zig

Hello everyone.

I bought used rx350 2007 MY (actual date is 2006.03). I have a problem with car. When i pressing gas pedal the car starts humming, as soon as i let off foot from gas pedal the humming noise is goes away. My car has All wheel drive. All wheel bearings were changed. Car has 114000 miles on it. Dealers and services can't diagnose this problem. Do you guys have any idea, what can cause the humming noise?

Thank you

sammoe

I have the exact same issue .. really need help

Margate330

You been a member a little while but I see this is your 1st post sooooooooooo Welcome to Club Lexus!

hugo2648

I want to say it is being caused by worn motor mounts.

MikesLexo

Wow I have the problem and surprise no one find the solution yet.

edlexus1

2009 with 155K miles. Near perfect in all ways. No other noises except this same sort of hum which sounds like maybe differential and or trans. Maybe all of our 4WD cars make this noise even from new? It is that sort of bad wheel bearing noise but my bearings are fine. I am guessing a worn part in trans/diff arena. Someone must know the prob and knows the fix too.

MikesLexo

Anyone figure this out ? Bought a 2008 recently and did full tune up, trans fluid and differential. 1st i thought it was something i did that caused it but seem not. Can't tell when bought due to bad decoupler from alternator causing squeals. Once that solved, now I can hear the humm only during acceleration but no hum when let go of acceleration at high speed. Everything seems normal but hummmm kills me

edlexus1

at between 20 to 30 mph with radio off and no wind noise. it goes in and out as i either coast or apply a bit of gas. prob making the noise at higher speeds too but the car runs so quiet and smooth at highway speeds i have no issue with it. at 155K miles i could guess some wear part (bearing) in the trans/diff is the culprit. not terrible just wondering the cause.

hugo2648

Have you replaced the alternator recently? In my RX, there is an alternator whine (not hum). It is an electrical noise. My RX300 still does that. I think changing to a 130 Amp Alternator will solve it for me. The one I bought from NAPA was 100Amps.

bullyboyzz

U might wanna check the alternator pulley, ac compressor or any other bearings/idler on the fan belt side. If not then it would be internal on the timing belt side

fabchef

Hmm this is interesting. As mentioned, it really is when accelerating, correct? When gas is let go, the sound goes away? Can maybe a dirty fuel injector cause this?
the bad mount idea may be a possibility... as when you accel... it causes the engine to move.

GotHeem

I posted here about my car's squeaking (not humming like what OP described) while accelerating. My mech thought it's the front and rear engine mounts as well as the tranny mount. He was right. Replaced them with PEM mounts. No more squeaking.

I also have a video here so you can hear the sound: https://www.2carpros.com/questions/c...-the-gas-pedal

fabchef

Gotheem. Wow! Interesting sound. I found it sounds more like metal grinding. Glsd you found the problem. Any issues in terms of functionality..gear shifting?

GotHeem

No issues so far. It’s only been about 200 miles since I got the mounts replaced… but so far so good. It did have a bit of hesitation at really low speeds (up to approx 12mph) a few weeks before I had the mounts replaced. That hesitation takes effort or luck to reproduce so I’m not too concerned about it… just have my eyes and ears on it for now.

fabchef

Hmmm ok? What kind of hesitation? I'm curious now. I had my tranny rebuilt last year. I notice usually when "crawling " in traffic, at around 15-20km/h...if i slowly accelerate, the revs slowly go up but car isn't really moving, then it upshifts and shifts well. If i come to a complete stop, though, and accelerate, it shifts through the gears perfectly.
off had, do you know where all the mounts are located? I can check mine out.