Dealer said high pitch sound was normal. Advice needed.

[prestigious-iceberg77]

I own a 2018 Toyota 4Runner that has around 59,000 miles on it, and I've begun to hear a high pitched sound when I slow down particularly on colder days. The sound becomes more noticeable when maintaining speeds between 60-70 mph and seems to worsen when driving on an incline or decline. Interestingly, the pitch doesn't change when shifting into neutral or switching into 4WD, which makes me wonder if it's truly tied to the front differential. The differential was replaced at 53,000 miles, and while the dealership insists the noise is normal, I'm not entirely convinced especially since the whine persists. My factory warranty is expired. I've got a week left on my purchase warranty, so I'm on a tight timeline to figure this out.

Could this issue be related to the transmission or perhaps another driveline component rather than the differential? Has anyone encountered this kind of noise under similar conditions? I'm trying to narrow this down step by step and would appreciate any insights or advice.

 

[SeaBreeze]

It could be many things, like the wheel bearings, a bad gearbox, or maybe a loose piece of plastic under the car. Try to check if it does it at other gears at high rpm and all, also make sure the alignment is good and not the tires

 

[prestigious-iceberg77]

It could be many things, like the wheel bearings, a bad gearbox, or maybe a loose piece of plastic under the car. Try to check if it does it at other gears at high rpm and all, also make sure the alignment is good and not the tires

Good points! I'll definitely check the wheel bearings and gearbox, as those could be key suspects. Loose plastic hadn't crossed my mind, but it's worth a look. Testing at high RPM in different gears sounds like a smart way to rule things out step by step. Appreciate the insight! Let's hope it's nothing too tricky to fix.

 

[RoadRunner]

I own a 2018 Toyota 4Runner that has around 59,000 miles on it, and I've begun to hear a high pitched sound when I slow down particularly on colder days. The sound becomes more noticeable when maintaining speeds between 60-70 mph and seems to worsen when driving on an incline or decline. Interestingly, the pitch doesn't change when shifting into neutral or switching into 4WD, which makes me wonder if it's truly tied to the front differential. The differential was replaced at 53,000 miles, and while the dealership insists the noise is normal, I'm not entirely convinced especially since the whine persists. My factory warranty is expired. I've got a week left on my purchase warranty, so I'm on a tight timeline to figure this out.

Could this issue be related to the transmission or perhaps another driveline component rather than the differential? Has anyone encountered this kind of noise under similar conditions? I'm trying to narrow this down step by step and would appreciate any insights or advice.

This sound could be coming from the transmission, transfer case, or yeah the wheel bearings. Any update on this? Did you get to check what @SeaBreeze want checked?

 

[prestigious-iceberg77]

Pretty accurate @SeaBreeze @RoadRunner

Since the warranty lapsed before I could act, I took it to a trusted mechanic that a friend recommended for a 2nd opinion. They started by inspecting the driveline components, transfer case and transmission and checking fluid levels and conditions.

They found that the transfer case fluid was slightly low and showed signs of contamination. This could explain the high pitched whine mainly under load or on inclines/declines. The mechanic flushed and refilled the transfer case fluid and also noticed some wear on a wheel bearing during the inspection which they think contributed to the noise.

So far the whining has significantly decreased, though I'll keep an eye (and ear) out to ensure it's fully resolved. It's a relief to finally have some answers even if I missed the warranty window.