Noise at Certain RPMs 3rd Gen v6

C

concerto5

New member
My Car:

2000 4runner v6 auto transmission, no lift, regular sized tires.

Problem:

As soon as I get to 2.5k RPMs and above, in any gear, there is a sound that seems to be coming from the front half of the car (can't pinpoint it). It is a low, deep hum/vibration. It is very similar to when you run over the warning paint on the highway (you know the ones that make noise to wake you up, though not as loud. It is a low whisper of a hum). It does it when it is cold and hot. I cannot get it to change pitch/volume by turning sharply or going uphill/downhill. It is the same consistent sound always--and it always starts at 2.5k rpm....exactly everytime. If I punch the gas and get it to 4k rpms or above, the noise seems to taper off.

Additional info:********
1. UPDATE: When in park or neutral (not moving) and when reving the engine up , it does make the sound.
2. No noise comes from tires when driving really--so I assume its not that.
3. As soon as I let off the gas pedal (when I am in the high RPMs and the noise is going) it immediately stops.


In general there are no problems other than this on the car...no other noise, no shifting problems.

Any ideas are appreciated.
 
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Is it a sort of rattle-sound? I know toyota engines can get that when you are giving it throttle or going up hill. My family has had many toyota's (cars and trucks) and some (but not all) sometimes get this pingy/rattle when you give it alot of gas. Is it just a sound or can you feel it at all (vibration etc)? Does the engine feel like it is struggling at all or bogging down or does the actual performance of the engine feel the same?

You might want to try some fuel injector cleaner and running through some higher octane gas? Just a thought. I really am no expert though.
 
It is more of a loud humming sound than vibration...though you can feel the vibration. It echoes throughout the front part....feels like it is right beneath me.

The driveshafts were just greased last week....however I bought this car used and not sure when they did it last.

When the vibration/humming starts...there is not loss of power at all. The acceleration/drive/power of the engine does not change at all.

I'm lost with ideas because there are no 'side symptoms' with it. I know it's something ...
 
Double check your support bearing and double cardan for free play smooth operation and any gritty grinding noise.

To do so, on level ground shift into neutral and shut the truck off, apply the parking brake. You will be jacking up the rear axle so one tire is off the ground but first chock the opposite front tire from the you will be lifting. With the wheel chocked release the parking brake and then crawl under the truck and turn the shaft by hand. It should rotate with minal effort. Also try to push and pull the shaft near the bearings to see if there is any noticeable lateral movement. Listen closely for any gritty or clunking noise.

I'm really thinking one of them is out as they are the only things "right under you in the middle" that do not rotate when in park but do as you drive.

It's possible you ruptured the bearings when you greased them last week by over greasing.
 
Your truck is a 2000 is it a 4WD and does it have the chain drive or center diff "push button awd" transfer case?
 
Ive only had problems like that in Fords I have owned but it sounds like a torque converter to me. If not that then probably 4wd components. I have haf luck with the lucas transmission goo. Stopped it in a Tbird I owned as a kid. Never had another issue with it.
 
Well it wont say AWD it says 4WD I belive. Can you post a picture of your gear shift?

Also why you're in your truck try keeping your foot firmly on the brake with your left foot, and shifting into each gear starting with 1 or low and giving it a bit of gas to see how hard the truck pulls or bogs and see if your sound comes in. It wont take too much throttle, do NOT floor it, just about 1/4 throttle should be fine. If your sound comes in it may be your torque converter as was previously mentioned. In which case I can't help you too much, I'm manual and don't have much knowledge on automatic trans issues.

Something else you can do though is check your level colour and consistency of your ATF. Also while your at it, check your coolant to make sure you haven't milkshaked. When's the last time you changed the radiator?
 
Great ideas...lots of stuff to try.

I bought it used so I am not completely sure about the radiator. One thing I found interesting is a little rusty color/copper looking residue on the bottom of the rad cap. I'm thinking either rust/corrosion or stop leak. This truck was sitting for a couple years.

About the milkshake...I just installed a B&M tranny cooler and bypassed the rad entirely a couple days ago. When I checked coolant/tranny fluid it looked good. I will look again more closely.

I will check the driveshaft support bearing/torque converter sometime this week.
 
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Btw...I have:

(standard "J" t-case shifter)
1st position: 2HI
2nd position: 4HI (locked only)
N
3rd position: 4LO


No button on side of shifter for AWD.
 
Ok update on this noise.

It DOES have the sound when in Park and not moving. Based on this I am guessing this rules out driveshaft/transmission?

I tried the test with keeping foot on brake and pressing throttle at same time--no new sound or anything from that. Also guessing it is not the torque converter.

Also I am currently getting junk MPG (replaced plugs/wires/o2 sensor/seafoamed/air filter/throttle body MAF sensor). 14 mpg mixed--mostly hwy.

Any thoughts?
 
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There are a bunch of other threads on this issue that all start around 2500 rpm but I haven't seen a definitive solution yet unfortunately. My 2000 Ltd does the same thing for whatever it's worth. It almost seems to be transmission related at times but doesn't seem to affect anything in terms of drivability.
 
Suggestion: pull your skid plates off and see if that affects it.

I used to get a vibration (more of a buzz) right around that RPM range. It turned out to be the second, smaller skid plate, and I fixed it by putting a few pieces of sound deadener on the top side of the plate.

Near as I can tell, it's caused by that plate resonating with the engine and vibrating against something. Damp the resonance, and the buzz completely went away.
 
Here is some additional information. Not sure if it is related and am putting here anyways because it seems like it might be.


1. I bought the car about 2 months ago. About 500 miles in, sometimes when starting it cold I shift into reverse and it will not go. If I press the gas--it will engage within a 2-3 seconds. Never a problem getting into drive. And no problems shifting or slipping afterwards. Reverse works after it first engages.
2. When completely stopped and when it is in drive, it doesn't move like a normal auto tranny does. To be clear....it seems to accelerate fine--no slipping and there is a lot of power. However, you know in a regular auto car when you let off the brake, when in drive, at a dead stop it will move on its own? Mine is so weak...and if it is on the slightest incline it will actually roll back in drive.
3. ************ I checked the tranny fluid about 2 weeks ago...and it was red color and the proper level. HOWEVER, a few days ago I checked it and it was brown and smelled burnt. I immediately did a COMPLETE fluid replace (taking a/c cooler outtake and draining 15 qts---replacing a qt at a time). After the flush (drove about 125 miles on it so far...fluid still red so far) I haven't had the reverse problem again.

I'm thinking it is a Torque Converter..but it may not be. If you can tell what my problem may be by the symptoms above, fantastic ...let me know. Otherwise, what would be things to look for if it was a bad TC?

Thanks.
 
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