Test pressurizing the turbo system
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Test pressurizing the turbo system
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Saab 900 turbo.
Complaints of poor boost pressure or that the engine seems lacking in power and sluggish may in certain cases be due to leakage in the delivery side of the turbo system.
This SI describes methods of checking the integrity of the turbo system by pressurising it to 1 bar and carrying out visual inspection for possible leakage.
The method is described first. This is then followed by tips on checking the intake manifold and charge air bypass valve.
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1.
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Detach the delivery hose from the turbocharger and fit plug 83 94 587. Tighten the hose clip.
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2.
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Detach the delivery hose from the throttle housing and fit the plug with nipple, part No. 83 94 595. Tighten the hose clip.
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3.
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Connect pressure measuring equipment 83 93 514 to the plug with nipple.
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Important
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Exercise caution when pressurizing the turbo system! Excessive pressure could damage hoses and connections.
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4.
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Connect a compressed air gun to the pressure measuring 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 in 30 seconds. If it drops by more than this or if a hissing sound can be heard, check the hoses, pipes and connections for leakage.
Exercise care when using the compressed air gun. The pressure increases rapidly and could easily damage hoses and connections.
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5.
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When you have finished pressurizing and checking the system, disconnect the measuring equipment and connect the delivery and vacuum hoses.
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Checking the turbo's intake pipe
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Remove and inspect the intake manifold and the hoses between the mass air flow sensor and turbocharger for possible cracks.
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Checking the charge air bypass valve
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Check the operation of the charge air bypass valve by building up a vacuum in the valve's vacuum hose by means of the pressure-vacuum pump. Check that the valve has opened (blow into it!) and that the vacuum remains (the diaphragm in the valve is intact).
Illustrated are the special tools used when pressurizing the turbo system.
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1.
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Plug for turbo delivery hose, part No. 83 94 587
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2.
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Ditto with nipple, part No. 83 94 595
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3.
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Pressure measuring equipment, part No. 83 93 514
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4.
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Pressure-vacuum pump, part No. 30 14 883
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