Mercedes-Benz GLC X253 (2015-2023) Transmission Shudder During Acceleration

Symptoms

• Noticeable shudder or vibration during acceleration, especially from a stop or low speeds.
• Possible jerking sensation when shifting gears.
• Increased engine RPMs without corresponding vehicle speed increase.
• Check Engine Light may or may not be illuminated.

Diagnostic Steps

1. Visual Inspection

   • Check under the vehicle for any fluid leaks (transmission fluid or engine oil).
   • Inspect the transmission mounts for any signs of wear or damage.
   • Look for any obvious signs of damage on the driveshaft and CV joints.

2. Check Transmission Fluid

   • Ensure the transmission fluid is at the correct level and is in good condition (not burnt or contaminated).
   • Tools Required: Transmission dipstick (if applicable) and a clean rag.

3. Scan for Diagnostic Trouble Codes (DTCs)

   • Use an OBD-II scanner to check for any stored codes related to the transmission or engine.
   • Note any codes that may indicate a transmission fault.

4. Check for Software Updates

   • Ensure the vehicle's transmission control module (TCM) is updated with the latest software by consulting with a Mercedes-Benz dealer.

5. Test Drive

   • Perform a test drive to replicate the issue. Pay attention to conditions that trigger the shudder (e.g., cold start, hot engine, different speeds).

Tools Required

• OBD-II scanner
• Torque wrench
• Transmission fluid pump
• Fluid catch pan
• Socket set and wrenches
• Screwdrivers
• Transmission fluid (Mercedes-Benz approved)
• Clean rags
• Jack and jack stands

Repair Instructions

Step 1: Check and Change Transmission Fluid

1. Locate Transmission Fluid Dipstick or Drain Plug

   • For models with a dipstick, locate it under the hood. For others, you may need to access the drain plug.

2. Check Fluid Level

   • Pull the dipstick, wipe it clean, reinsert, and check the level.
   • If you have a drain plug, use a socket wrench to loosen it and check fluid condition.

3. Change the Fluid (if necessary)

   • If the fluid is low or dirty, replace it.
   • With the vehicle level, place a fluid catch pan under the transmission.
   • Remove the drain plug, allow fluid to drain completely, and replace the plug.
   • Use a transmission fluid pump to refill the transmission with new, approved fluid through the dipstick tube or fill port.
   • Check the fluid level again after refilling and adjust as necessary.

Step 2: Inspect and Replace Transmission Mounts (if necessary)

1. Lift the Vehicle

   • Use a jack and jack stands to safely raise the vehicle.

2. Inspect Transmission Mounts

   • Look for signs of wear, cracks, or separation on the rubber parts of the mounts.
   • Use a pry bar to check for excessive movement.

3. Replace Mounts

   • If damaged, remove the bolts securing the mount to the transmission and the chassis.
   • Install the new mount, and torque the bolts to the manufacturer's specifications.

Step 3: Check for Software Updates

1. Contact a Dealership
   • Schedule an appointment with a Mercedes-Benz dealership to check for TCM software updates.
   • Have them perform the updates if necessary.

Step 4: Re-Test Drive

1. After Repairs
   • Perform a test drive to ensure the shudder during acceleration has been resolved.
   • Monitor for any abnormal behavior and check again for DTCs using the OBD-II scanner.

Step 5: Additional Diagnostic Steps (if issues persist)

• If the issue persists after fluid change and mount inspection, further diagnostics may be required:
  • Inspect the torque converter for malfunction.
  • Evaluate the condition of the driveshaft and CV joints.
  • Check the transmission control solenoids for proper operation.

Conclusion

Following these steps should help diagnose and resolve transmission shudder issues in a Mercedes-Benz GLC X253. If problems persist after these repairs, consider consulting a professional technician for further evaluation, as internal transmission components may need inspection or replacement.