BMW R 1150 GS Crankshaft Seal Replacement

The BMW R 1150 GS is a renowned machine, celebrated for its versatility and ruggedness. However, like any high-performance motorcycle, it requires diligent maintenance to keep it running optimally. One crucial but often overlooked component is the radial shaft seal. These seals are vital for preventing leaks of essential fluids, such as oil, from critical areas of the engine and drivetrain. A leaking radial shaft seal can lead to a loss of lubrication, potential component damage, and environmental concerns. This guide will walk you through the process of replacing a radial shaft seal on your BMW R 1150 GS, specifically focusing on the crankshaft seal, a common area for potential leaks.

Understanding Radial Shaft Seals

Radial shaft seals, also known as oil seals or lip seals, are designed to prevent the leakage of lubricants and contaminants from rotating shafts. They typically consist of a metal casing, an elastomeric sealing lip that rides against the shaft, and sometimes a garter spring to maintain pressure on the lip. The constant friction and heat generated by the rotating shaft can cause the seal material to degrade over time, leading to hardening, cracking, and eventual leakage. Identifying a leaking radial shaft seal is usually straightforward; look for oil or grease around the shaft where it exits a housing, such as the engine casing or gearbox.

When to Replace Radial Shaft Seals

Several indicators suggest that your radial shaft seals may need replacement:

• Visible Oil Leaks: The most obvious sign is oil or grease residue around the shaft where the seal is located.
• Decreased Fluid Levels: Consistently low oil or gearbox fluid levels, even after topping up, can point to a leak.
• Contamination: If you notice grease or oil on other engine components that shouldn't be there, it's a strong indicator of a faulty seal.
• Age and Mileage: While not a direct indicator, seals do degrade over time. If your motorcycle has high mileage or has been sitting for extended periods, it's good practice to consider replacing seals as a preventative measure, especially during major engine work.

Tools and Materials Required

Before you begin, ensure you have the necessary tools and materials. For replacing a crankshaft radial shaft seal on a BMW R 1150 GS, you will likely need:

Procedure for Replacing the Crankshaft Radial Shaft Seal (Clutch End)

The BMW R 1150 GS Repair Manual (Order No. 01 79 0 021 120) provides detailed instructions. The following outlines the general steps for replacing the crankshaft radial shaft seal on the clutch end. This is a complex procedure that often requires significant disassembly of the engine.

Step 1: Preparation and Disassembly

1. Safety First: Ensure the motorcycle is on a stable, level surface. Disconnect the battery, negative terminal first.
2. Access: To access the crankshaft seal on the clutch side, you will need to remove the engine from the frame. This is a substantial undertaking. Consult the manual for the detailed procedure for removing the engine (Section 11.15).
3. Drain Fluids: Drain the engine oil and gearbox oil as per the maintenance schedule (Section 00.22 and 00.23).
4. Clutch Removal: With the engine removed, you will need to remove the clutch assembly. This involves unbolting the clutch cover and carefully removing the clutch plates and pressure plate.
5. Lock the Crankshaft: To prevent the crankshaft from turning during disassembly, use the special tool BMW No. 11 5 640 to lock the clutch housing. This is crucial for safely removing other components.
6. Remove Clutch Housing: Once the clutch is disassembled and the crankshaft locked, you can proceed to remove the clutch housing.

Step 2: Removing the Old Radial Shaft Seal

1. Locate the Seal: The crankshaft radial shaft seal is typically located behind the clutch housing, pressed into the crankcase.
2. Careful Extraction: Using a suitable screwdriver or pry tool, carefully lever out the old radial shaft seal. Be extremely cautious not to scratch the sealing surface of the crankshaft or the crankcase.
3. Alternative Removal Method (if necessary): The manual suggests using an awl (BMW No. 00 8 583) to carefully punch a hole in the seal. Then, screw in a pull rod (BMW No. 00 8 581) and use an impact weight (BMW No. 00 8 582) to remove the seal. Again, extreme care must be taken to avoid damaging the surrounding components.

Step 3: Installing the New Radial Shaft Seal

1. Clean the Area: Thoroughly clean the bore where the seal sits in the crankcase and the sealing surface of the crankshaft. Ensure there is no dirt, old seal material, or debris.
2. Lubricate the Seal: Lightly lubricate the lip of the new radial shaft seal with a suitable oil or grease.
3. Driving the Seal: Use the correct BMW special tool, such as BMW No. 11 5 680, to carefully drive the new radial shaft seal into place. Ensure it is driven in straight and to the correct depth. Do not use excessive force, as this can damage the seal or the housing. The tool should have a sliding sleeve to guide the seal correctly.
4. Pre-shaping the Seal: The manual notes to slide the new seal over the taper on the sliding sleeve, pre-shape it, and then pull it off. This helps the seal conform to the shaft's shape.

Step 4: Reassembly

1. Reinstall Clutch Housing: Fit the clutch housing back onto the crankshaft, ensuring it is correctly aligned.
2. Reinstall Clutch Components: Reassemble the clutch pressure plate and plates, ensuring they are installed in the correct order and orientation.
3. Tighten Clutch Housing Bolts: Tighten the clutch housing bolts to the specified torque. Refer to the tightening torque table (Section 00.7).
4. Reinstall Engine: Carefully reinstall the engine into the motorcycle frame, following the reverse procedure of its removal. Ensure all mounting bolts are correctly torqued.
5. Refill Fluids: Refill the engine with the correct grade and quantity of oil and the gearbox with the appropriate hypoid gear oil.
6. Reconnect Components: Reconnect all electrical connectors, fuel lines, cables, and other components that were removed for engine access.
7. Final Checks: Reconnect the battery. Turn on the ignition and cycle the throttle to allow the Motronic unit to register the throttle position. Check for any warning lights.

Important Considerations and Tips

• Refer to the Manual: This guide is a general overview. Always consult the official BMW R 1150 GS Repair Manual for precise procedures, torque values, and specific tool requirements. The manual is your definitive source of information.
• Cleanliness is Paramount: Maintaining a clean working environment is crucial when dealing with engine internals. Any dirt or debris introduced can cause significant damage.
• Use Genuine Parts: For critical components like seals, using genuine BMW parts ensures the best fit and longevity.
• Torque Specifications: Always adhere to the specified torque values. Overtightening or undertightening fasteners can lead to component failure or leaks.
• Take Your Time: This is not a quick job. Rushing the process increases the risk of making mistakes. Plan ample time for the repair.
• If Unsure, Seek Professional Help: If you are not comfortable with the complexity of engine disassembly and reassembly, it is highly recommended to have a qualified BMW technician perform the work.

Frequently Asked Questions (FAQ)

Q1: How do I know if I need to replace a radial shaft seal on my BMW R 1150 GS?
A1: Look for visible oil leaks around the shaft where the seal is located, or a consistent drop in oil or gearbox fluid levels.

Q2: Is it possible to replace the crankshaft seal without removing the engine?
A2: For the crankshaft seal on the clutch side, engine removal is generally required due to the extensive disassembly needed to access the seal. Seals in other locations might be more accessible.

Q3: What is the specific BMW tool number for installing the crankshaft seal?
A3: The BMW manual references tool 11 5 680 for driving in radial shaft seals.

Q4: Can I use a generic oil seal instead of a BMW genuine part?
A4: While generic seals might fit, it's strongly recommended to use genuine BMW parts for critical engine components to ensure proper fit, material quality, and longevity. Using a non-specified seal could lead to premature failure.

Q5: How much engine oil does the R 1150 GS take?
A5: According to the service data, the R 1150 GS takes approximately 3.75 litres (6.6 Imp. pints) with an oil filter change.

Replacing a radial shaft seal, especially on the crankshaft, is a significant mechanical task. Proper preparation, the right tools, and meticulous attention to detail are essential for a successful outcome. By following the official BMW repair manual and taking your time, you can ensure your R 1150 GS remains a reliable companion on all your adventures.