10/01/2016
Owning a Mercedes-Benz W124, whether it's an E220 from 1994 or any other variant, means embracing a legacy of engineering excellence. These vehicles are renowned for their robustness and longevity, but like any finely crafted machine, they thrive on diligent maintenance. Neglecting crucial service items can lead to costly repairs and compromise the very reliability that makes these cars so beloved. This article will guide you through some fundamental maintenance tasks, from safely raising your W124 to the often-misunderstood process of changing your transmission fluid, ensuring your cherished classic continues to deliver that signature Mercedes driving experience.
Proper maintenance not only extends the life of your vehicle but also enhances its performance and safety. While some tasks might seem daunting, with the right knowledge and tools, they are well within the capabilities of the keen DIY enthusiast. Let's delve into the specifics that will help you keep your W124 in peak condition.
Safely Jacking Up Your W124: A Foundation of Safety
Before any under-car work can commence, ensuring your vehicle is safely raised and supported is paramount. This is not a step to be rushed or taken lightly, as improper jacking can lead to serious injury or damage to your car. The W124 has specific jacking points designed to support its weight securely.
Tools Required for Safe Lifting:
- A sturdy hydraulic floor jack
- At least two robust jack stands
- Wheel chocks
- Gloves (for protection)
- A level, firm surface (e.g., concrete garage floor)
The Procedure for Raising Your W124:
Begin by parking your W124 on a level, solid surface. Engage the parking brake firmly and place wheel chocks behind the wheels that will remain on the ground. For example, if you're lifting the front, chock the rear wheels. If lifting the rear, chock the front wheels.
Locate the designated jacking points on your W124. These are typically reinforced areas along the sills or chassis, often indicated by small arrows or specific pads. Consult your owner's manual if you are unsure. Position your hydraulic jack precisely under the chosen jacking point. Slowly raise the vehicle until it reaches the desired height. Once lifted, immediately place jack stands under the appropriate support points near the jacking point. These stands, not the jack itself, will bear the vehicle's weight. Lower the car gently onto the jack stands, ensuring they are stable and correctly seated. Give the car a gentle nudge to confirm its stability before proceeding with any work underneath.
Remember, a hydraulic jack is primarily for lifting, not for supporting a vehicle during work. Always use jack stands for support.
The Critical Transmission Fluid Change: Dispelling Myths
One of the less common, yet incredibly vital, maintenance tasks for your W124 is changing the transmission fluid. For many years, some manufacturers, including Mercedes-Benz at one point, perpetuated the idea of "lifetime" transmission fluid, suggesting it never needed changing. Experience, however, has proven this to be an overly ambitious claim. Transmission fluid, like engine oil, degrades over time due to heat, friction, and contamination, losing its lubricating and cooling properties. Regular fluid and filter changes are essential for the longevity and smooth operation of your W124's automatic gearbox.
Why Change Transmission Fluid?
- Lubrication: The fluid lubricates hundreds of moving parts within the transmission, reducing wear and friction.
- Cooling: It dissipates heat generated by friction, preventing overheating and component damage.
- Cleaning: It carries away wear particles and contaminants, keeping the internal components clean.
- Hydraulic Power: It transmits hydraulic pressure to engage gears and operate clutches.
Recommended Service Intervals:
Typically, it's recommended to change the transmission fluid and filter every 30,000 miles or approximately every two to three years. If your W124 is primarily driven in heavy city traffic, where the transmission cycles more frequently and experiences higher temperatures, you might consider shortening this interval to every 15,000 miles.
Tools and Parts Required:
- Large drain pan (at least 8-10 litres capacity)
- Funnel
- Rags and paper towels
- Large tarp or drip sheet
- 5mm Allen socket (for some pan bolts)
- 13mm socket (for pan bolts on some models)
- 27mm socket (for crankshaft bolt to turn torque converter)
- Torque wrench (essential for pan bolts)
- New transmission fluid (Dextron II or III, or genuine Mercedes-Benz fluid)
- Transmission filter kit (includes filter and pan gasket)
- Dipstick tool (if your W124 doesn't have a permanent one) or infrared thermometer
The Transmission Fluid Change Procedure:
1. Preparation: Safely jack up and support your W124 as described above. Place a large tarp or drip sheet under the work area to catch any spills. Have your drain pan and plenty of rags ready. It's often easier to drain the fluid when the transmission is warm (but not scalding hot), as the fluid will flow more easily.
2. Draining the Pan: Locate the transmission fluid pan underneath the gearbox. Place your drain pan directly beneath it. Using the appropriate socket (5mm Allen or 13mm), carefully loosen and remove the drain plug from the transmission pan. Allow the fluid to drain completely into the pan. This will typically yield about 3 litres of fluid. Once drained, reinstall the drain plug, but do not overtighten it yet.
3. Removing the Pan and Filter: Once the fluid has drained from the pan, carefully remove all the bolts holding the transmission pan in place. Be prepared for a small amount of residual fluid to drip out as you remove the pan. Gently lower the pan, being careful not to spill any remaining fluid. You will see the transmission filter attached to the valve body. Carefully unclip or unbolt the old filter and remove it. Inspect the pan for any metallic particles or excessive sludge, which could indicate internal wear.
4. Draining the Torque Converter (Crucial Step): This step is vital for a complete fluid change, as the torque converter holds a significant amount of old fluid (around 3-4 litres) that does not drain from the pan. To access the torque converter drain plug, you will need to turn the engine manually. Use a 27mm socket on the crankshaft bolt (usually located at the front of the engine, behind the radiator fan). Slowly turn the crankshaft clockwise until you see a small drain plug on the torque converter through the access hole in the bell housing. Position your drain pan underneath and remove this plug. Allow all the fluid to drain. Once empty, reinstall the torque converter drain plug and tighten it securely.
5. Installing New Filter and Pan: Clean the transmission pan thoroughly, removing any old gasket material. Install the new transmission filter onto the valve body, ensuring it clicks or bolts into place securely. Place the new gasket onto the clean transmission pan, or directly onto the transmission housing if it's a pan-side gasket. Carefully lift the pan back into position and start threading all the bolts by hand. It's crucial not to overtighten these bolts, as the pressed metal pan can easily distort, leading to leaks. Torque these bolts to the manufacturer's specified low torque value (often just a few Newton-meters). Some experienced mechanics recommend tightening them evenly until the tabs just start to move, then a little more, or using thread lock to prevent them from loosening.
6. Refilling the Transmission: With the pan and torque converter plugs secured and the new filter installed, it's time to refill. Using a clean funnel, add approximately 3 litres of new, recommended transmission fluid (Dextron II or III) through the dipstick tube. Start the engine and let it idle. With your foot on the brake, shift the transmission through all the gears (P-R-N-D-3-2-1) pausing briefly in each. This helps circulate the new fluid throughout the system. Then, check the fluid level with the engine running and at operating temperature. On W124 models with a dipstick, the level should be between the "min" and "max" marks. If your W124 doesn't have a permanent dipstick, you'll need a special dipstick tool or an infrared thermometer to check the fluid temperature and level. Add fluid gradually, in small increments, rechecking the level each time until it reaches the correct mark. Be careful not to overfill, as this can also cause transmission issues.
Fluid Choice Considerations:
While genuine Mercedes-Benz fluid is always a safe bet, it can be expensive. Many W124 owners successfully use high-quality Dextron II or Dextron III compatible fluids. The key is to use a fluid that meets the required specifications for your vehicle's transmission.
Manual Gearbox Fluid & Clutch Fluid Maintenance
While automatic transmissions often get the spotlight for fluid changes, manual gearboxes and clutch systems also require attention. The fluid in a manual gearbox lubricates the gears, shafts, and bearings, and it also degrades over time. Some W124 manual gearbox owners report that changing the oil as often as the engine oil can significantly enhance the life of components like layshaft bearings.
Manual Gearbox Fluid:
For manual gearboxes, there's a belief that any automatic transmission fluid (ATF) will suffice. However, some Mercedes dealers have specified different part numbers for manual gearbox oil, such as Shell Donax TM, which is often clear rather than the typical red of ATF. A W124 manual gearbox typically takes about 1.5 litres of fluid. Regular changes are highly recommended to maintain smooth shifting and protect internal components.
Improving Manual Gearshift Feel:
Beyond fluid changes, one modification that can dramatically improve the gear change feel in a W124 manual is renewing the rubbers on the gearbox end of the shift rods. These rubbers can soften over time, leading to a sloppy and imprecise gear change, which is often mistakenly attributed to the gearbox itself. Replacing these inexpensive parts can truly transform the driving experience.
Clutch Fluid and Brake Fluid:
The clutch system in a W124, being hydraulically operated, shares fluid with the brake system. The clutch fluid reservoir is actually part of the brake master cylinder reservoir, typically the rear part. Both brake and clutch fluid are hygroscopic, meaning they absorb moisture from the air over time. This moisture can lead to corrosion in the braking and clutch lines and calipers/cylinders, and it lowers the fluid's boiling point, which can cause brake fade under heavy use. It is highly recommended to completely flush and replace both brake and clutch fluid every two years, regardless of mileage, to ensure optimal braking performance and clutch operation.
When topping up or bleeding the clutch system, be careful as the clutch fluid section of the reservoir can be difficult to access and fill precisely.
W124 Fluid Capacities and Specifications (Approximate)
| Fluid Type | Approximate Capacity | Notes |
|---|---|---|
| Automatic Transmission Fluid (Pan only) | 3 Litres | Requires Dextron II/III or MB equivalent |
| Automatic Transmission Fluid (Total, with Torque Converter) | 6.5 Litres | Full flush requires draining torque converter |
| Manual Gearbox Fluid | 1.5 Litres | Shell Donax TM or specified MB fluid |
| Brake/Clutch Fluid | Varies | Dot 4 recommended, flush every 2 years |
Note: Always consult your specific W124 owner's manual or a trusted workshop manual for precise capacities and fluid specifications for your model year.
Frequently Asked Questions (FAQs)
Q: Can I use any ATF in my W124 automatic transmission?
A: While many W124s can use Dextron II or Dextron III compatible fluids, it's crucial to ensure the fluid meets the specific Mercedes-Benz specifications. Using an incorrect fluid can lead to transmission damage. Genuine MB fluid is always the safest option, but high-quality aftermarket alternatives are available if they explicitly state compatibility.
Q: How do I know if my transmission fluid needs changing?
A: Beyond the recommended mileage/time intervals, look for signs like dark, burnt-smelling fluid, harsh or delayed gear shifts, or slipping. However, by the time these symptoms appear, damage may already have occurred. Regular preventative changes are best.
Q: Is it really necessary to drain the torque converter?
A: Yes, for a complete fluid change, draining the torque converter is highly recommended. It holds a significant portion of the total fluid volume, and leaving old fluid in means you're mixing new fluid with a large amount of degraded fluid, reducing the effectiveness of the change. If you only drain the pan, you're essentially performing a partial fluid change.
Q: My W124 manual gearshift feels sloppy. Is it the gearbox?
A: Not necessarily. A common cause of a sloppy manual gearshift in W124s is worn or soft rubbers on the gearbox end of the shift rods. Replacing these inexpensive parts can often restore a precise and firm gear change feel, avoiding unnecessary gearbox condemnation.
Q: Where exactly is the clutch fluid reservoir on a W124?
A: The clutch fluid reservoir is integrated with the brake master cylinder reservoir. It's typically the rear section of the combined reservoir. When bleeding or topping up the clutch, you'll be accessing this part of the brake fluid reservoir.
Conclusion
Maintaining your Mercedes-Benz W124 is a rewarding endeavour that ensures its continued performance and reliability for years to come. By understanding the importance of safe jacking procedures, committing to regular transmission fluid and filter changes, and not overlooking the manual gearbox and clutch fluid, you can prevent common issues and preserve the legendary qualities of these classic vehicles. Remember, a well-maintained W124 is not just a car; it's a testament to enduring engineering and a joy to drive. Invest the time and effort, and your W124 will repay you with countless miles of motoring pleasure.
If you want to read more articles similar to Essential W124 Maintenance: Jacking & Fluids, you can visit the Maintenance category.