Sound when in reverse.

[tbeard]

I've had my 2015 i3 since July and I've notice now and again, a thumping noise when I put the car in reverse and start to back out. Has anyone else heard this sound or knows what it could be?

 

[i3atl]

It will do it even while in Park - the general consensus is that it's an ABS check/test the car does sometimes, but I'm not convinced of that.

It's very concerning the first time it happens...I thought something had bumped into my [parked] car. Whatever it is, it doesn't seem to be an issue.

 

[ASUN]

I have heard the same thing...

It seems to happen when I stepped on the brakes to put the car in gear.

Thinking there may be moisture in the brakes from rainy weather that causes the thump?

 

[Stevei3]

Hi guys, if this happens if you have a BEV with heatpump just after pressing 'Start' it is normal and can be related to a threeway-valve in the climate control system or something.
Regards, Steven

 

[i3atl]

Thanks Steven!

That would make more sense than the brake explanation. Do you have any additional info about the valve/behavior that causes this?

 

[Stevei3]

Hi,
it has been discussed on the German Goinelectric forum. How's your German ?

If I may link to them, see: http://www.goingelectric.de/forum/bmw-i3-antrieb-elektromotor/klonk-t7043.html

It seems to happen more often when the temperature drops. Always in the first 1-100 meters of driving. It looks like it is not dependant on going forward or reverse. And it seems the sound is heard only once after start.

Since I have a REx, I have never experienced this sound myself. The BEV of one of our close friends has been making the 'Klonk' sound as mentioned on the German forum since two years though.

Regards !
Steven

 

[tbeard]

Thanks for the replies. I don't have the Rex. I thought it could be a regeneration issue? It doesn't happen every time but when it does it's loud enough I notice it.