Low Hum. Help!

Reply Subscribe

Thread Tools

Search this Thread

Mar 17, 2009 | 11:15 AM

1111art

Thread Starter

Driver School Candidate

Joined: Jan 2009

Posts: 34

Likes: 1

From: WA

Low Hum. Help!

'02 65K miles.

Extremely low frequency nearly subsonic hum. Imagine a 40' giant humming a single low note. I have very sensitive ears and it's really bugging me. Only audible at idle with tranny in gear. When I put it in neutral, sound is gone.

Just had transmission flushed (2nd time in a year). Tranny works perfectly otherwise.

Could this be just a resonant sound from something else?

Any ideas will be welcome.

thanks in advance.

Mar 18, 2009 | 07:08 AM

lexus114

Lexus Champion

Joined: Aug 2007

Posts: 4,507

Likes: 38

From: Bethlehem Twsp. Pennsylvania

i wonder if when in gear,maybe its something in the exhaust system doing it some how.of course with these trannies,i would believe anything.

Mar 18, 2009 | 07:23 AM

carguy07

Lexus Champion

Joined: Nov 2005

Posts: 2,110

Likes: 77

From: OH

I started noticing that on mine too (2001 with 65K). It sounds like a truck is idling behind you. I can't find any easy things like an exhaust leak. I'm thinking it is just a resonate sound from the exhaust system. The damper weight thing on my exhaust fell off a while back, maybe that sound is what it is supposed to suppress? Do you have the original exhaust system with the weight still in place?

This is the weight: https://www.clublexus.com/forums/rx-...t-is-this.html

Last edited by carguy07; Mar 18, 2009 at 07:28 AM.

Mar 18, 2009 | 10:59 AM

1111art

Thread Starter

Driver School Candidate

Joined: Jan 2009

Posts: 34

Likes: 1

From: WA

Thanks for the info. You guys are great. I'll took a look under the car, and noticed the weight you discuss. It looks brand new. I hit things, I pushed things, nothing seems amiss. I couldn't get the sound to happen.

I also noticed that it only happens in 'D', no other gear, and not every single time I'm idling either, maybe 80% of the time. A truck is idling behind you- good description.

Any other ideas?

Mar 18, 2009 | 11:10 AM

Lexmex

CL Community Team

Joined: Apr 2004

Posts: 17,329

Likes: 210

From: Miami, Florida

I'd have someone sit in the car with the vehicle in D and their foot on the brake and see if you can isolate the hum.

There could be a tiny exhaust leak somewhere that could be affecting the tone somewhat. I know when I have had such leaks before (no matter where they were on the piping) that it would change the tone slightly after the leaks were sealed up.

Usually the resonator (the fat muffler underneath the vehicle) is where the sound will turn into a hum and it won't be audible from the muffler.

Mar 19, 2009 | 06:33 AM

lexus114

Lexus Champion

Joined: Aug 2007

Posts: 4,507

Likes: 38

From: Bethlehem Twsp. Pennsylvania

yep,just as our humble forum moderator suggested

Mar 20, 2009 | 02:30 PM

code58

Lexus Champion

Joined: Feb 2008

Posts: 1,709

Likes: 16

From: Ca.

Quote:

Originally Posted by 1111art

Resonance hums are a bugger to pin down sometimes, especially in the exhaust system- the reason you so often find the factory engineers keep a huge stock of weights to attach or weld on here or there to "fix" the problem. I would guess half or more of all vehicles have them SOMEWHERE on the vehicle for just that reason. My wife's '02 Camry has just such a sound that has developed but under slightly different conditions. I have tried to find it because noises of ANY KIND bug me, but with the vehicle sitting still even with someone inside on the controls, it is difficult to duplicate the exact conditions under which it makes the relatively minor sound. I will probably ignore it until (and unless) it gets worse. It is more than likely in the cat that's on the outlet of the exhaust manifold. I find NOTHING loose at all!