Vacuum System, Checking

Vacuum system, checking

Special tools:
999 7108 T-pipe 999 7108 T-Pipe
999 5230 PRESSURE METER 999 5230 Pressure Meter

Note! The illustrations in this service information are used for different model years and/or models. Some variation may occur. However, the essential information in the illustrations is always correct.

Preparatory work





Separate the vacuum pump connector.

Check

Checking the pump capacity




Remove the quick-release connector on the vacuum pump. Install: 999 7108 T-pipe 999 7108 T-Pipe with the plugged end on the pump
Connect: 999 5230 PRESSURE METER 999 5230 Pressure Meter on: 999 7108 T-pipe 999 7108 T-Pipe.
Install the connector for the pump. Read off the value on: 999 5230 PRESSURE METER 999 5230 Pressure Meter.
The value must be between 80-90 kPa negative pressure. If not replace the pump. See: Vacuum pump, brake booster, B5254T7 Service and Repair.

Checking the line pressure




Remove the quick-release connector on the vacuum pump. Install: 999 7108 T-pipe 999 7108 T-Pipe between the quick-release connector and the pump.
Connect: 999 5230 PRESSURE METER 999 5230 Pressure Meter on: 999 7108 T-pipe 999 7108 T-Pipe.
Install the connector for the pump. Read off the value on: 999 5230 PRESSURE METER 999 5230 Pressure Meter.
The value must be 60 kPa negative pressure when the pump stops.
Press down the brake pedal a couple of times to start the pump. The value when the pump starts must be 45 kPa negative pressure.
If the pump starts at a negative pressure of 0 - 45 kPa or stops at a negative pressure higher than 60 kPa, replace the control valve. See: Brake booster vacuum hose Brake Booster Vacuum Hose.
If the correct system pressure is not obtained even though the pump capacity is correct, this indicates that there is a leak in the system.

Check for leaks on the intake manifold valve





Remove:
- the clamp and the hose from the vacuum hose
- hose from the intake manifold.
Apply lock grip pliers to the hose for the charge air pipe.
Blow or suck in the hose end that was installed in the intake manifold.
The air flow must only go in the direction of the arrow. If not replace the valve.

Checking for leaks in vacuum hose power brake booster




Remove the hose. See: Brake booster vacuum hose Brake Booster Vacuum Hose.
Check for holes or other damage in the hose.
Blow or suck in the hose ends.
The air flow must only go in the direction of the arrows. If not replace the vacuum hose.

Checking for leaks on the power brake booster
If it is not possible to obtain the correct system pressure after the above checks, this indicates that there is a leak in the power brake booster. In the event of a leak in the power brake booster, replace the power brake booster. See: Brake booster, L.H.D Brake Booster, L.H.D.