TLX2015

As heard here in my video, the noise will persist up to and beyond 70mph, starts at about 20 mph under light acceleration. Whether or not the A/C or vent is on (and only heard while foot on accelerator, not while at a stop or slowing down). If I take my foot off the accelerator, it stops. Any ideas what it could be? No dashboard lights appear and No Codes are found when scanned (at least with an O'Reilly auto parts scanner). I changed my winter tires and put smoother Michelin Primacy tires on and that made no change other than easier to hear this rattling noise. Link to maintenance records (although some summarized further found below). I haven't used a mechanic's stethoscope yet but looking for one currently to try. I only use 93 grade gas mostly from BP or Shell and all maintenance is current at 165,900 miles, except it is now due for a cooling system flush.

Some suggested the serpentine belt tensioner...I replaced it and the serpentine belt yesterday but the sound has not changed at all since that repair.

My thought process of what the underlying cause might possibly be:

*Front, side, or transmission mounts? No current signs of leaking or physical damage that I can see for front & side mounts
*Harmonic Balancer?
*Catalytic Converter?
*Pulley needs adjusting or bearings worn out? Keep in mind the noise continued after new serpentine belt and tensioner.
*Alternator, alternator pulley, bearings or alternator itself
*Suspension noise - something rubbing or oscillating
*Midship bearing aka carrier bearing (I read about this its new to me)
*Transmission issue? Although no harsh or jerky shifts appreciated at this time.
*Valves Need Adjusted?
*Water Pump (even though car not overheating or waivering a bit from its usual temperature aka just below half on the gauge).

Some maintenance items and complete maintenance record since I took ownership at 52,800 miles can be found at this link, no login required.


A little more background of when I first noticed the noise if this is helpful:

I first started hearing this sound after the power steering pump was rebuilt by an acura dealer. I was out of town in Las Vegas and drove 90 miles back to the acura dealer upon their instruction and they said all belts were fine with appropriate tension and checked the torque on the pulleys.

[Not sure if this is relevant but when the P.S. Pump was rebuilt also had a rear left side wheel's caliper pin found to be broken and the caliper was seized to the rotor and the dealer put on new rotors and new pads and a new pin but said the calipers were fine. Brake fluid service performed too. Front brakes and remachined rotors last done at 145,247 miles (so roughly 20,000 miles ago but checked out during acura's inspection at the time of the above repairs.] I did recently move in August 2013 from Las Vegas (no snow or salt) back to Chicago after 5 years in Vegas and the winter was the WORST I experienced in 30+ years there and the car was outside most of the time in the Chicago suburbs but the engine block heater was plugged in.

Other maintenance to note if you did not click the link for the complete record:
*Serpentine Belt and Serpentine tensioner both OEM at 165,881 miles
*Power Steering Belt Replaced at 145,247 miles
*Compressor Belt Replaced at 145,247 miles
*Timing Belt Replaced at 145,247 miles and timing belt tensioner and seals also replaced. The water pump was inspected when the timing belt was changed and was apparently fine so they did not replace it.
*Alternator Belt Tensioner replaced at 95,000 miles.
*Fuel System Cleaned by Acura at 133,000 miles.
*Transmission Replaced (with rebuilt one for the same vehicle) at 114,000 miles
*Spark plugs replaced at 133,000 miles

*The suspension (struts, sway bars, bushings, etc are still original, mostly use vehicle as a highway car. Acura senior technician said since if suspension/struts are not making noise or leaking, no need to replace the struts etc...not sure I agree with that, I thought every 50,000 miles you replaced them to ensure good contact with the road).

Thank you all in advance for any advice, thoughts, cost effective investigative techniques.

TLX2015

Well after plenty of time getting dirty and a nauseating amount of online 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 specifically when I have the time and I can catch him coming in so I can butter him up with some coffee for another moment of his time about what he specifically he evaluated on my differential diagnosis list 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.