2017 Bolt EV tapping noise

Discussion in 'Bolt EV' started by Walter, Feb 27, 2018.

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  1. Walter

    Walter New Member

    We purchased our 2017 Bolt EV in early June 2017 and now have about 5000 miles on it. So far, we've been very pleased with the car. However, a few months ago, the car started to make a rapid tapping sound when the door is opened and the car started. At first, the sound was very intermittent and went away with a brief tap on the brake pedal. Now it's more frequent and some times comes on even while driving, then goes away. I could easily trace the sound to the brake master cylinder.

    We took the car to a Chevy dealer who confirmed that the sound was not normal. They could not determine what the cause was, so they recorded the sound and contacted GM. The latest from GM is that they will be sending out a part called an "I Brake". Neither the service guy at our local Chevy dealer, nor the certified Bolt technician have heard of such a part, and I couldn't find anything online to identify the part either.

    If anyone in Boltsville has had a similar issue, or knows what an I Brake is, I would appreciate you sharing this with the group and myself.
    Domenick likes this.
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  3. WadeTyhon

    WadeTyhon Well-Known Member

    I haven’t noticed a tapping sound on my Bolt or seen anyone with that specific issue. I haven’t heard of the part either.

    Do you have a recording of the sound by chance?
  4. Walter

    Walter New Member

    I recorded the tapping noise with an iPhone and tried uploading it here as a mp3 file, but this forum doesn't seem to want to accept an mp3 extension.
  5. WadeTyhon

    WadeTyhon Well-Known Member

    Hmmm dang. I had the same problem with uploading videos. I think Domenick said that short, small sized videos could be embedded but not longer ones. Maybe it is the file size of the mp3.

    @Domenick, do you know if uploading mp3 files is possible on the forum?
  6. I don't believe it is now. I can ask if that is possible, though.
    WadeTyhon likes this.
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  8. Ok, I've put the tapping sound in a video file so we can all hear it. I'm pretty sure it's not from a leaky manifold. :D

    Could it be an air conditioning compressor?

  9. Walter

    Walter New Member

    Makes the noise regardless of whether ac is on or off.
    Domenick likes this.
  10. WadeTyhon

    WadeTyhon Well-Known Member

    Thanks Domenick!

    And yes, my Bolt has never made that noise before. A quick search came up with no description that matches your description or the sound you sent over. You might have come across with something new!

    ...Yaaaaaaay? :( Congrats? :confused:

    My first guess (before hearing the audio) was an issue with the parking break. That can briefly make a grinding thud sometimes when it is engaged on a hill. Or perhaps the TMS. But this audio doesn't really sound like either.

    I wondered what the 'I' in I Brake might refer to. Inductive or induction? Perhaps something to do with the regenerative braking? Possibly but the terminology doesn’t sound correct. Perhaps it is not ‘I’ but insead ‘L’ ? L Brake might possibly refer to regen braking in L mode. Or left brake.

    Unfortunately I'm at a loss just like you are - and I can't find anything to back it up.

    Sorry to hear about this! But it sounds like GM might know what the issue is. Once you find out more from your dealer, could you give us an update in case any one else has this same issue in the future?
    Last edited: Feb 28, 2018
  11. Walter

    Walter New Member

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  13. Walter

    Walter New Member

    Thanks for all the help in trying to trace what's causing the noise. I park on a level driveway, put the car in park and shut it off without ever using the parking brake. It's odd because I get the noise whether the car is on or off (but once it's turned off and locked, the noise goes away) and whether I'm driving or not. When it first started, tapping the brake pedal would make it go away immediately. Now, it takes several brake pedal taps and the noise is overall much more frequent. I'll post as soon as I've heard something. Overall, it's been a great car, and it's running on Florida sunshine!
    WadeTyhon likes this.
  14. PureDigital

    PureDigital New Member

    I think it is a faulty vacuum pump that evacuates the power brake accumulator for the master cylinder assist diaphragm. Something normally done on an ICE car by tapping a vacuum line from the intake manifold that is always under partial vacuum
    WadeTyhon and Domenick like this.
  15. WadeTyhon

    WadeTyhon Well-Known Member

    Does the Bolt EV use Bosch iBooster? Your message triggered a memory of reading that the Bolt *might* use the iBooster. And a quick search came up with articles or posts that the Bolt "maybe" and "probably" but not "definitely" uses the iBooster.


    If so, could this be the 'IBrake'?

    Other than the naming similarity, it would make sense considering PureDigital's observation and the fact that you were able to stop the thumping noise by depressing the brake pedal.
  16. Walter

    Walter New Member

  17. Walter

    Walter New Member

    Bingo! Just got off the phone with GM and they confirmed that a Booster was ordered. They gave me the part number and when I looked it up, sure enough it looked like the Bosch iBooster that is common to hybrids and EVs. So I give those commenters on this thread who guessed right, "The Click and Clack Award". If you're ever in the Miami area, I'll buy you a beer. Will post something to let you know how it all worked out.
    WadeTyhon and Domenick like this.
  18. WadeTyhon

    WadeTyhon Well-Known Member

    Glad we could help! What an honor it is to receive the click and clack award! Now we just need our own radio show ‘EV talk’ on NPR.

    Sure, GM already knew what to do. But still. ;) This post might help someone in the future if their service tech isn’t able to diagnose it either.

    Thanks for letting us know! Hope to hear that your EV is nice and silent again very soon.
  19. Walter

    Walter New Member

    I love the idea for "EV Talk". Can you imagine the car sounds callers would mimic? Or would it be no sound at all?
    Domenick and WadeTyhon like this.
  20. PureDigital

    PureDigital New Member

    Hey walter

    Glad I could help with my diagnosis of what was going on with that sound at the brake master cylinder. Before you had the sound file up, I thought that was probably what it was, and the sound file just confirmed it. So I posted. This should be a usefull post for others that have the problem. It was sad that nobody at the dealership had a clue, but obviously the sound file was useful to someone at GM Corp so they could get the right part shipped out to you.

    As to buying me a beer. I live in Oregon and have never been to Florida.:rolleyes: But I might drive there in my Tesla Model 3 to see a Falcon Heavy, or a BFR launch:). I just today got my Invitation to configure my 3 and hit the "Hold My Place" botton because My Wife and Daughter and I want the AWD version. If I had chose the current production car we would have had it in 3 to 6 weeks. Its saying "Mid Year" for the AWD. Ive waited almost 2 years already, whats a few more months, I am Patient:D If I end up down there in Florida for a launch, perhaps I will look you up. I don't drink beer, and I would not hold you to that if I did, but perhaps we can still meet up and you can tell me about how you like your Bolt after a couple of years:)
  21. Walter

    Walter New Member

    Again, I appreciate the help very much. Just wish I had posted earlier, but hadn't registered yet. At least if there are other Bolt owners who have the same problem this will serve as a record. Congrats on the Model 3 order. Looks like a really great car. A friend and neighbor of ours was able to get his hands on one so they are arriving into the South Florida area.

    I love our Bolt so far. Range has been better than expected, and I really like the regenerative braking. In city driving, which is what we mainly do, we get over 300 miles. We drive both city and highway with one pedal. Also like some of the features like the bird's eye surround camera and that I can put up navigation on the screen with Apple Car Play. It's our only car so road trips are still a bit like the Wild West as the charging infrastructure is nothing yet like Tesla's. And speaking of Tesla, I ordered a Powerwall 2 last October and am patiently waiting like you are for your Model 3. It would be nice to have it installed before hurricane season begins in June. We're producing enough energy off our rooftop solar to offset all our home's usage including charging the Bolt and a battery would make it a trifecta. My girlfriend is county coordinator for solar co-ops so we're hoping to see batteries complementing residential solar soon.

    Was glued to the TV when Falcon Heavy lifted off from the Cape. We were out of our seats cheering it on. Now want to go to see the next launch live, but it's a long drive, and if the launch gets scrubbed . . . . .

    Anyway, hope you can make it down with your new car and maybe we can do coffee instead. Thanks again for all your help.
  22. PureDigital

    PureDigital New Member

    Hey Walter
    Im Getting the 3 Specificly as a road car for trips, I have a 13 Leaf right now and will give that to the Daughter when the Tesla shows . I drove the Bolt in Jan 17 and realy liked it. I had never driven an EV with a better regen than that Bolt, it is outstanding. and I have driven all the good EV's. I had my M3 reservation since 3/31/16, and was one of the line standers, (75th order in Oregon). I got to drive a new 18 Leaf last December and It is miles ahead of my Leaf for regen. I like it a lot too, But I lke the Bolts better. The 18 leaf has nicely integreted brakes with their ePedal, but it blends friction brakes for low speed and final stop. I like the Bolts system Better because it uses a logarythmic ramp in their regen controler to up the curent as the RPM falls all the way to a stop in an effort to make the braking quite linear and predictable, and it is. That is definitly a more efficient system than the new Leafs. Because I live in the NW I need a car with a heat pump for local driveing. I had heard that the second year Bolt was going to have one, but allass it did not happen. I cant afford 2 new cars in the same year, so I might buy a Bolt off of lease next year and just live without the heat pump. But in my leaf it makes a huge difference vs no heat pump. In summer I average 5.1 mi/kWh, in winter I avg 4.1 and I bundle up and dont run the heat till the temps hit the mid 40s. If I use the heat in the 40s because I have passengers, I get about 3.8 mi/kWh. I have heard Bolts here go down to 2.8 to 3 Mi/kWh in slow in town driving with heat on. That FH launch was totally Awsome and the twin booster landings were the cherry on that cake. Most excited I have been about a rocket launch since the I saw Apollo 11 go.:) Thanks for the kind offer of coffee, it was a pleasure.
  23. Walter

    Walter New Member

    Just got an update from my local Chevy dealer who is making the repair. Our Bolt has been in their shop since Monday. The new iBooster part has been installed, but apparently, it takes a long time to bleed the brakes. Got fingers crossed that all will go well.
    Domenick likes this.

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