Only happens while foot is on the gas. Hoping a better audio sampling will help identify the underlying cause. Maintenance is current on my 2001 3.2TL, mileage 166,000, premium unleaded gas. 2nd transmission at 114,000 mi. Any thoughts to what the underlying cause of the noise is? 4 audio clips captured from under the hood are posted here. Please and thanks for any thoughts you may have. My last post was a bad attempt at soliciting advice , hoping this one will get lots more attention.

 

going to guess ac belt tensioner is failing
does it sound like a V8 engine when you rev it in park?
watch belt tensioner- located near alternator at top of engine
rev and release- turn ac on- see if belt is jumpy or steady
look for trace oily fluid from back of tensioners round part
Use a mechanics stethoscope to listen to the bearing in that part

 

Once the rain stops I'll go give this a try. I'm not sure my hearing is good enough to pick out a v8 vs a v6 from revving though, what would the v8 sound indicate? I'll share what the findings are when I can perform these. Thanks for your help 01tl4tl!

 

Wow, what some would give if they could simulate the sound of a V-8 in their TL.

 

its easy!!, simply drive about 40k miles after that tensioner starts making noise and the dealer wants a fortune,,,at 45 it begins,,,20k later the car gets belts changed then car sold (to me),
but
tech FAILS to inspect and replace tensioner then! So another 20kmiles and it finally rattles and makes noises unnatural to a good running TL

a mechanics stethoscope at harbor freight tools is under 5$ or less than 10 at any parts store
invaluable tool for tracking noises and quick ck of any bearing in motion,,rhythmic is good,,, gravel sound is bad

 

3.2- there is a setup with mics and mini speakers for any car- it takes the exhaust sounds, rpm, speed etc are run thru a computer that can CHANGE the sound you hear in the car
Want to drive an Italian screamer or a refined Bimmer or no noise at all, 8 settings last I knew a few years ago,,Imagine now!
Technology, aint it great

 

Thought there was a model year such technology would only date back to like 2013 or something unless there are other mfrs doing this besides the one showing the arse end of a blue 3 series BMW seen online in the past year? But either way that is an irrelevant tangent, no offense.

 

Could also be the half shaft bearing worn out.

 

does the noise occur only when rolling-driving the car
or then AND when at stoplight and ac comes on and off?

the sound device I saw was aftermarket on sunday tv car show a few years ago
try the internet~

 

The noise is only heard when foot is on the accelerator. The moment you take it off, it stops. When car is slowing I don't hear it nor does the digital recorder. Noise does not happen when at a stoplight (in D5, N, or Park) with or without AC. I replaced the Serpentine Belt Tensioner last night given mine had about 70k miles on it already and the Serpentine Belt itself and the noise persists just as it did before.

 

Is there an old trick to check the front,side engine, transmission mounts? They were replaced about 80-90,000 miles ago, there is no fluid leak from them or obvious physical damage, but not a repair ideally I want to embark on myself. I'm considering using Velcro and duct tape to secure my iPhone with the flash on under the hood to see if I can watch them oscillate or something when the noise occurs. Also how can I rule out the harmonic balancer as a source?

 

Replaced the tensioner and the belt like I mentioned in another post this morning but no change. Sorry if this is a redundant post, so hard to see/scroll on my phone.

 

if it only happens when in motion I would agree with the post by Erik
the half shaft or cv shaft is the driveline and known the simply wear out
or fail from curb shots etc.
Does it do it more if you whip the wheel back and forth at low speed- load the bearing?
that stethoscope will tell you instantly
put the car on jackstand and have buddy spin wheel by hand while you listen to bearing cage

inspecting front and rear engine mounts is a visual from underneath- on jackstands or ramps is best
look up at them for traces of oil leakage,,oil trail, dust in odd way on mount, and drips on garage floor point to mounts
Those 2 mounts are fluid filled and vac assisted- failure leads to mystery engine miss too

front is often the first failure, followed by pass side, then rear if those went a long time broken

pass side is visual and prybar method- its a normal rubber mount

Mechanical test- block front wheels so car cannot move!
have trusted person apply brake and shift-rev etc while you watch (from SIDE of car) for movement of more than 1/2 inch of the engine
there is a thread or seven on here about it- probably youtube as well

 

Loading the bearing does not make the sound occur (it never happens while turning but I checked again). I haven't done the mechanic's stethoscope by my mechanic did (more about that below). If I had the time and money I would consider just replacing both half shafts, although draining the tranny as part of that isn't something I've ever done nor am I sure I want to (fluid was changed about 21,000 miles ago).

Well after a nauseating amount of reading, I still could not find the source of the noise, swallowed my pride, set my ego down, pulled out my wallet, and took the car to the only shop that our family ever has used to work on cars for my 32 years in the Chicago suburbs. The two top guys in the shop acknowledged the noise but also cannot identify its underlying cause. The caveat being it could be from the transmission (cross your fingers it isn't, the rebuilt warranty just expired) but they don't touch them at their shop. Their advice was just keep driving it until it gets worse. They specifically stated the motor mounts, tranny mounts all look ok, no vac leak. I will go talk to one of the mechanics and ask what all he specifically evaluated on my differential diagnosis list (and his own) and add to this post.

To my knowledge, I don't know of the 3.2TL automatic engines to get piston slap or have a common failure of spun bearings which could produce such a sound? Maybe something happened or is loose after I used the Goodyear Winter tires this past winter. I do not think this will help but would seafoaming the car be a good idea? I'm also tempted to look at the EGR ports. Please talk me out of anything stupid like what I just mentioned! Ideally this car will last me a couple more months and then I can sell it, ideally in good mechanical condition, I don't want to make it someone else's problem but also not looking to spend a fortune if I won't get use from the repair. I've stumped quite a few people on Honda and Acura tech sites/blogs as well as heard similar noises from vehicles after lots of Youtube time...but no one seems to know exactly what the cause is and I'd love to share with anyone interested should I find the answer. That said, thanks to my audience for all of your time and thoughts regarding my car, any other suggestions are welcome and I'll be sure to post any updates if I have any about this noise. I hope its not a torque converter. Still no codes when scanned.

 

Hey TestDrive2014, considering that ya only are going to keep the car a few more months......
your family's trusted mechanics gave ya some really sound solid advice, IMO.

Why continue wasting time,money and effort to chase down these noises for the next owner ?