squishy Posted January 10, 2020 Report Share Posted January 10, 2020 Any ideas what this noise could be? https://youtu.be/u8o9P9-eUW0 It occurs when you start the vehicle as well as while backing up. I assume it happens while driving but you can't hear it from inside the car. Originally I thought it might be a fan going out but upon inspection the main cooling fan on the front of the engine spins up and sounds normal. I've searched around but haven't found any clue as to what this might be. 2013 C-Max Hybrid SEL with just over 70k miles. Quote Link to comment Share on other sites More sharing options...
homestead Posted January 10, 2020 Report Share Posted January 10, 2020 Sounds like Ac/defrost noise. easy to see if that is it. Quote Link to comment Share on other sites More sharing options...
stolenmoment Posted January 10, 2020 Report Share Posted January 10, 2020 Yeah, the AC compressor(?) makes that noise whenever it's running. Horrible. Quote Link to comment Share on other sites More sharing options...
squishy Posted January 10, 2020 Author Report Share Posted January 10, 2020 22 minutes ago, homestead said: Sounds like Ac/defrost noise. easy to see if that is it. @homestead, how would I go about testing that? Quote Link to comment Share on other sites More sharing options...
stolenmoment Posted January 10, 2020 Report Share Posted January 10, 2020 Start it like you did in the video, roll down the window, turn the AC off and back on. Quote Link to comment Share on other sites More sharing options...
squishy Posted January 10, 2020 Author Report Share Posted January 10, 2020 (edited) So I found that I can reproduce the issue at will.. Start car << You'll hear the noise Push in brake pedal and shift into any other gear. Release brake pedal << You'll hear the noise Push in brake pedal and shift back into park Release brake pedal << You'll hear the noise. Also... @stolenmoment, I tried what you said with the AC and it didn't do anything out of the ordinary. Edited January 10, 2020 by squishy Quote Link to comment Share on other sites More sharing options...
plus 3 golfer Posted January 10, 2020 Report Share Posted January 10, 2020 Sounds like the vacuum pump. Quote Link to comment Share on other sites More sharing options...
plus 3 golfer Posted January 10, 2020 Report Share Posted January 10, 2020 (edited) An electric vacuum pump controlled by the ABS supplies vacuum to brake booster chamber when ICE is off - start car, pump starts pulling air from booster. When you push brake pedal in, valve opens allowing air into brake booster assisting pushing the rod / piston into master cylinder. When brake is released, valve closes, pump starts and draws air out of booster and builds vacuum in the booster chamber. Edited January 10, 2020 by Plus 3 Golfer Quote Link to comment Share on other sites More sharing options...
squishy Posted January 10, 2020 Author Report Share Posted January 10, 2020 @Plus 3 Golfer, I assume this noise indicates something is wrong and the vacuum pump should be replaced? Quote Link to comment Share on other sites More sharing options...
plus 3 golfer Posted January 10, 2020 Report Share Posted January 10, 2020 That's typically how it sounds. I believe others (maybe on C-Max Energi Forum which is to be merged into this one) have recorded it also. squishy 1 Quote Link to comment Share on other sites More sharing options...
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