Kaius88

oh. That actually makes sense. He better be telling the truth. I noticed my thud also...and always thought it was my gym shoes hitting the side of the trunk. Anyway thats real informative.

BobBass

Gee, I wonder if this "feature" is included on the GS & LS sedans.

Maybe Lexus put it there as an aural indicator of a Fairly Full Fuel tank.

toneman

Although I applaud service techs that can offer an explanation that seems valid, writing it off as being "normal" is just a copout for saying that nothing will be done to alleviate the concern. "Normal", my a**--I've driven other sedans...especially ones that are lesser in build quality than those offered by luxury makes such as Lexus...and I've never heard similar clunks that would be attributed to a float hitting the gas tank. I'm not saying that ALL other vehicles don't have this issue, but clearly there are quite a few that don't have it...and it's not necessarily just limited to fancy expensive vehicles. Heck--my POS '04 Nissan Sentra never exhibited this clunk...does that make my car NOT normal because it doesn't have it? Or what if my ES didn't have the clunk--should I go have the tech make it clunk so that it can be "normal" like all the other ESs that have this "normal" clunk?

For those folks who feel that, given the above explanation, this clunk issue isn't a big deal...try telling that to those of us who are saddled w/ wind noise (or creaks and/or rattles from the dash/windshield/rear deck areas); after all, wind noise is definitely not a safety issue (especially since, unlike the gas tank float issue, there is nothing solid hitting the car itself)...yet there are plenty of anecdotes from other ES owners in this thread who are clearly not happy about having to accept wind noise as being "normal" for our vehicles.

Or put it this way--why would someone accept driving a vehicle such as a Lexus, that is devoid of wind noise and/or rattles but not devoid of other annoying noises like gas tank float clunks?

dunnojack

What's the float made of and how big is it i wonder....
sounds pretty loud

ES350Bob

Took the rolled up cargo mat out, filled up the car this afternoon--to just over 7/8 tank. And that is no float clunking back there or it is one mother of a float.

I think it's the brakes letting go back there, I seem to remember reading there are times when the brakes, one side anyway, can make a thump noise when releasing and there is a TSIB for it I think for some adjustment.

Maybe the increased weight of having added that volume of gas aggravates it???

Otherwise Tony, you have to be the test subject and get it looked into and report to us.

toneman

Nice theory, except...what if the clunk is still there even after the brakes have been released for a second or two--like if I wait a second after having taken my foot off the brake pedal, before hitting the gas pedal? Regardless, your theory is still a viable possibility, and one that I will offer to the tech if he still tells me that the clunk is "normal/acceptable", just because other ES 350s exhibit the same issue.

ES350Bob

Tony,

I don't think it's normal in the sense we should hear this, maybe it is wishful thinking on my part to view it a minor brake adjustment required rather than what it might be as to your concern. A brake adjustment is less concerning to me than to think something moves with the gas tank.

I appreciate your willingness to go be the test subject, it will benefit us all whether you find out for us it is brakes or gas tank attachments.

osokuko

I was curious about the location of the fuel tank and found it was mounted under the rear passenger seat forward of the rear wheels. How does the float sound travel to the rear of the car?

ES350Bob

Well, if that is where it is located...

....then Houston we may have a problem

dunnojack

What would be awesome is if there could be open chat with lexus engineers and designers.
Like one hour a week would be nice. Ask them all the questions in the world, like this clunk.

toneman

ES350Bob--thanks...I will definitely have the tech do some more meaningful research into the clunk--in addition to performing whatever TSBs my car is suffering from--when I bring my car in for the free 5K oil change.

Like I said in my last post--I can't see how anyone could possible live with being told that any kind of clunk-like noise in their vehicle should be considered normal...regardless of whether or not it occurs in other vehicles.

sarge43

The sound being in the rear of the car is meant to indicate that it comes from that direction when heard from the driver's seat. The sound does not come from the rear bumper area nor from the wheel wells. It actually sounds like it's behind the rear seatback.


As you can hear it when you apply the brakes suddenly (not slamming them though) while backing up it does not involve the 'release of the brakes'.

pfrosen

I've been dealing with this and as far as I'm concerned it is not normal and it is unacceptable. I plan to as far as arbitration.

ChipM

I'm having a similar problem on an RX330. I seem to recall a noise like this with newer BMW's being ralated to pressurization of the fuel tank/fuel system (on OBD-II cars, i.e. post '96, the fuel system is pressurized in order to be able to detect leaks. This is also why you get a CE light for not tightening the gas cap). So, i think it has something to do with suction collapsing the gas tank, and the "POP" is the tank opening back up when suction is released.

What i can't remember is why there is too much suction, and how to fix it.

mmrfr

With Lexus, any problem is a normal charactristic. Maybe a sales decline similar to Fords or GM's might be just a normal business condition. Wake up Lexus before your customers do!!!!