If this nut came loose, what do you think the resulting symptoms would be? Could it result in a catastrophic failure of some kind? Vibration/noise? Before I tear apart my car to check it I'd like some opinions.





flange nut

 

You'd have a leak and that's about it. There wouldn't really be any noise because the driveline doesn't have much room to move back and forth. Why are you concerned about the nut coming loose?

 

Been beating my brain in for three years trying to figure out what's been causing a rattle noise in my car. Have started a few threads on here about it and replaced/checked/serviced many items without any success.

https://www.clublexus.com/forums/mai...g-me-nuts.html

https://www.clublexus.com/forums/ls4...e-stumped.html

 

Transmission?

 

Sure hope not. Replacing all the trans fluid had no effect on the noise, and there were no abnormalities with the old fluid. The car drives and shifts fine. I figured a transmission issue would have manifested into a huge problem long ago.

 

Just read through all the posts on this problem... Wow... This one has me stumped. I watched the 2 videos and I really don't hear the noise all that well, but then again, I'm watching it on my computer at work, and all it has is a small internal speaker. I'll have to listen again tonight when I get home...

So, just to recap for us
1) New cats
2)new gaskets for exhaust
3) no noises in the rear diff?
4) no transmission noises audiable?
5) does it do it when you're using the Cruise Control?
6) Rear Half Shafts are ok?

I'll keep thinking about it...

 

1)yes new cats and y-pipe
2)yes new gaskets
3)none that I can tell, none reported by techs, had gear oil changed as scheduled
4)none audible from outside of vehicle, none reported by techs, shifts fine, fluid fine
5)yes
6)as far as I can tell, no issues reported by techs

Multiple techs have tried to diagnose this noise and either they A) can't hear it or B) said it's the cats or that I need to run a fuel system cleaner through it or they just shake their heads.

The videos I recorded from inside the car are difficult to hear, I've found they are most clear with playing on my iphone, not my laptop. The youtube video of the car with a bad catalytic converter is very clear and the noise is exactly the same as mine. Sounds like jingling keys or something.

 

Dumb question, but is anything possibly stuck inside the exhaust pipe, or maybe inside the muffler/resonator??
We're really running out of possibilities here....

You stated that it's been making this noise for 3+ years now. When did you first notice it? what had most recently been done to the car before the noise first appeared??

We'll get it figured out...

 

Not a dumb question, thought about it myself. Everything forward of the resonator assembly is new with the exception of the exhaust manifolds, and I've looked into the resonator assembly with a flashlight and couldn't see anything abnormal. Rubber mallet and stethoscope sounds solid on everything, including manifold heat shields. Even got on my back with a stethoscope while the car was running through rpm's on a dyno and couldn't detect anything.

The noise came on gradually and has since gotten louder and more noticeable in the past year. The car has had all it's normal maintenance, it has 158k miles. Since then all front suspension parts have been replaced, air shocks, steering bushings, tie rods, exhaust y-pipe, cats, a/c compressor, alternator, tensioner, idler pulley, water pump, belts, starter. Driveshaft center support bearing went bad over a year ago and I had that replaced. The ONLY time there was an abatement of the noise was when I had the motor mounts replaced soon after that driveshaft bearing. I thought I had solved the problem but the noise slowly re-appeared over the following few weeks. I just had both oil control timing tubes in the VVT system replaced because they were leaking oil, which my two main techs both said is unheard of on the LS430. They also put in a new timing belt, front crank seal, cam seals, spark plug seal tubes and seals while they were in there. They couldn't find anything else wrong with the car. Only CEL code I've ever seen is a recent evap/charcoal canister code, which the tech reset and hasn't reappeared since then, which was five weeks ago.

When the sound is loud, I can lean over and put my head down by the shifter and it sure sounds like its coming from right there in the transmission tunnel. Doesn't sound like it's coming from behind me at all. If I put the car in park or neutral and rev the motor it sounds great, smooth and quiet, no noise. I notice the noise at almost all speeds now, and during acceleration and deceleration, but it really amplifies when my foot is very lightly touching the throttle at high speeds.

My brother in AZ has an '01 with 235k miles, his car developed the same noise a while ago, albeit it wasn't as loud. He had his motor mounts replaced and has not heard the noise since. I gotta believe this is a common problem, but I'm feeling isolated since it's gone so long and I've had so many techs try to solve it with no luck. Absolutely baffling.

 

About the mounts... Are they OEM? Is it possible they are transmitting drivetrain noise through the body? Perhaps one or both failed or are loose for some odd reason??

I'm grabbing at straws here...

I'm assuming the rear mount has been replaced as well?

 

OEM mounts, all three are new. I looked at them and didn't see anything loose. Engine idles and runs smoothly so I don't suspect an issue with the mounts.

 

With the noise all the time, and when your foot is lightly on the pedal, tells me that the noise is most prevalent under a light engine load.
I had a truck years ago that had a 4 speed transmission, and the gears had been worked on, but not set up correctly. The "Back Lash" was not correct, so the meshing of the gears was happening on the wrong section of the gear tooth face. Quiet during heavy acceleration, but cruising, or decelerating caused an annoying noise. However it was more of a whine that keys jingling...

 

We talked last year sometime. My 02 LS has the same noise and it has progressively gotten worse over the last couple months. I was getting ready to replace cats but have not done that because I was not convinced that was the cause.

Is there anything in the muffler that could cause this sound and it could travel to the front of the vehicle?

I can pretty much make this noise happen on command now. Almost like something is "tinking" one direction when I light press the pedal and then "tinking" the other direction when the pedal is released. Then if I feather the pedal it sounds like keys jingling.

MOST FRUSTRATING THING!!! A 60k car should not develop something like this and no one be able to figure it out!

 

I seriously doubt the rear mufflers could be the source, and I don't even think the resonator assembly is either. I've checked both of these a few times and can't find anything loose inside them, and they're both in fairly good condition.

I will be taking a second look at my driveshaft soon, maybe there is something that I overlooked.

 

Catalytic converters can sometimes break and the pieces rattle around inside, I've had that happen to a different vehicle. Makes a rattling noise like some gravel in a coffee can.

There's 3 catalytic converters on the LS, there's one that joins the Y-pipe near the middle of the car and two that are closer to the engine that come right off the manifolds.

If you can easily hear the rattle inside the car , I would think any decent shop that can throw the car on a lift would be able to track it down.