The following description outlines the procedure for bleeding the clutch slave cylinder of E36 M3 models equipped with an SMG transmission. This process is crucial when replacing the SMG pump or servicing the SMG system, as it can help prevent the introduction of air into the system.
Procedure:
- Detach the SMG clutch slave cylinder from the bell housing. Ensure the fluid line remains connected to the slave cylinder throughout the process.
- Compress the slave cylinder push rod into the clutch slave cylinder and maintain its position. A special tool (BMW 21 5 030) is available for this step.
- Fill the main reservoir with hydraulic fluid. Loosen the bleeder screw on the secondary reservoir until fluid begins to escape, then close the screw and refill the main reservoir.
- Attach a special tool to pressurize the reservoir to 2.5bar/36psi. This can be a BMW or aftermarket tool, exclusively used for SMG. BMW tool numbers: 21 5 010 (reservoir cap adaptor)
17 0 002 (pressure pump) Warning: Tools that come into contact with hydraulic fluid during this procedure should not be used for other systems such as brakes. The fluid utilized in the SMG system can damage seals not designed for hydraulic fluid, causing system damage. - Connect the bleeder hose and container to the clutch slave bleeder screw (using tool 21 5 020). Hold the clutch slave in a position where the bleed screw is at the highest point and open the bleeder screw.
- Once bubble-free fluid starts to flow, slightly extend the push rod before returning it to the compressed position. Warning: The slave cylinder push rod should not be released from compression at any point, as this can cause it to be forcibly ejected from the clutch slave cylinder.
- If no air bubbles are present, close the bleeder glove. The main reservoir may need to be re-filled and re-pressurized to 2.5bar/36psi at this stage.
- Depressurize and remove the special tools from the main reservoir.
- Gradually extend the slave cylinder push rod and remove the special tool.
- Reattach the slave cylinder to the bell housing.
- Ensure the main reservoir fluid level is full.
- Carry out the bleeding procedure with the diagnostic tool. Note: Monitor the main reservoir for top-ups, as residual air may be pumped into the reservoir during diagnostic bleeding.
