Vacuum Pump: Service and Repair
Replacing sucking jet pumpInstructions and function description
^ As of the 2001 model, a sucking jet pump -1- is installed in Tiptronic vehicles!
^ The sucking jet pump -1- is permanently linked to the hoses -connection A/B/C- and, if replacement is necessary, the entire unit must be replaced!
^ To make connection -C- accessible, the engine must be lowered at the rear!
The sucking jet pump -1- helps to increase the engine vacuum, connection -A-, required for the brake booster, especially during the engine warm-up phase.
Function: by bypassing the throttle -D- (bypass around the throttle from connection -B- to connection -C-), the rate of flow and so the vacuum are increased locally by the sucking jet pump -1-. This greater vacuum is applied to the brake booster connection -A-.
1 Sucking jet pump
A Connection for brake booster
B Connection to air cleaner (ahead of throttle)
C Connection to right intake housing (after throttle)
D Throttle
Removing sucking jet pump
1. Cover the vehicle with protective covers in the rear area in such a way that the body can not be damaged.
2. Remove ignition key.
Note!
^ In order to exclude any damage to other components when lowering the engine, the following operation is necessary!
3. Remove the air cleaner completely and unclip the electrical leads from the right -arrows- and left of the oxygen sensors on the body (illustration shows right side).
4. Lower the engine at the rear and support it with special tool -E- retaining device 9624/1. The engine must be lowered until the transmission almost comes into contact with the rear-axle cross member.
Procedure for this:
- Undo the stabilizer on the rear-axle side sections (4 screws) and secure the retaining device 9624/1 -E-. Turn the pressure screw of the retaining device 9624/1 until the pressure disc -F- reaches its lowest position.
- Position the workshop jack at the rear crankcase -arrow- in connection with a suitable (slip-resistant) intermediate plate (hardwood plate). Place car jack underneath under slight load.
- Undo the engine carrier at the right and left engine mount -arrow = left engine mount-.
- Lower the engine-transmission unit at the rear with the workshop jack in connection with the (slip-resistant) intermediate plate (hardwood plate) on the crankcase -arrow- until the transmission housing is almost in contact with the rear axle cross member.
- In this position, turn the pressure screw of the retaining device 9624/1 -E- until the pressure disc -F- comes into contact with the crankcase. Then remove the workshop jack.
5. Carry out the following disassembly operations:
- Unclip the lead from the holder -2-.
- Unlock and remove the hose -3-.
- Pull off plug -4-
- Undo the screw (M6) from the clamp and remove the clamp -5-.
- Disconnect lead -A- for the brake booster. After removing the snap ring -arrow-, unlock the connection (push the inner sleeve against the outer sleeve) and pull off the lead at the same time.
6. Remove the lead to the right intake housing -C-. After removing the snap ring -arrow-, unlock the connection (push the inner sleeve against the outer sleeve) and pull off the lead at the same time.
7. Remove the sucking jet pump from the engine compartment.
Installing new sucking jet pump
1. Install in reverse order.
2. Install sucking jet pump. Before installing the sucking jet pump, fit (clip on) the retainer -arrow- at the connection -C-. Push the connection -C- on to the angle piece as far as the stop.
Note!
^ The connection -C- of the sucking jet pump must be pushed completely (as far as the stop) -dashed line on to the angle piece (the connection flange)!
^ As this area is not visible, it must be done by feel!
3. Carry out the following assembly operations:
- Clip the lead into the holder -2-.
- Fit hose -3-.
- Push on plug -4-.
- Fit the lead -A- for the brake booster and the snap ring -arrow-.
- Fit the clamp and fasten with screw (M6) -5-.
4. Raise engine with the workshop jack and secure the engine carrier on the right and left engine mounts -arrow = left engine mount- with new fastening nuts. Tightening torque 85 Nm (63 ft. lbs.).
5. Remove the retaining device 9624/1 -E- and fasten the stabilizer on the rear-axle side sections (4 screws).
6. Clip the electrical leads from the right -arrows- and left of the oxygen sensors on the body (illustration shows right side).
7. Install air cleaner assembly.
8. Start the engine and check the intake system for leaks.
9. Check function of brake booster.