I have a whining humming noise i can’t figure out.
I starts about 30 mph and will continue on and get a littler higher pitched as speed increases.
Engine RPMs do not affect it, and it only happens while under load. The sound goes away if i let off the gas, and cones right back when i press it again.
I’ve changed the fluid in all three diffs: front, center and rear, with no change to the noise.
I’ve actually changed the rear twice in the past few weeks (a week ago and today). Went wheeling a few weeks ago and unfortunately got into a bunch of mud. The first time i changed the rear diff oil, it looked horrible. Like it had gotten water in it, and possibly sand, though not totally sure.
The oil in the front and center diffs looked good
I tried to take a video, and I’ll see if i can figure out how to get it posted here.
So what do you guys think? Bearings? Rear diff?
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2001 4runner SR5 v6 4x4
TBU | Toytec / Eibach 3" springs up front and Superflex rear | Bilstein 5100 front and rear
Toyo Open Country MT 305/70/16
Specialized Rockhopper Pro 29er
I'm having a somewhat similar issue except mine is not dependent on the RPM's or being under load. In my case, at around 30mph a humming noise starts picking up and gets louder up until 60 where it slowly starts fading away as I reach 80 or so. I can put the car in neutral while coasting and the sounds doesn't go away. It's definitely speed dependent. It sounds like it's coming from the front. Mine is the 2WD.
I'm having a somewhat similar issue except mine is not dependent on the RPM's or being under load. In my case, at around 30mph a humming noise starts picking up and gets louder up until 60 where it slowly starts fading away as I reach 80 or so. I can put the car in neutral while coasting and the sounds doesn't go away. It's definitely speed dependent. It sounds like it's coming from the front. Mine is the 2WD.
Start with tires see if they are worn evenly. lift up the vehicle check the brakes, turn the wheels and check for resistance noise. pull push all wheels to see if you have any kind of play. Rear wheel bearings sometimes can be miss judged as front noise. lube the drive shaft. Isolate the noise on jack stands and go from there.
Thanks for the suggestions everyone. I checked the pinion bearing by putting the car in neutral and there was no play whatsoever. I'll be greasing the u-joints and drive shafts today along with checking the rear diff fluid and changing it out if needed. I'll keep looking into it and keep you all posted if I run out of ideas. Thanks!
So here's a quick update on a quick visual inspection today. Other than checking the pinion bearing a few days ago, I noticed that the tires on the right side of the vehicle have uneven tread wear. They are a bit more worn towards the inside than the outside, I didn't notice this last time I rotated the tires though which was about 6 months ago. It isn't a huge difference but it is noticeable if you're looking for it. I haven't been able to check the rear diff fluid due to the weather but will do so asap along with greasing the u-joints and driveshaft (neither of which I'm sure would cause uneven tire wear but still items I need to do) just to keep eliminating the cause of the noise.
I'll be putting her up on stands tomorrow to check for wheel play as well. Thanks everyone for all of the suggestions so far.
Me or the OP? Just trying not to have a heart attack
Well, when I destroyed my rear diff I thought the noise came from the front. Also, every diff I had with a pinion whine had no noticeable play in the bearing. Only thing I can recommend you do is check wheel bearings.
Noises like this are tough to diagnose through a forum, so your issue may very well be different. By 200k it is not a shock to have a worn diff. You should be able to find a low mile used diff. The best part about having a 2WD is that you don't need to worry about matching ratios.
Pull your rear D/S and go for a drive. If it goes away, your rear pinion is done.
That is EXACTLY what it sounds like. The only thing though, is that in this video it seems like the sound comes and goes with the accelerator (or at least that's what it seems like) whereas in my case, even if the car is in Neutral it still makes the same noise while driving at over 30mph.
I put the car up on jack stands today and put it in drive, accelerated a bit, and didn't hear any noise like when I'm driving. What's so befuddling is that there is absolutely no play anywhere and the car drives strong.
Well, when I destroyed my rear diff I thought the noise came from the front. Also, every diff I had with a pinion whine had no noticeable play in the bearing. Only thing I can recommend you do is check wheel bearings.
Noises like this are tough to diagnose through a forum, so your issue may very well be different. By 200k it is not a shock to have a worn diff. You should be able to find a low mile used diff. The best part about having a 2WD is that you don't need to worry about matching ratios.
Thanks for the suggestions. Yea, diagnosing on a forum is tough but just wanted a few ideas on where to look since it didn't seem obvious what and where the noise is coming from. Good to know about the matching ratios too, I didn't know that this didn't apply to the 2WD. Just to be sure though, if you happen to know, the 2WD is 3.73 ratio right?
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