Hey there guys. Just a quick question. I just picked up a new 2021 IS350 F sport. So far I'm really liking it. One thing I noticed however is that at idle I hear kind of a low oscillating knocking type sound from the engine bay. Doesn't sound like actual knock, but it's hard to describe. I can hear it sometimes in the cabin as well if I'm at a light with the radio off etc. at idle. It's hard to explain the noise as it's not the usual valve train noise or DI noise I don't think. Below is a link to a video of the noise I'm speaking of. Does this idle sound normal to you? Any insight would be greatly appreciated.

 

I sort of hear 2 types of noise on the video. The more higher pitched kinda ticking is normal and I have that on mine as with my previous Lexus'. The other one, I must admit I never heard

 

Thats the noise I'm talking about. Not the higher pitched ticking, but the lower pitch noise.

 

I’m not sure what the sound could be, but maybe I can help others hear what you’re hearing. I don’t hear rod knock so that’s a good start!

I hear a rumble that sounds like the washer/dryer is running in the other room. Kinda of a low pitched hollow thump. I’m not sure if that’s what you mean? Try to post videos taken from different angles, directly over and under the engine bay. That could help isolate the sound.

 

Is that lower end noise that pronounced IRL? Does it get faster with revs? Hard to say. It doesn't sound normal. but i mean it is a new car under warranty so i wouldn't stress. Maybe take it in and have the foreman listen to it.

 

Yeah, it’s hat low thump. Thats kinda what it sounds like. Like a dryer running in another room. I’ll see if I can take more videos. I did notice that the sound goes away at times, but not sure under what conditions.

 

I mean I can hear it inside the cabin when it happens, if it’s quiet enough inside the cabin. Seems to go away with revs, that or I can’t hear it.

Also, there are times when the sound isn’t there at idle. Like I just went to the store a little while ago, popped my hood when I got home and took another video, and the sound wasn’t there. It seems to happen intermittently.

 

2gr-fse v6 in my 350 sounds horrible at idle...loud, clunky, almost like a diesel...it’s normal. 2gr-fks engine on yours I’m not sure but likely completely normal. They sound good when ur giving them gas but I find they sound bad idling.

 

Sounds like normal to me, the engine is still breaking in too, so it may need a little time. If you are really concerned the next time you have service (5k free under scheduled maintenance), note it to them to do a diagnostic.

 

I think my 2021 IS350 might make the same noise, but not entirely sure. I'll check next time I'm out.

 

9/10 of these posts its totally normal. I havnt heard a 2021...but that doesn't sound normal. Don't stress make sure they record your "issue" in your meeting with them and give it time as they'll probably say no worries.

But if on the slim chance you have any minor issue later you have record of "I told you so".

 

I have not noticed such a sound with my 2021. On cold starts it has a butter smooth idle, no thumping sound.

 

Thanks. Let me know if you here something similar. It would be a great help.

 

Yeah it’s intermittent with mine. Like yesterday, i was out driving around for a few hours. I only noticed the noise for a little bit then it seemed to go away.

 

Interesting. I can check again today (assuming it isn't raining too much).