it loses the ability to reflect and insulate heat from the tunnel. The heat developed by the converter (over 500 degrees Fahrenheit) will penetrate a rusted heat shield and begin to heat the floor pan. Directly above the floor board is the wiring harness leading to the ignition switch, window switches, and to the rear of the vehicle. In some models this includes fuel control wiring, wiring to relays, power top circuits, etc. The wiring harness will melt and the wiring will begin to short as the insulation fails. In many cases, the sound-proofing material under the carpeting will begin to smolder and smoke. Also the lining of the E-brake cables will melt, seizing the cables. The smoldering insulation is sometimes mistaken as a dashboard electrical fire, but the tunnel above the converter is the source. To prevent this type of damage, inspect your customer's heat shield regularly. If it is rusted, replace it. Do your customer this great service and spare yourself the grief of having to repair a melted wiring harness. Trust me, there are easier ways to make a living than that job!
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Copyright (c) 1996-2008. Automotive Service Association. All rights reserved.
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