WIS Document: 8540

| SERVICE INFORMATION | Bulletin Nbr: | 291-1225 | Date:........... | OKTOBER 1991 | Market: | ALL | | Pressure-testing the turbo system | Cars concerned Saab 900 turbo. | Background In the case of complaints about poor boost pressure or that the engine feels low onpower or "sluggish", the reason may sometimes be leakage on the pressure side of the turbo system. This SI describes methods of checking the turbo system for leakage by pressure testing to bar 1 in conjunction with visual inspection for possible leaks. The method for the Saab 9000 is described first, followed by that for Saab 900. At the end ae some hints on checking the inlet manifold and by-pass valve. | Pressure testing | 1. | Remove the pressure hose from the turbo unit and fit plug 83 94 587. Tighten the hose clip. | 2. | Remove the pressure hose from the throttle housing and fit plug with nipple 83 94 595. Tighten the hose clip. | 3. | Connect the pressure testing equipment 83 93 514 to the plug with nipple. | Important | Take great care when pressurizing the turbo system. Excessive pressure can damage hoses and fittings. | | 4. | Connect a compressed air gun to the pressure testing equipment and carefully build up a pressure of about 1 bar in the turbo system. Check that the pressure does not drop by more than 0.1 bar/30 seconds. If the pressure drops more rapidly or a hissing sound is heard, check the hoses, pipes and fittings for leakage Be careful when using the compressed air gun. The pressure rises faster than you would think and can very easily damage hoses and fittings. | 5. | On completion of satisfactory pressure testing and checking, remove the test equipment and reconnect the pressure and vaccuum hoses. | Checking the turbo inlet manifold Remove and inspect the inlet manifold and the hoses between the air mass meter and turbo unit for possible cracks. | Checking the by-pass valve Check the operation of the by-pass valve by creating a vaccum in the valve's vaccuum hose with pressure/vaccuumpump. Check that the valve opens (blow!) and that the vaccuum is not lost (the valve's diaphragm is intact). | Special tools Special tools used for pressure-testing the turbo system | 1. | Plug for turbo pressure hose, part No. 83 94 587 | 2. | Ditto with nipple, part No. 83 94 595 | 3. | Pressure testing equipment, part No. 83 93 514 | 4. | Pressure/vaccuum pump, part No. 30 14 883 | Standard time information Object code: 122 35 Standard time : 0,1 hours 0,1 hours (inspection of dismantled by-pass valve