08 RX350 213k miles.

Did a bunch of work (alternator, valve cover both banks, ATF drain+fill+filter, transfer case, rear diff drain + fill) Has a light whine on load (applying accelerator) at low speeds (~15-25mph). Sounds like transfer case region (from under the center console) Not present at high speeds but of course could just be drowned out by higher wind/road noises. I don't recall the noise was there before all the above work but not my car so can't be certain (I'm the type with HVAC+radio always off and notice every little new noise haha). But fairly easy noticeable whine for me so I'm guessing it's not placebo. Driver is young 20s female that doesn't notice anything + HVAC + radio always on. Wonder if I've overfilled transfer case and that might be the cause?

- had front end up on jack stands (front tires maybe 2" off ground max when pulled) Rear tires on floor
- 0.7L came out transfer case, stopped filling at 0.9L in (didn't drip from fill hole) drain plug and drained oil was clean.
- Supertech 75-90 synth (GL-5 compatible with hypoid)
- Transmission drain+fill+filter with Toyota WS. 5.75qt out, 5.1qt in. ATF level checked multiple times (and after test drive + shift though all gears) with car leveled and engine idling. dipstick between 2 hot marks.
- Rev the engine in park and no noise so maybe that rules out everything on the serpentine belt (alternator etc)
- No wetness in the area even after couple of hundred miles.

Since car was not leveled and transfer case has a long nose towards the rear, wonder if 0.7L drain was due to oil left in that long nose (don't know if long noise has oil in it or sealed off from the gear/fluid chamber) and 0.9L fill ended up at 1.1L. I suppose I can pull the fill plug with car leveled and check. Will have car in a couple of days and report back on fill level. I know Supertech not premium brand but seem unlikely thats the cause? (have Pennzoil 80w-90 non synth GL5 at nearby store so maybe I'll try that if pulling fill plug with car leveled don't help)

Any thoughts welcomed. Thanks.

 

The tail section of the t-case does contain fluid. It has an oil seal and oil will pour out like crazy if you remove the driveshaft yoke from it. I had my car about 2" off the ground like you when I filled my t-case and I put in about 1l of 75W90 GL-5 (Redline NS). Both my 2002 Highlander (Mobil 1 75W90) and 2008 RX350 both have the same transfer case, and in both cases the cars were not level, but fluid still poured out the top when I pulled the fill plug first before pulling the drains. No whining after. These t-cases are super tough and they'll basically run on tar! My RX had like 0.4l of burned nasty oil in it when I drained it!

Do you have a video of the noise?

 

Thanks for the reference on lifted front end tilted fluid change and the diagram. Very helpful. I'll try to get an audio in a few days when I see the car next and follow up. Maybe I'll pump in the remaining 0.1L to start... can't imagine making any difference. Followed by switching to Pennzoil 80w-90 GL5. My impression (could be wrong) is the fluid that came out looked clean and was thicker than the 75W-90 synth GL5 that went in (Supertech viscosity felt similar to the valvoline synth I pumped into the rear diff). No longer have original fluids to compare

 

Could be T-case, check the carrier bearings for the driveshaft as well. When I developed a whine under the center console it was from a bad bearing in one of the support carriers for the driveshaft.

 

Saw the RX today and recorded the sound. Used my Phone 11 voice memo and pointed the screen towards passenger foot well area while driving so slight right of the tunnel. And worked with AI to determine the frequency and a band filter to better isolate the sound

• Sahalee Dr E.m4a is the original recorded sound (just street name) m4a is common macOS sound format but can't upload as attachment here.
• Sahalee Dr E.mp3 is the converted mp3 version more commonly used on other OS
• whine_isolated_wider.wav is isolating 250-550Hz. 10MB file so I didn't upload it
• whine_isolated_wider.mp3 is the compressed version of wav file
• Higher pitch whine frequency.pdf is working with Claude AI to isolate the sound frequency.

The sound is most prominent at 30s 34s 48s 1:05s 1:31s
Sound only occurs on load. Light load is best because lower engine noise interference.

 

Does kinda sound like my friend's 2004 Highlander with bad rear diff bearings, from the PO running the diff dry due to a leak. Hopefully not the bearings in the t-case, as it's a total bear to take out of the car! (Trans has to come out).

 

Sounds closer towards center console than rear but of course difficult to pin point these without all 4 tires off the ground and spinning. Does this car's traction control prevent spinning all 4 tires off the ground or can be turned off? But am always nervous whenever spin tires up in the air in home garage... But I suppose no different than a garage up on 2 post lift other than I'm under the car haha.

Since I noticed the whine, perhaps try to put thicker GL5 back into the transfer case and see.

 

I was able to spin all four of my wheels when I had the car on my friend's lift, I don't think the car knows it's in the air and just lets you do it. There is a traction control off button down near the lower dash on right side (near TPMS reset), but it still will cut power if you're cornering hard enough to upset the angle and G sensor