Air Bypass Valve, Turbocharger
NORMALLY CLOSED BYPASS VALVESNormally Closed Air Bypass Valves:
1. Disconnect the air supply hose, At the valve outlet.
2. Remove the vacuum line at the vacuum nipple, and verify vacuum is present. Vacuum must be present at the nipple before proceeding.
NOTE: The vacuum line may contain vacuum restrictors and/or vacuum delay valves which may need to be bypassed or removed, due to their effect on the vacuum signal.
3. With the engine at 1500 rpm and the vacuum line connected to the vacuum nipple, air pump supply air should be felt and heard at the air bypass valve outlet.
4. Disconnect the vacuum line, with the engine at 1500 rpm. Air at the outlet should be shut off, or significantly decreased. Air pump supply air should be felt or heard at the dump port or silencer ports.
5. If the above tests are not successfully completed by the normally closed air bypass valve, check the air pump. If the air pump is operating satisfactorily, replace the air bypass valve.
NORMALLY OPEN AIR BYPASS VALVES WITHOUT VACUUM VENT
Normally Open Air Bypass Vales Without Vacuum Vent:
1. At the valve outlet, disconnect the air supply line.
2. Disconnect the vacuum line at the vacuum nipple.
3. Air should be heard and felt at the valve outlet, with the engine at 1500 rpm.
4. Connect a direct vacuum line that is free from restriction from any manifold vacuum source to the vacuum nipple on the air bypass valve. Air at the outlet should be shut OFF.
5. Air pump supply air should be felt or heard at the silencer ports during the momentary dump. Restore all original connections. If the tests above are not completed satisfactorily, check the air pump. If the air pump is operating satisfactorily, replace the air bypass valve.
NORMALLY OPEN WITHOUT VACUUM VENT
Normally Open Without Vacuum Vent:
1. At the valve outlet, disconnect the air supply line.
2. Disconnect the vacuum line at the vacuum nipple.
3. Air should be heard and felt at the valve outlet, with the engine at 1500 rpm.
4. Connect a direct vacuum line that is free from restriction from any manifold vacuum source to the vacuum nipple on the air bypass valve. Air at the outlet should be shut off or decreased momentarily.
5. Air pump supply air should be felt or heard at the silencer ports during the momentary dump. Restore all original connections. If the tests above are not completed satisfactorily, check the air pump. If the air pump is operating satisfactorily, replace the air bypass valve.