I have a 2018 2.5L Outback. When the engine is cold (or the car sit for a while but the engine is still somewhat warmed) under very lite acceleration I can hear a knock coming from the engine.
Here is a link to a video:
https://photos.app.goo.gl/FBu8Yts9uwVzqu828
Best to listen with headphones. It looks like the car is not moving but I have recorded this on a hill and the car is moving slowly under lite throttle.
Some info:
- You can hear this only under lite throttle.
- It gets quieter or is completely gone after a few moments.
- The engine needs to be cold, or sit for a while. Does not have to be 100% cold. With freezing temperatures it actually better reproducible when the engine it somewhat a bit warm but the car was sitting for a hour or so.
- The throttle input needs to be constant to best reproduce this.
The car has about 4k miles but it did this from day one. I'm not going to a dealer with this yet because I talked to them, they have never heard of this problem and will probably take the car for multiple days and will have to disassembly stuff piece by piece until they maybe find something. Better to start with a solid theory.
First question: is this normal?
Second question: if this is not normal than what might cause this?