I've been trying to diagnose this issue I've been having since the purchase of my 1999 4Runner 3.4l 2wd. When I'm cruising under 10 mph and on the gas, everything is cool, but when I left off the gas you wait one second and you can hear this humming sound. It sounds like its coming from the engine only when coasting under 10mph, slightest pressure on the gas and it goes away. You can hear it whenever you are coasting or coming to a stop, until you go over 10mph then it goes away. Any ideas??
Humming noise while coasting??
- Thread starter hec983
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Semper_Fi
New member
just put a new one on mine if that will save you some time
Doc2012
Senior Member
Possible it could be the joints on the DS going out.
When you give it gas, the load from the trans forces the shaft to spin, making the sound only come when it's got no load on it.
See if there's any play in the DS. Get under it and try to wiggle it. If it moves, its probably the joints, which can be replaced.
If not, then check the wheel bearings. Jack the truck up, and holding the tires at 6 & 12, shake them. If there's a lot of play in the tire, the bearings are bad.
When you give it gas, the load from the trans forces the shaft to spin, making the sound only come when it's got no load on it.
See if there's any play in the DS. Get under it and try to wiggle it. If it moves, its probably the joints, which can be replaced.
If not, then check the wheel bearings. Jack the truck up, and holding the tires at 6 & 12, shake them. If there's a lot of play in the tire, the bearings are bad.
Acorn22
Member
Thread resurrection! I've looked everywhere and can't find a definite answer to this...
So I have a 98 limited and since I got it in December, I've had this weird whirring noise that only occurs when I take my foot off of the gas, sound goes away even with the slightest depression of the throttle. Since then, I've replaced both front wheel bearings (were beginning to go bad), changed all diff, t-case, and tranny fluids, put new rotors and pads on + bled the system, and greased both driveshafts but still haven't figured out what the sound is.
U-joints appear to be ok, as do the rear wheel bearings because I'm not getting any noise from them. If anyone can shed some light on this I'd appreciate it!
So I have a 98 limited and since I got it in December, I've had this weird whirring noise that only occurs when I take my foot off of the gas, sound goes away even with the slightest depression of the throttle. Since then, I've replaced both front wheel bearings (were beginning to go bad), changed all diff, t-case, and tranny fluids, put new rotors and pads on + bled the system, and greased both driveshafts but still haven't figured out what the sound is.
U-joints appear to be ok, as do the rear wheel bearings because I'm not getting any noise from them. If anyone can shed some light on this I'd appreciate it!
johnbyebye
New member
Does this noise occur at any speed when you let off the gas?
When I had this issue with my previous vehicle it was the pinion bearing going out.
When I had this issue with my previous vehicle it was the pinion bearing going out.
See this thread for what may be a similar noise that only appears on coasting: http://www.toyota-4runner.org/3rd-gen-t4rs/229758-what-noise.html
I had to get the drive shaft lubed to get the noise to go away
I had to get the drive shaft lubed to get the noise to go away
thegipper
New member
On face value, it sounds like something in the differential. You can disconnect the rear drive shaft and drive in 4wd, if the noise goes away, then its something in your rear differential, most likely pinion or carrier bearings.
When you drained the diff fluid, how did it look?
When you drained the diff fluid, how did it look?
Acorn22
Member
Ok cool thanks for the link and yes it is only when I let off the gas
That's a great idea that I can hopefully do this weekend. When I drained the fluid it was brownish but not all too terrible. There weren't any big pieces of metal on the drain plug either, just some small shavings.
If I can isolate that it's a pinion or carrier bearing, what is my next step?
Thanks everyone
That's a great idea that I can hopefully do this weekend. When I drained the fluid it was brownish but not all too terrible. There weren't any big pieces of metal on the drain plug either, just some small shavings.
If I can isolate that it's a pinion or carrier bearing, what is my next step?
Thanks everyone
johnbyebye
New member
Disregard. Answered my own question. Lol.
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thegipper
New member
If one of those bearings is going bad, the fluid wont necessarily look terrible.
My knowledge in replacing either the pinion or carrier bearing is limited. I do know that it's a somewhat technical repair. I would do some more searching on here or maybe someone else can chime in.
First, lets find out exactly what is causing the noise. Keep us posted.
My knowledge in replacing either the pinion or carrier bearing is limited. I do know that it's a somewhat technical repair. I would do some more searching on here or maybe someone else can chime in.
First, lets find out exactly what is causing the noise. Keep us posted.
2000 Toyota 4Runner v6 2wd
Been having a similar issue but at freeway speed. When letting off gas at 55mph+ it’s like a hum/groan/grind noise sounds like a mix of all 3. Could feel it on the driver floorboard. Also noise is present when VERY lightly pressing gas at freeway you have to hit the sweet spot and the noise stay consistent. I have two videos one is when letting off gas and the other is holding the gas very lightly. So I’ve already changed transmission mount because it was bad. Rebalanced driveshaft because it was missing a weight which helped the trans mount go bad from shaking. New u joints. Supposedly previous owner redid rear diff maybe didn’t do it good idk. So I’m thinking the bad trans mount and driveshaft made something bad in the trans by driving it when driveshaft was out of balance and bad trans mount? I used stethoscope and it does sound louder near output of trans where driveshaft slip yolk goes but it’s hard to tell noise can still travel from rear diff. I think it maybe be trans don’t I don’t want time and money getting one and it’s not I want to make sure first. Here’s link to both videos.
00 4Runner Groan/grind/hum when letting off gas freeway speed - YouTube
00 4Runner Steady groan/grind/hum very lightly pressing gas steadily freeway speed - YouTube
Been having a similar issue but at freeway speed. When letting off gas at 55mph+ it’s like a hum/groan/grind noise sounds like a mix of all 3. Could feel it on the driver floorboard. Also noise is present when VERY lightly pressing gas at freeway you have to hit the sweet spot and the noise stay consistent. I have two videos one is when letting off gas and the other is holding the gas very lightly. So I’ve already changed transmission mount because it was bad. Rebalanced driveshaft because it was missing a weight which helped the trans mount go bad from shaking. New u joints. Supposedly previous owner redid rear diff maybe didn’t do it good idk. So I’m thinking the bad trans mount and driveshaft made something bad in the trans by driving it when driveshaft was out of balance and bad trans mount? I used stethoscope and it does sound louder near output of trans where driveshaft slip yolk goes but it’s hard to tell noise can still travel from rear diff. I think it maybe be trans don’t I don’t want time and money getting one and it’s not I want to make sure first. Here’s link to both videos.
00 4Runner Groan/grind/hum when letting off gas freeway speed - YouTube
00 4Runner Steady groan/grind/hum very lightly pressing gas steadily freeway speed - YouTube
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