Car making noise at idle

Questions on how we spend our money and our time - consumer goods and services, home and vehicle, leisure and recreational activities
Post Reply
User avatar
Topic Author
chickadee
Posts: 231
Joined: Thu Jul 10, 2014 2:13 pm

Car making noise at idle

Post by chickadee » Thu Feb 13, 2020 11:07 pm

So my car is making a rattling vibrating kind of noise that I notice while stopped at stop lights, with foot on the brake. It seems to be coming from under the hood on the passenger side of the car. If you put the car into neutral and take your foot off the brake, the sounds goes away. It’s annoying, pretty loud.

I took it to the independent mechanic I’ve used for years when I was also getting other routine maintenance done. They said they couldn’t replicate it. I’m wondering if they just did the easy work that was in front of them (maintenance) and sent me on my way. He checked the exhaust heat shield, said it was tight.

It’s not intermittent, it’s pretty persistent under the circumstances above. Can’t imagine someone not hearing it.

Should I take it to another independent? A dealer (shudder)?

User avatar
ResearchMed
Posts: 9581
Joined: Fri Dec 26, 2008 11:25 pm

Re: Car making noise at idle

Post by ResearchMed » Thu Feb 13, 2020 11:11 pm

chickadee wrote:
Thu Feb 13, 2020 11:07 pm
So my car is making a rattling vibrating kind of noise that I notice while stopped at stop lights, with foot on the brake. It seems to be coming from under the hood on the passenger side of the car. If you put the car into neutral and take your foot off the brake, the sounds goes away. It’s annoying, pretty loud.

I took it to the independent mechanic I’ve used for years when I was also getting other routine maintenance done. They said they couldn’t replicate it. I’m wondering if they just did the easy work that was in front of them (maintenance) and sent me on my way. He checked the exhaust heat shield, said it was tight.

It’s not intermittent, it’s pretty persistent under the circumstances above. Can’t imagine someone not hearing it.

Should I take it to another independent? A dealer (shudder)?
If it's easily replicable, did you take the mechanic with you when you were driving, so you could say, "There! Do you hear that rattle?"

RM
This signature is a placebo. You are in the control group.

User avatar
Topic Author
chickadee
Posts: 231
Joined: Thu Jul 10, 2014 2:13 pm

Re: Car making noise at idle

Post by chickadee » Thu Feb 13, 2020 11:21 pm

I did not. I dealt with the front desk guy, who relayed what the tech said. That’s been a couple months ago and now I’m formulating what to do next. Perhaps it’s gotten worse, or maybe worse in colder weather? Or it’s just plain getting on my nerves and now I always hear it.

Teague
Posts: 1736
Joined: Wed Nov 04, 2015 6:15 pm

Re: Car making noise at idle

Post by Teague » Thu Feb 13, 2020 11:26 pm

I agree with taking your mechanic for a ride. :happy

I could be all sorts of things. You might get all kinds of opinions trying to diagnose an abnormal sound on an Internet forum. One of them may even be correct, but you won't know which one.
Semper Augustus

User avatar
ResearchMed
Posts: 9581
Joined: Fri Dec 26, 2008 11:25 pm

Re: Car making noise at idle

Post by ResearchMed » Thu Feb 13, 2020 11:29 pm

Teague wrote:
Thu Feb 13, 2020 11:26 pm
I agree with taking your mechanic for a ride. :happy

I could be all sorts of things. You might get all kinds of opinions trying to diagnose an abnormal sound on an Internet forum. One of them may even be correct, but you won't know which one.
Cute! :D

(I sure missed my chance on that one!)

RM
This signature is a placebo. You are in the control group.

bob60014
Posts: 1316
Joined: Mon Jul 31, 2017 8:59 pm
Location: The Land Beyond ORD

Re: Car making noise at idle

Post by bob60014 » Thu Feb 13, 2020 11:40 pm

Make, model and year of vehicle? Depending, it may be a common issue. My son had a similar issue a few years ago and it turned out to be a loose heat shield for the exhaust system.
Last edited by bob60014 on Fri Feb 14, 2020 12:23 am, edited 1 time in total.

User avatar
Cubicle
Posts: 462
Joined: Sun Sep 22, 2019 1:43 am

Re: Car making noise at idle

Post by Cubicle » Fri Feb 14, 2020 12:15 am

chickadee wrote:
Thu Feb 13, 2020 11:07 pm
noise that I notice while stopped at stop lights, with foot on the brake. It seems to be coming from under the hood on the passenger side of the car. If you put the car into neutral and take your foot off the brake, the sounds goes away.
Anything touching the rotors would be where I start looking.

What (if any) work did you have done on the car just prior to the noise starting "a couple months ago"?

barnaclebob
Posts: 4026
Joined: Thu Aug 09, 2012 10:54 am

Re: Car making noise at idle

Post by barnaclebob » Fri Feb 14, 2020 12:20 am

Putting the car in neutral probably changes the rpm of the engine which might get the engine vibrations away from the natural frequency of whatever is vibrating. See if you can get a friend to replicate it for you while you try to locate the noise. Or do that for a mechanic. Dont go to a dealer, theyll want to swap out parts vs just clamping something down.

User avatar
whodidntante
Posts: 7268
Joined: Thu Jan 21, 2016 11:11 pm
Location: outside the echo chamber

Re: Car making noise at idle

Post by whodidntante » Fri Feb 14, 2020 12:57 am

My guess is broken motor mounts. Pretty easy to test for. Open the hood put your face near the engine. Apply full throttle in park. If you are smacked in the face and tattoed with the automaker's logo or decapitated, suspect broken motor mounts. There are probably safer methods, but you get the idea. The engine moves more than a healthy, happy engine with a stable job should.

Failing that, use a mechanic's stethoscope to pinpoint annoying and hard to find noises.

User avatar
Topic Author
chickadee
Posts: 231
Joined: Thu Jul 10, 2014 2:13 pm

Re: Car making noise at idle

Post by chickadee » Fri Feb 14, 2020 1:04 am

No work done prior to noise beginning. Googling did bring up the heat shield issue, which the tech said he checked.

andypanda
Posts: 401
Joined: Sun Nov 12, 2017 9:11 pm
Location: Richmond, Virginia

Re: Car making noise at idle

Post by andypanda » Fri Feb 14, 2020 7:37 am

How many heat shields does your vehicle have? Engine, manifold, exhaust? Are there top and bottom heat shields in various places? One to keep the exhaust away from the gas tank? Sounds can travel in funny ways.

User avatar
mmmodem
Posts: 1924
Joined: Thu May 20, 2010 1:22 pm

Re: Car making noise at idle

Post by mmmodem » Fri Feb 14, 2020 7:48 am

Here's something stupid to check. I had an intermittent rattling that only happened when I was stopped at an red light. Turns out the sound was the hood prop not securely latched. The mechanic would never be able to replicate the sound with the hood open.

User avatar
Topic Author
chickadee
Posts: 231
Joined: Thu Jul 10, 2014 2:13 pm

Re: Car making noise at idle

Post by chickadee » Fri Feb 14, 2020 8:25 am

Unsure on all the heat shields. Will check the hood prop.

tibbitts
Posts: 9501
Joined: Tue Feb 27, 2007 6:50 pm

Re: Car making noise at idle

Post by tibbitts » Fri Feb 14, 2020 9:01 am

whodidntante wrote:
Fri Feb 14, 2020 12:57 am
My guess is broken motor mounts. Pretty easy to test for. Open the hood put your face near the engine. Apply full throttle in park. If you are smacked in the face and tattoed with the automaker's logo or decapitated, suspect broken motor mounts. There are probably safer methods, but you get the idea. The engine moves more than a healthy, happy engine with a stable job should.

Failing that, use a mechanic's stethoscope to pinpoint annoying and hard to find noises.
Broken motor mounts seem like a reasonable possibility, but I've found them hard to identify. And they are more likely to cause a rattle through some seconary effect (allowing something else to touch or vibrate) than directly. Observing the engine when you accellerate in gear (for an automatic at least) seems a better bet, as there should be more torque load on the engine, making it more likely to try to rotate out of its mounts. Obviously you want to be on the side of the car and not in front, and not have your feet in the path of a tire. It's very hard to judge "normal and healthy" unless you've observered and probably recorded a video of how the engine behaves with intact motor mounts, since some movement with typical mounts is normal. Also the vibration-reducing features in the mount can deteriorate without it actually breaking.

lazydavid
Posts: 2761
Joined: Wed Apr 06, 2016 1:37 pm

Re: Car making noise at idle

Post by lazydavid » Fri Feb 14, 2020 9:10 am

whodidntante wrote:
Fri Feb 14, 2020 12:57 am
Failing that, use a mechanic's stethoscope to pinpoint annoying and hard to find noises.
Absent the dedicated tool, a length of heater hose (available at any auto parts store) makes an excellent substitute for a stethoscope in finding these types of noises.

Jack FFR1846
Posts: 11066
Joined: Tue Dec 31, 2013 7:05 am
Location: 26 miles, 385 yards west of Copley Square

Re: Car making noise at idle

Post by Jack FFR1846 » Fri Feb 14, 2020 9:32 am

Motor and transmission mounts are a good first guess. Broken brackets can also potentially do this. For motor mount checking, you sort of need 2 people. One person watching the engine and the other on the brake, in gear and push the gas. If the engine moves in any direction and you hear the noise, there ya go. What kind of car? Transverse mounted engines like in Hondas tend to have a mount on the driver's side, trans mount on the pass side and firewall mount. Longitudinal mounted engines like in a Subaru have more traditional 2 side mounts and a trans mount much farther back. A broken tranny mount is easy to miss because you can't see it easily, sometimes, even on a lift. Depending on the car, it might be mounted to a cross bracket that bolts to the chassis. Missing bolt?
Bogle: Smart Beta is stupid

User avatar
Kenkat
Posts: 5616
Joined: Thu Mar 01, 2007 11:18 am
Location: Cincinnati, OH

Re: Car making noise at idle

Post by Kenkat » Fri Feb 14, 2020 9:42 am

I am on team motor mounts as well. I know Honda had some issues with this, especially around the Odyssey and / or V6 with variable cylinder management (VCM).

bloom2708
Posts: 7214
Joined: Wed Apr 02, 2014 2:08 pm
Location: Fargo, ND

Re: Car making noise at idle

Post by bloom2708 » Fri Feb 14, 2020 9:46 am

Could be the idler pulley or tensioner for the serpentine belt.

When they start to go they rattle and have some play in them.

A mechanic should be able to diagnose that pretty easy. A loose exhaust heat shield is another good idea.
Last edited by bloom2708 on Fri Feb 14, 2020 1:01 pm, edited 1 time in total.
"People want confirmation, not advice" Unknown | "We are here to provoke thoughtfulness, not agree with you" Unknown | Four words: Whole food, plant based

User avatar
Topic Author
chickadee
Posts: 231
Joined: Thu Jul 10, 2014 2:13 pm

Re: Car making noise at idle

Post by chickadee » Fri Feb 14, 2020 11:09 am

Well, just dropped it off at new independent shop near me. Had the “intake” guy come and have a listen. He is also team motor mount at first listen. But we will see once the tech has a root around. Stand by boglenauts!!

It’s a 2010 Hyundai Sonata, which has been a fantastic car. This is really the first thing to go “wrong”, just maintenance up to now. Oh, except the passenger side sun visor.

User avatar
lthenderson
Posts: 4513
Joined: Tue Feb 21, 2012 12:43 pm
Location: Iowa

Re: Car making noise at idle

Post by lthenderson » Fri Feb 14, 2020 11:17 am

chickadee wrote:
Thu Feb 13, 2020 11:07 pm
So my car is making a rattling vibrating kind of noise that I notice while stopped at stop lights, with foot on the brake. It seems to be coming from under the hood on the passenger side of the car.
The easiest way I find to diagnose such problems would be to put my spouse in the drivers seat to replicate the sequence that makes the sound while I wander around trying to get closer to the noise to see what is rattling. Then I can either fix it or tell the repair guy what to fix. Of course if you have a healthy insurance policy on yourself and/or a disgruntled spouse, I wouldn't stand in front of the car while doing so.

User avatar
mmmodem
Posts: 1924
Joined: Thu May 20, 2010 1:22 pm

Re: Car making noise at idle

Post by mmmodem » Fri Feb 14, 2020 12:19 pm

chickadee wrote:
Fri Feb 14, 2020 11:09 am
Well, just dropped it off at new independent shop near me. Had the “intake” guy come and have a listen. He is also team motor mount at first listen. But we will see once the tech has a root around. Stand by boglenauts!!

It’s a 2010 Hyundai Sonata, which has been a fantastic car. This is really the first thing to go “wrong”, just maintenance up to now. Oh, except the passenger side sun visor.
I have a 2009 Hyundai Sonata. The driver side visor fell down. I put a paperclip on it. The trunk prop failed as well and was replaced. Otherwise, no other maintenance issues. Good luck on your investigation. Do come back with the solution. I'm personally interested.

BanquetBeer
Posts: 433
Joined: Thu Jul 13, 2017 5:57 pm

Re: Car making noise at idle

Post by BanquetBeer » Fri Feb 14, 2020 12:26 pm

Keep us updated. I have seen noises from transmission in older econo cars. Shifting in neutral resolves it, dunno if a fluid change would help if it’s a transmission issue.

User avatar
Topic Author
chickadee
Posts: 231
Joined: Thu Jul 10, 2014 2:13 pm

Re: Car making noise at idle

Post by chickadee » Fri Feb 14, 2020 12:29 pm

I will keep the thread updated!

Tranny fluid was changed 3 months ago. If it’s the tranny, need to hop over to the dealer as that should still be in warranty for the next month (10 year, 100,000 mile). I really hate the convenient local dealer. The inconvenient one I haven’t been to.

Yeah, the sun visors seem like an issue. If I remember mine was replaced under warranty. On Hyundai-Forums people report other issues, but so far I haven’t had them. I think it helps that the 2010 was the last model year before a redesign.

The new 2020 Sonata sure looks nice. But I’m attached to my 2010 and it’s been such a good car. Even better than the 1997 Honda Accord it replaced.

User avatar
Topic Author
chickadee
Posts: 231
Joined: Thu Jul 10, 2014 2:13 pm

Re: Car making noise at idle

Post by chickadee » Fri Feb 14, 2020 12:56 pm

And the winner is.......


Drumroll ....



Faulty tensioner for serpentine belt! Which is also causing wear on the belt.

So, fixing both of those, should be ready by 5 pm. He did say that the motor mounts are a little worn, but that it’s not a today problem, so second place goes to team motor mounts.

We will see if “the noise” goes away. (It better).

Thanks all!

User avatar
Topic Author
chickadee
Posts: 231
Joined: Thu Jul 10, 2014 2:13 pm

Re: Car making noise at idle

Post by chickadee » Fri Feb 14, 2020 6:01 pm

Listened to the sounds of silence on the way home. Yay!

h82goslw
Posts: 136
Joined: Fri Jun 17, 2016 5:44 am

Re: Car making noise at idle

Post by h82goslw » Fri Feb 14, 2020 6:35 pm

whodidntante wrote:
Fri Feb 14, 2020 12:57 am
My guess is broken motor mounts. Pretty easy to test for. Open the hood put your face near the engine. Apply full throttle in park. If you are smacked in the face and tattoed with the automaker's logo or decapitated, suspect broken motor mounts. There are probably safer methods, but you get the idea. The engine moves more than a healthy, happy engine with a stable job should.

Failing that, use a mechanic's stethoscope to pinpoint annoying and hard to find noises.
:D :D :D

Post Reply