Rumbling/vibration with light throttle

[miltoney]

Just picked up an 18 Legacy 2.5i a couple days ago. It has an issue where upon very light throttle depression, there is a rumble, almost like the sound a car with a traditional transmission would make when it is in too high of a gear for the speed and needs to downshift. There is also a minor vibration with it. It only occurs with light throttle input, like enough to maintain speed on a flat road. Foot off the gas, it stops. Foot into the gas, it stops. It is most prominent at lower speeds, I don't notice it on the highway at 70 plus.

 

Needless to say, this makes driving anywhere but the highway less than desirable. I did notice a rumble during my test drive but thought it was the bass from the Harmon Kardon, because it seemed to stop when I turned the radio down.

 

Anyone have any idea what this could be? Very frustrating considering I just bought the car. It is obviously going to the dealer, but I don't have alot of faith in them and would like to arm myself with as much knowledge as possible.

[MoleMan]

Sounds like a CVT to me. Mine makes somewhat of a “rumble” noise at very low speeds or if the car is parked and I feather the throttle. However no issues with operation and Imwould describe the noise level as a 1 on a scale of ten so basically more wind noise then that noise is noticeable. Anyhow I would take it to the dealer and maybe change the fluid and see that everything is ok if you are worried at all.

 

Maybe it’s the cars way of saying “welcome to the wonderful world of CVts”

 

You want a bad CVT go drive a 2006 or so Nissan Murano that thing whines more then a Dustbuster about to explode.

 

It could also as you stated be a product of a loose component possibly in the stereo such as a blown speaker. But the person who owned it before you could have had that thing on full every time the car started. But it would produce more of a rattle not a rumble in my opinion.

[miltoney]

Not saying that it's not the cvt, but it is definitely not a 'normal' cvt sound. It is actually quite uncomfortable to listen to for any length of time, and it is a relief to get on the highway where the noise stops (and then the excessive road noise kicks in, but thats neither here nor there).

 

I owned a 17 legacy for a couple years that didn't make this sound.

 

Thanks for your input, I appreciate it

[MoleMan]

Not saying that it's not the cvt, but it is definitely not a 'normal' cvt sound. It is actually quite uncomfortable to listen to for any length of time, and it is a relief to get on the highway where the noise stops (and then the excessive road noise kicks in, but thats neither here nor there).

 

I owned a 17 legacy for a couple years that didn't make this sound.

 

Thanks for your input, I appreciate it

 

Your 17 also had the CVT so if it was that you would probably be very familiar with the noise.

 

My guess is it’s probably a loose trim piece or just a guess here could be a heat shield. But heat shields generally don’t rumble but buzz and get annoying as hell. And they will do what you describe sometimes at lower speeds and then do nothing on the highway. Maybe try getting up under the car and see if anything is loose at all.

[DougKelly20]

Exhaust leak?

[MoleMan]

Exhaust leak?

 

 

Very good place to check while under the car. That would explain the “rumbling” sound at lower speeds. But OP says nothing is happening on the highway. But maybe it’s because the radio is on and the engine is at a constant speed.

[Beamercub]

Question: Why did you get the 18'? Did something happen to the 17' ?

 

As for suggestions on the sound, I would lean more towards the engine, or possible a motor mount?

 

You have owned basically the same car, it would be an insult to suggest it could be something you would clearly be able to diagnose yourself..

[miltoney]

Kind of a long story, I traded in the 17 for a truck and then about 6 months ago we tried to sell my older 2012 legacy but I couldn't get what I wanted for it, so my wife and I talked and decided to get rid of the truck and bank some money for as long as I could keep the car running. Well, as soon as I sold the truck, that car was nothing but problems, I was working on it every weekend. I got sick of it and traded that car in for this 18.

 

It's a beautiful car, a limited with only 24000 miles, was apparently kept in a garage because even the underside of it still looks brand new. But I think I see why someone traded it in!

 

As far as diagnosing, I am pretty mechanically inclined, I do most of my own work. I even changed the timing belt on my 12'. But I have never heard anything like this sound. Whatever it is, it is definitely not right, and I suspect it could be something serious. I did purchase a good warranty, so it will get fixed, eventually.

[DougKelly20]

Very good place to check while under the car. That would explain the “rumbling” sound at lower speeds. But OP says nothing is happening on the highway. But maybe it’s because the radio is on and the engine is at a constant speed.

Yeah my thought was lack of LOAD on the highway which can typically quiet the exhaust sounds that relate to "rumbling"...kinda like an aftermarket exhaust will drone up a hill but not down.

[tchads57]

New member here and hoping for some guidance on a 2015 Legacy, 58,600 miles.

I have a low pitch whirring noise coming from the back of the vehicle. It seemed to come from the right rear and was most noticeable at 35-55 mph. The frequency changes with speed, but the general pitch remains the same. I put the rear seats down and the sound shifts to the center. I switched the tires to the snow tires early to see if it was tire related, no change.

I thought wheel bearing and the dealer confirmed the noise and replaced the 2 rear bearings yesterday. Driving home I thought I could still hear the noise. I won’t be able to check until the rain stops, too much background noise on the highway. If it is still there, what are other possible causes of this type of noise? Aside from the Starlink system the car has been great.

Thank you.

 

PS: If this is covered in another thread please let me know

Edited October 30, 2021 by tchads57
Added PS

[MoleMan]

New member here and hoping for some guidance on a 2015 Legacy, 58,600 miles.

I have a low pitch whirring noise coming from the back of the vehicle. It seemed to come from the right rear and was most noticeable at 35-55 mph. The frequency changes with speed, but the general pitch remains the same. I put the rear seats down and the sound shifts to the center. I switched the tires to the snow tires early to see if it was tire related, no change.

I thought wheel bearing and the dealer confirmed the noise and replaced the 2 rear bearings yesterday. Driving home I thought I could still hear the noise. I won’t be able to check until the rain stops, too much background noise on the highway. If it is still there, what are other possible causes of this type of noise? Aside from the Starlink system the car has been great.

Thank you.

 

PS: If this is covered in another thread please let me know

 

The dealer replaced the bearings so you should not be hearing the noise. you said you switched to your snows which would be louder then the all seasons. So its probably just the snow tires making a louder noise which thats what they do. If its any help both my 4th gens both had wheel bearing failures in the 40K range.

[miltoney]

Exhaust leak?

 

I don't think its an exhaust leak, although I haven't 100% ruled it out, but it just doesn't sound like that. it sounds more internal, and the underside of the car certainly doesn't have enough corrosion (has almost none) to make me suspect that, unless there is a defect in the exhaust somewhere.

 

I'm just afraid the dealer is going to tell me they don't hear it, or that it's normal. I swear I will lose my shit if they tell me that...

[MoleMan]

Only saving grace is no codes are popping up on your dash so we know its not engine or Cat related.

 

It could be a damaged muffler lol.. My guess it a leak somewhere. It does not need to have corrosion to have an issue. It could just be something loose.

[tchads57]

Thanks MoleMan. I had the snows put on to rule out tire noise. There is still a noise, but not as loud. I was wondering if wheel bearings wear out quicker on an all wheel drive car.

I drive 10 miles to work each day and 9 of it is on highway, so I can check the noise level at different speeds.

Right now, I’ll call the dealer and mention that the noise better but still there. If it’s possible the front bearings are gone too, I may try the replacement myself. Maybe…..

[Grnlantern1]

Thanks MoleMan. I had the snows put on to rule out tire noise. There is still a noise, but not as loud. I was wondering if wheel bearings wear out quicker on an all wheel drive car.

I drive 10 miles to work each day and 9 of it is on highway, so I can check the noise level at different speeds.

Right now, I’ll call the dealer and mention that the noise better but still there. If it’s possible the front bearings are gone too, I may try the replacement myself. Maybe…..

You need a press to remove the front I believe.. The rear they replace the entire hub.. Hopefully it's just a Bearing issue..

 

Another person on the forum stated he had a transmission noise or issue and ended up blowing out the Transmission literally put a hole in the transmission and dealer told them something in the transmission failed.. Sorry I can't remember exactly the part and which topic..[emoji17]

 

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[Painless]

miltoney

I had what may be similar symptoms (as far as noise is concerned) in my '16 2.5i.

Rumbling that increased with engine rpm but seemed to be less loud after the car was warmed-up/driven a bit. We did have an exhaust smell as well though.

Turned out to be a crack had formed in the bellows of the front exhaust.

It is unfortunately tough to verify for sure as there is shielding and insulation over the entire assembly.

Link to my posts for reference:

https://legacygt.com/forums/showthread.php/exhaust-smell-recall-wuj-95-281725p5.html

See post#73 for my findings.

This is a known issue and there is a recall WUJ-95 though they refused to cover mine and I had to replace it myself.

Hope this helps.

[miltoney]

miltoney

I had what may be similar symptoms (as far as noise is concerned) in my '16 2.5i.

Rumbling that increased with engine rpm but seemed to be less loud after the car was warmed-up/driven a bit. We did have an exhaust smell as well though.

Turned out to be a crack had formed in the bellows of the front exhaust.

It is unfortunately tough to verify for sure as there is shielding and insulation over the entire assembly.

Link to my posts for reference:

https://legacygt.com/forums/showthread.php/exhaust-smell-recall-wuj-95-281725p5.html

See post#73 for my findings.

This is a known issue and there is a recall WUJ-95 though they refused to cover mine and I had to replace it myself.

Hope this helps.

 

Interesting, thank you. Although being an 18, this shouldn't be my problem.

 

The dealer looked at it today and I got exactly the response I expected. They told me over the phone they couldn't hear anything, so when I got there i asked one of the "techs" to ride with me. Of course with me in the car there was no denying the sound, and he said it sounds like tires to him...lol. so I said to him funny the tire sound stops everytime I take my foot off the gas. Then he changed his tune and started going on about the cvt and how it runs in a high gear to save fuel bla bla bla...the guy was obviously clueless.

 

I don't know, I guess I'll just ride it out for a while, see what happens. It's not that bad, I can tolerate it, I just don't think its right.

[tchads57]

Thanks grnlantern. I was hoping the front bearings would be similar to the rear. We drive to VT regularly a (bought the Subaru to fit in) and don’t need a major failure while on the way there.

Transmission, I hope not. I assume the noise will get louder as the part fails and then…..who knows.

[ammcinnis]

I was hoping the front bearings would be similar to the rear.

Contrary to the post by grnlantern, the front wheel bearings of all Gen 6 Legacys are cartridge-style hub/bearing assemblies, similar to the rear bearings (but not identical). See attachment, from the FSM. Front or rear, it is not unusual for the hub/bearing assemblies to rust firmly into the suspension knuckles, making removal a challenge. (This is not just a Subaru issue; it affects all manufacturers.)

[MoleMan]

Miltoney,

 

The tech could be absolutely right as far as the tire theory. Can you please indicate what brand and size tires you have please and what the tread level is as well as that could play a big role if it is in fact tires. 4/32 of tread is a lot more noisy then 10 or 8/32 and I generally replace all of mine at 4/32 because of the loud grumbling and general loudness at this point.I personally have become Uber sensitive to tire noise in my cars in the last ten years or so. Since you are hearing a rumbling sound it could very well be the tires. However I generally hear that noise in the tires at highway speeds or on rougher pavement never at super low speeds at all.

 

As far as the wheel bearing issue on both my 4th gens I thought it was the tires however My mechanic had to listen to the bearings as my issue was more of a binding feel at speed with very minimal noise. This does not seem to be the case in your situation however.

[miltoney]

Miltoney,

 

The tech could be absolutely right as far as the tire theory. Can you please indicate what brand and size tires you have please and what the tread level is as well as that could play a big role if it is in fact tires. 4/32 of tread is a lot more noisy then 10 or 8/32 and I generally replace all of mine at 4/32 because of the loud grumbling and general loudness at this point.I personally have become Uber sensitive to tire noise in my cars in the last ten years or so. Since you are hearing a rumbling sound it could very well be the tires. However I generally hear that noise in the tires at highway speeds or on rougher pavement never at super low speeds at all.

 

As far as the wheel bearing issue on both my 4th gens I thought it was the tires however My mechanic had to listen to the bearings as my issue was more of a binding feel at speed with very minimal noise. This does not seem to be the case in your situation however.

 

The tires are brand new. Dealer installed when I bought the car. It's not the tires or sound would persist regardless of throttle position.

[tchads57]

I doubt it would be the bellows in my case. I’ll put the car into neutral on the highway, coast down a hill and can still change the frequency using the brakes. I’m almost positive it’s drivetrain or bearing related.

I’ll have my tire person rebalance the rear wheels as it looks like some weights were knocked off.

[Grnlantern1]

Contrary to the post by grnlantern, the front wheel bearings of all Gen 6 Legacys are cartridge-style hub/bearing assemblies, similar to the rear bearings (but not identical). See attachment, from the FSM. Front or rear, it is not unusual for the hub/bearing assemblies to rust firmly into the suspension knuckles, making removal a challenge. (This is not just a Subaru issue; it affects all manufacturers.)

Thank You for the info.. I'm not an Expert Mechanic. Just remember how much a pain my 98 2.5rs was.

 

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[MoleMan]

The tires are brand new. Dealer installed when I bought the car. It's not the tires or sound would persist regardless of throttle position.

 

 

You would be surprised if I put a set of Nanking tires on and told you to drive 500 miles and then put a set of Michelin or Continentals on and told you to drive another 500 miles. Dealers are going to put the cheapest tires on they can especially independent ones.

 

I have had brand new sets of tires be loud as hell. All I can say at this point is take it to a shop and have them put a scope on the wheel bearings and see if that’s the issue. Make an emphasis on the wheel bearings.

 

Since you came from a 16 we know it’s not the CVT making noise at all. Car is not throwing any codes so we know it’s now engine related. The sound is not a heat shield. Only three options left really. A bad wheel bearing or bearings, bad tires, or something in the exhaust.

 

However just gonna throw this out. If the CVT fluid change was done wrong and is underfilled or overfilled could it make this type of noise?

[miltoney]

Well today I finally had a chance to look the car over really good myself, and I'm a little embarrassed to say that I think the sound is coming from the exhaust. I had my wife give it a little gas while I stood outside the car (she heard the sound immediately by the way, so I'm not crazy!), and I could clearly hear the rumbling coming from the muffler. I don't know if it's supposed to sound like this, I find it hard to believe Subaru would put something like this on a Legacy. The muffler still looks almost brand new, but I realize there could still be a pinhole in it somewhere.

 

It is definitely not tires, they are in fact shitty tires the dealer installed, and they are noisy as hell on the highway, but this is not the sound I am talking about.