Last-ditch Approach To Reviving 108/114/115 Blower Motors


Last-ditch Approach To Reviving
108/114/115 Blower Motors

Ok, here is a last-ditch approach to reviving the heater blower. It's worked for me but not long-term, so don't consider it a permanent fix, just something to delay the inevitable. . .

  • 2-3 ft long piece of small vacuum tubing (the white hard plastic kind from MB)
  • ATF (Automatic Transmission Fluid - any kind)
  • Hand tools
  • Mirror
  • Small flashlight (a little MagLite works well here)
  • Let me preface this by saying that the blower motor must be free to turn and hopefully running, maybe not much. Start by removing the air grille from the air inlet opening. Close the hood after it's removed. With a small inspection mirror and the flashlight take a look around inside the grille area and get yourself oriented with the location of the blower. It sits at an angle pointing down towards the floor of the passenger cabin.

    Take a piece of stiff wire or other suitable material and try to push the blades of the blower to turn it. If you can turn the blower you may be in luck. If not, button things up at this point - there's nothing you can do short of R&R.

    If the blower will turn take the piece of vacuum tubing and experiment with shaping it so you can get it oriented around the back center of the blower. Here's why:

    When you've got it formed just right, dip it into a small container of ATF. Let the ATF wick up into the tubing, then close off the opposite end with a finger, like a straw. Wipe the outside of the tubing off and then feed it down to the blower motor. When you get the end of the tubing positioned over the area where the motor bearings are, take your finger off the tube and let the ATF drip into the motor.

    If the motor works at all this will lube the bushings in it fairly well. Run the motor continuously for a good 5 minutes and listen to see if the speed or pitch changes. If it does then you've accomplished what you set out to do. If not try dripping some more ATF into the motor. After all, what have you got to lose?

    The failure mode I found to be the most common between research and personal experience was either seizure of the motor from dry bearings, or overheating of the motor for the same reason. If the friction gets bad enough the bearings seize. The other failure mode that can mirror this one is dry bearings that cause a high current in the motor due to the additional load (friction) taking place. The heat from the high current melts the brush holders and the brush rigging locks the motor up. This is the most catastrophic, since there's no fix even when the motor is removed.

    I've done the R&R and it's NOT a pleasant job. It's so nasty that it's something that would keep me from buying another 114/115/108 chassis car.

    Dan Penoff







    Ref: Frank Mallory's database and https://mercedes-benz-publicarchive.com