knocking sound
 

Hi Everyone,

After i have driven for about 7-8 miles, when I shut down the car I hear knocking sounds from the engine. The knocking sound continues for a couple of minutes. This is the first car I have owned and I don't know if this is something I need to be worried about. I use chevron fuel with 92 octane rating if that helps.

I am adding a sound clip of the knocking sound. Any tips will be much appreciated.
sound clip

Thanks,
WingRider.

It sounds like the heat shields cooling off on the exhaust. I wouldn't worry about it, its normal.....

Thank you very much for the quick reply!

I have never heard heat shields THAT loud. There's something else going on. You need to crawl around and find out where the noise is coming from. Is it from the engine, underneath or somewhere else?

Heat shields contracting is normal and every car does it, but it's not very loud and every car does it.

The recording is loud but that could be his recording device and where he held the mic, he could also have turned the mic gain up. If he is not over heating or any other problems I would say all in all its a heat shield noise... nothing to worry about

Hello @wingrider and welcome to the sounds of the FR-S/BRZ.......:clap:

Yep, I reckon @FRS Justin has it diagnosed proper.


humfrz

DANG, @guybo ........ clean the wax out of your ears ........ or, maybe your car didn't come with the optional, high volume heat shields ........ :D


humfrz

I used the sound recorder android app. Don't know if it turns the the gain up. I feel that it comes from the engine. Really noob question: you said its the heat shields cooling off the exhaust. Does it mean it will be louder at the back of the car at the exhaust? I can verify that.

The car does not overheat and runs beautifully. Its a joy to drive :)

Yeah, maybe it's the recording. the OP should measure the noise of his car against others though. When my car is turned off hot, it's no louder than other cars.

here is a collection of heat shields


https://www.google.com/search?q=frs+...+shields&imgrc=_


they surround the exhaust pipe to dissipate the heat. It should actually be quieter towards the back because the heat has mostly dissipated...

I would bet money that is drops from the AC line. Water hitting the exhaust. There is a small black tube that drains most of the water coming down under the passenger side floor board. maybe that is clogged. I have never heard my brz make this noise but i have absolutely heard it on many other vehicles. Sounds just like Water from the AC dripping on the exhaust.

It sounds loud .. but is it loud or just such recording loudness level? When i park mine, yes it ticks/knocks, when cooling down, but not that easy to gauge how that "not that loud" on mine is vs this recording, by trying to scale it to other ambient sounds recorded.

After a second listen, it sounds like hail on the tin roof of an empty chicken coop.

If the OP was from Georgia ....... I would figure that's what it was ......:D

:slap: OK, I deserved that.


humfrz