toneman

On my ES, I have noticed that--with a full tank of gas, or close to it--when I accelerating from a stop, there is a dull but audible clunk emanating from the rear of the vehicle. By "accelerating", I don't mean take off like you're trying to set an all-time best 0-60 mark, but not exactly take off like a granny either; medium to moderately firm and quick application of the gas pedal is all that's needed for me to reproduce the clunk. The funny thing is that the clunk is all but non-existant once the gas tank reads around half-full or less; also, another ES 350 w/ a full tank that I test-drove w/ the service tech exhibited the same problem. Of course, since this other ES exhibited the same "issue", the service tech "wrote it off" as acceptable/normal...go figure.

Have any of you folks noticed a similar issue w/ your ES 350s?

dunnojack

i talked about it in one of my numerous other threads.

It sounds like the spare tire hitting the compartment right? <--- That's the image i get when i take off from a red light.

try removing the spare tire and then test drive it. I'm too lazy to do it myself.

07LexusGuy

I haven't noticed this myself until you mentioned it. But I just thought the spare tire is held down by that really long stick with the screw thing on the end (what's it called? I dunno). Anyways, the tire is really quite heavy and I'd suspect it'd take a lot of force to make it move since it is rubber and the floor of the spare tire well is groved so as to provide quite a bit of traction to hold back a heavy rubber tire from sliding across it.

I'm not saying a spare tire moving around is out of the question - it just seems like there may be something else if the sound is present only during times when there's at least a half tank of gas or more. Fuel level shouldn't make the tire move around

dunnojack

makes me wonder too.

i looked at the spare tire today, and it looks secured in there alright.

What if the gas tank was loose and banging around back there...

Jonathann

Yes....I have noticed the same exact clunk but thought that it had dissipated. Now that I think about it, it definitely does seem to be more audible with a full tank of gas; especially with a slight acceleration. I haven't complained about it because I didn't think it compared with the transmission issues that haven't been resolved, so I figured why bother. Good to hear I am not crazy and wasn't just being too picky.

NGG

Gasoline surge in poorly designed baffled gas tank? Who knows. Just more of prematurely released design/engineering and insufficiently tested issues on this 07 model. Yes, I know I will take shots on this comment, but it is indicative of the other reported "unLexus" issues surrounding the release of this model. So be it.

Before the dissenters chime in, for the record, I strongly believe that Lexus engineering and quality control is superior in general compared to other manufacturers. I have owned eight Toyota/Lexus products and currently have a special order IS350 to replace my surprisingly "Lemonlike Lexus" ES350. I am partial to the brand, but call it like it is with respect to this '07 model, both from my experience and what is reported on this forum. I make no apologies for this opinion and I am happy and encouraged that many ES 350 owners are completely satisfied with their cars. That is as it should be. Unfortunately it is not universal!

2007es350

Right on! The gas thunk is the least of my concerns. My slipping transmission is much more troublesome. Although, it would be nice of Lexus to fix the gas tank thunk at some point.

dunnojack

you should Never be afraid to point fingers and state your opinion. let the extremist fanboys bring it.



me too. it's way at the bottom of the list. but it does spark a tad bit of curiosity.

ES350Bob

Up to now with this thread and dunno's casual mention of it on the other thread, I was thinking the thud I'm hearing is the as yet unwrapped cargo mat back in my trunk. I also hear this at times when having to brake hard to a stop.

I'll remove or install the cargo mat and let you know if that is what it was in my car next time I add fuel.

glock22x

hrmmm I always thought it was the spare tire too.... One time I thought someone lightly rear-ended me

toneman

Just to make things clear--in no way was I insinuating that the rear clunk issue was a more critical one when compared to the tranny issue; I was just offering up another possible "problem" to add to the laundry list of ES 350 problems. However...FWIW if the clunk is due to a poorly-mounted (for lack of a better description) fuel tank...this issue could possibly be construed as being just as serious an issue as the tranny one.

Addressing the clunk itself--I guess I could remove the spare tire but as others have pointed out, that sucker is bolted down securely; the tech even checked to see if there were any loose things in back that could possibly cause the clunk. Even if it were a loose spare tire...why would the clunk all but disappear (or at least not be audible to my ears) when the gas is around half-full (or half-empty, for you half-full/half-empty glass folks ) or less?

NGG's post was interesting in that he mentioned about a baffled fuel tank; that was more or less what the tech was suggesting. Not knowing a whole lot about the purpose of a baffled tank, I could not help but think how/why a full tank could possibly slosh around inside a tank so as to make a clunking noise (I'm just speculating here, not saying that that is indeed what is causing the clunking), but yet there is no clunking w/ a half-full or less tank.

Here's my hare-brained theory as to why the clunking occurs only with a (near) full tank of gas: I'm guessing that one (or more) of the fuel tank mounts is not bolted securely in place...so when the tank--which is full of gas--shifts upon acceleration, it is hitting against something. That the clunk is (more) audible w/ a full tank of gas is somewhat akin to the level/type of sound that is made if you threw a heavy rock at a wall vs. throwing a very light one against the wall (both thrown at a somewhat low but identical speed)--the heavy rock thrown at a somewhat-slow speed against the wall will make a dull but clearly audible thunk...whereas the light rock thrown at the wall at the same speed may not make much of a audible thunk at all...and almost definitely not a loud dull clunk.

So...is my theory "way out there"...or should I insist that the service tech really figure out what's causing the clunk...especially give that my recently-deceased POS '94 Nissan Sentra doesn't exhibit that same kind of symptom?

ES350Bob

Tony,

If you are willing to be the test subject for the cause, then please be it.

I agree with you that a loose fuel tank fitting would be just as serious as a tranny issue.

I will never assume anything again about any vehicle, I assumed thumps back there were my unwrapped cargo mat, so I am interested to know what you find about your own car as to this thump noise.

ESsearch

It is possible it has nothing to do with the tank itself. Don't forget a full tank of gas adds about 115 pounds to the rear of the car which will alter the ride height a bit and load the springs and shocks a bit more. Anyone notice the clunk with rear seat passengers or other weight in the trunk?

Pete

dunnojack

it's def not the mat. i've always had my mat laid out.




that's for lexus to try to figure out, hopefully. we just throw out the questions, they should come up with the answers.



It is defintely a new experience with this ES. many new problems that have never ever appeared in my older cars.

sarge43

Talked to a service tech. about this issue and he stated that this is due to the float in the gas tank hitting the top of the tank. When the fuel level goes down, there's more room in the tank for the float to move and not touch the top of the tank. He described it as 'normal' and not a safety issue and definitely not a moving or loose fuel tank.