IS350 grinding noise when taking off
 

2006 Lexus IS350 225K
On Coils and Wheels

Hey guys, so over the past two months, I have had this grinding noise when leaving my driveway, and it almost sounds as if there is a metal on metal contact when taking off. I notice it almost every time I leave for work or go somewhere. It usually happens during a cold start, but after a while I took some notes on things that could eventually bring me to the symptom. Please let me know if anyone else has had the same problem

Notes:
- Usually during cold start and taking off there is a grinding noise towards the front of the car
- Checked all contact with my tire/rims to fender, which has no contact or interference what so ever
- Calipers have no contact to rim, therefore that is not in the equation
- Checked the fan in the front, no contact
- Belt seems to run smoothly, although I do have suspicion it could be a pulley or something especially since I have had a continuous squeaking belt issue after long drives or humid days.
- Transmission appears to run smoothly, although I hear a quick grinding noise around 1st to second at odd times
- Grinding does not happen on idle, only when holding throttle or accelerating

I honestly checked everywhere on my car from eye level to it being jacked it, to see if there is anything that is making contact to moving parts. Although there is no luck, it always catches me off guard when I am driving or taking off. Please let me know if anyone has had a similiar issue!

cam gear rattle?

Have you checked your oil level?

I just changed my oil to 6.6-7 qtz to this week to make sure it wasn't any rattling, but that hasn't done anything.

I hope that is not the case, but I don't know how to diagnose that to be honest.

What speed, what gear, what rpm? Does it matter?
Does it do it in reverse? What if you powerbrake it? Like 1800 RPM foot hard on brake. Does it do it then?

Can you record it? If not, please give more details about the sound to help us focus.

GL

What about if you just rev it in neutral also?

Haven't tried revving it in neutral, I'll get back to you on that one.

I did record it, here's a link. I took my heat-shield off both of my cats since they made rattling sounds like this one, even sat under my car on park to see if my exhaust rattles on idle...nothing. It usually rattles when accelerating and climbing the revs from 1-5k, weirdly enough it makes rattles at non-specific intervals which makes me really question it. It sometimes does it in reverse as well.

Keep in mind I also replaced my serpentine belt and oil. Also moved all my pulleys to see if there was a grinding or poor pulley, but no results. Checked under my car for any contact with the exhaust and/or anything else, no answer too.

Heres a timestamp of the noise when driving it, (11 seconds, 45-46 seconds, 01:09 seconds, 02:09 seconds, good clear sound at 02:23, faint sound at 03:27, 03:33, 03:49, 04:02, 04:49)

​​​​​​​

Caught a louder sound from when I put my car on park today.
https://youtube.com/shorts/puZTI_MEDHE?feature=share

I found an answer to the sound. It had to do with my left CAT heatshield and also the crown that was on my downstream o2 sensors after my cats. The both appeared to be loose, just tightened the o2 sensor and removed the heat shield and boom.

The 2023-08-09 video sounds like exhaust rattle but more concerning is that the engine doesn't accelerate smooth. Does it shake at an idle? It may be starting to carbon up. Glad you found it.

What do you think I should do, throttle body cleaning, anything else? I have a catch can to try to avoid any problems, but I notice that it does kind of shake during idle. Thanks btw!