Hey guys I drive a 2002 Acura Tl type S 3.2L and have a low moan that sounds like it's coming from the hood when driving at high speeds. Basically the faster I go the louder it gets.

My rpms don't shoot up or anything like that. The transmission was replaced about 80,000 miles ago.

I was told it could be the spark plugs but after replacing them the sound continues.

Any help would be great!
Thanks!

Could also be a Wheel Bearing.

Definitely not a bearing its more of a moan than a rumble. And I work at a tire shop and definitely know it's not a bearing. Sounds like its from the engine

Spark plugs wouldnt cause it. Does the sound change with RPM or speed. If its RPM, its engine / mechanical. If its speed, odds are its a bearing. Bearings typically dont rumble unless they are really really shot. Bearings going will hum/ make a rhythmic drone as speeds increase and can usually be diagnosed by turning right or left while driving. The sound will increase turning putting the load on the bad bearing and reduce turning the opposite direction decreasing the load on it.

The sound definitely doesn't change or get worse when turning. But i know how a poor bearing sounds and this definitely isn't it. Plus I checked out my bearings and they're fine. The sound doesn't grow when changing rpms, but the sound gets worse the higher rpms I go.. If that makes sense.

Theres also a hum these transmissions make at high speeds which is a normal characteristic. Try using SS mode and down shift to 4th gear or put the shifter on D4 and see if it makes a difference.. louder or less

Another thing would be the half shaft bearing could be on its way.

The noise isn't a rotational noise though which leads me to believe it's not a bearing or any suspension.. And it's a tad bit higher pitched than a bad bearing.

When I drove in D4 the noise continued and didn't get louder or more quiet.

Troubleshoot: Hum Sound from the Front.

A) Does the sound change when the car is in park and you REV the Engine? (YES): Check belt tensioner (NO): Its not engine related

B) Does the sound change when the car is moving at Low to Medium Speed? (YES): Check Bearings and Axles (NO): Check Transmission and TQ

C) Does the sound change when the car is moving at Medium to High Speed? (YES): Check Bearings, Transmission and TQ (NO): Check Tires and Brakes




That's pretty much it...

ck the ac belt tensioner pulley at top of engine, by alternator
that thing is a common failure- it makes a loud rumble when really bad!

mine made a bad noise for 40kmiles before it finally quit at 85kmiles
You can rev engine and see how much the tensioner was moving -how it responds to rpm change

my usual suggestion of a `mechanics stethascope` with its pointed end for finding noises
Its the tool everyone needs- 10 bucks at parts store, 4 at harbor freight tools

Could also be loose undercarriage plastic covers.
My inner fender was detached from the front bumper but not enough to scrape the ground, that made some noise at 30mph.

did you remove the intake resonator box?

And if I am getting belt noises sounding like it's coming from the tensioner pulley, is it usually the pulley bearing or the swing arm?

replace the tensioner unit as one part= with new arm (contains spring that loses tension) and roller pulley (contains bearing that likes to fail)