Replacing Thermal Paste Behind Mercedes Benz EZL unit

Faiz Jan • 5 August 2019

Hello, I want to share how to replace the thermal paste behind the precious EZL unit, there is a thin layer of white thermal paste that the factory used between the bottom of the EZL unit and the inner fender, so that heat generated by the EZL could be transferred to a larger and cooler area.

I was reading about this for a while before I jump in and replace it, Mercedes Benz recommendation to replace it every ten years.

During the years the thin layer tends to dry up, flake off the EZL reducing its ability to transfer the heat to the body of the car, this will cook the ELZ parts from inside. 20-30 minutes of your time will save an expensive part with less than $10, or if your EZL on its last leg that will add maybe a couple of years to its life before it completely dies.

What you will need

  • Thermal paste, I used "Super Thermal Grease II" from MG chemical, I bought it from an electronics store outlet for $8. 
  • Rubber gloves
  • Any solvent your choice to clean the EZL
  • Paper towels
  • Razorblade
  • 10mm socket
  • Food wrap

Instructions

  1. Carefully remove the electrical connectors and one vacuum connection from the EZL and fold them aside. so they are out of the way.Picture 1
  2. Loosen and remove the three nuts that secure the EZL to the car's inner fender.
  3. Clean the inner fender-well area, as well as the back of the EZL using a good solvent, I used my wife's nail polish remover and left it open and she is mad right now , that thing evaporates so fast, use your razor blade to lightly scrape the excess for the hard dried stains. Be careful not to clean the face of the EZL with the solvent because that will erase the bar code and the model ... etc. of the EZL.

     inner fender-well area, as well as the back of the EZL using
  4. Spread a layer of thermal paste on the back of the EZL. You want the layer to be 1-2mm thick -- no less or no more.

    Spread a layer of thermal paste on the back of the EZL.
  5. I found out that when you buy a new EZL, there is a film to protect the paste, I checked online, and everybody used food wrap instead during the past years, it will disintegrate by age, heat ... etc., the film still there on my EZL and the film in a good shape, so I think it has been replaced during the last five years as i don't believe this is a 30+ years paste and film.use your old film if yours worth saving, I checked with 3 different electronic stores in Houston (Micro center, Houston electronic outlet and Fry's) they confirmed that there is nothing these days called "Thermal conductive film", and the thermal paste developed through out the years, they also said that its only to prevent making a huge mess with the paste while working on the vehicle at the factory when they assembled the vehicles, but i believe since the part is not Mercedes Benz part, its Bosch manufactured by Siemens they used that film to protect the paste while shipping the part to MB warehouses, its your call to use a wrap from not , nothing will happen, if you don't know the history of your EZL just go ahead and replace it. better than being sorry later. 
     there is a film to protect the paste,
  6. Trim the access of the wrap using a blade, do no disturb the thickness of the paste, carefully smooth it with your fingers.

     Trim the access of the wrap using a blade

     

  7. Re-install the EZL onto the car's inner fender using the exact reverse of the removal process.Re-install the EZL onto the car's inne

The 104 engine service manual says in section 15-2093 - Removal and installation of EZL/AKR ignition control module.

Heat conducting paste has been applied to the rear of the control module and covered with heat-conducting protective foil for improved heat dissipation. The protective foil must not be removed.

Additional Photos

Replacing Thermal Paste Behind Mercedes Benz EZL unitReplacing Thermal Paste Behind Mercedes Benz EZL unitReplacing Thermal Paste Behind Mercedes Benz EZL unit

 

 

 

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