engine quietness in relation to outside air temp.

[RPMster]

car: '06 Hyundai Sonata, 3.3L V6 engine (chain-driven), 85K miles, always properly tuned

Warmer outside air temp (above 70ºF)...

* engine runs quieter, with less vibration

Cooler outside air temp (below 70ºF)...

* engine runs louder, with more vibration, even after a driving for more than 30 minutes
* the cooler the outside air temp gets, the louder it runs (with more vibration, although not what you'd call "rough running")

This has always been the case, the entire time I've owned this car (got it with around 20K miles). When it's warmer than 70º outside, the engine idles so quiet and smooth that you'll forget that it's even running. Under acceleration, it sounds like it's barely working at all. On the other hand, when the outside air temp is cooler, it's the opposite. Not "loud" or "rough" by anyone's definition, just not ultra-smooth like when it's warmer outside.

So, I wanted to present this question for all of you here who pay attention to such details with your own vehicles: - do you notice this same type of pattern?

 

[ls1mike]

The only difference I notice in any of my cars is the WS6 and Buick.
The WS6 is louder when cold but goes away quick. The Buick just runs better with the cold dense. It packs more air in with the blower.

The Truck and the Equinox sound the same regardless of the temp.

 

[shadow7]

I agree that in the winter, my car engine compartment sounds a bit louder. I am not alone!

Also i found that after a long drive(30+minutes), that my car souds a lot quieter in idle.

 

[RPMster]

Thanks for the replies. I'm wondering if this is related to the motor mounts. Mine are the liquid-filled type. Maybe they transmit more NVH through the chassis when it's colder outside? A couple times, when the outside temp got down around 40ºF (which does not happen very often here in Southern California), the engine was very clicky-clacky. Even after a long drive. Still performed well, with lots of power. Just sounded a little diesel-like when it got that cold outside. I'm also wondering if it could just be the cabin insulation letting more engine noise in due to the lower temps, rather than the engine itself. Hmm...

 

[mongo161]

What brand, weight and type of oil are you running?

 

[crazyoildude]

Hyundai is not known for the quietest engines...

 

[SteveSRT8]

yet he just said it was quiet when warm...

May be a timing issue. The PCM can crank in a whole lot more timing if the IAT senses cool air. If your motor moves the cams this may also be a factor.

My car shows no difference in noise but a HUGE difference in power output and throttle response based on temp.

 

[Pop_Rivit]

Of course.

There are all sorts of variations with temperature change. Not only temperature, but humidity and barometric may play a role in what you hear and how the engine may sound. A lot depends on the quality of insulation, motor mounts, etc and how those sounds are transmitted to the cabin.

If you want to have some fun, try driving around in sub zero weather for a while and you'll really hear some odd noises coming from your car.

 

[demarpaint]

My van likes the cold. I had another Ford that liked dampness and humidity. I had a Dodge Van that hated damp and humid climates.

 

[KrisZ]

My car is only louder and "clunkier" during cold start up, after about 15 minutes of driving it idles just the same as during summer. Oh, and my winter temps are usually close to 0 Fahrenheit.

I would check the thermostat.

 

[NateDN10]

I've seen similar things, except that once the engine is thoroughly warmed up, say after 30 minutes of driving, it's just as quiet and smooth as ever.

 

[Whimsey]

Originally Posted By: Pop_Rivit


If you want to have some fun, try driving around in sub zero weather for a while and you'll really hear some odd noises coming from your car.
.

How true

! Especially in a 10 year old pick up truck in the rust belt with leaf springs.

Whimsey

 

[mechanicx]

Originally Posted By: RPMster
Thanks for the replies. I'm wondering if this is related to the motor mounts. Mine are the liquid-filled type. Maybe they transmit more NVH through the chassis when it's colder outside? A couple times, when the outside temp got down around 40ºF (which does not happen very often here in Southern California), the engine was very clicky-clacky. Even after a long drive. Still performed well, with lots of power. Just sounded a little diesel-like when it got that cold outside. I'm also wondering if it could just be the cabin insulation letting more engine noise in due to the lower temps, rather than the engine itself. Hmm...


If the engine is noisier in cool weather even after 30 mins warm up, I'm thinking it is the hydraulic engine mounts. They may be used cheap hydraulic fluid with a low vicosity index or something. The engine is probably always noiser than it could be and the mounts are probably damping the noise at least when the mounts are warm enough and at room temperature.

 

[Mark_Walk]

One way to maybe test this is keep car in garage overnight. The car is warm on start up then drive it early morning when outside air temp is cooler. If it's smooth that would point toward the mounts which were kept warm in garage even though engine is pulling in cold air.

 

[Propflux01]

Originally Posted By: crazyoildude
Hyundai is not known for the quietest engines...

And this comes from where? I have owned several Hyundais, and they are no louder than any other engines, and quite a bit quieter than many I've driven..

 

[Propflux01]

I also agree with Mechanicx. My '06 and my '08 are similar. slightly louder when kept outside in the cold, such as overnight, and barely a whisper when warm.

 

[RPMster]

I'm leaning toward the motor mounts as being the cause. Most normal people (which excludes me) would probably not even notice the little mechanical things that I nit-pick over. Let me put it this way: at it's loudest, my engine is still as quiet as many other modern engines I've experienced. Even when it's around 60º outside, I can still barely hear it running at idle. The engine smoothness really doesn't change substantially until the outside air temp gets down to the low-50's or upper-40's.

One last idea. I've been running Chevron 91 octane since I got the car, because I noticed a slight improvement in throttle response and MPG over 87 octane. The engine does not require Premium fuel, however, and it runs just fine on Regular. Could the higher octane, for some reason, cause the engine to run louder in colder weather (again, even after driving for over 30 minutes with a fully warmed up engine)? I might try a simple experiment to check this as the weather gets cooler soon.

 

[Propflux01]

You will probably notice more tire noise when cold as well, at least I notice it on mine, and that's with several different brands. The higher performance your noticing with premium fuel is the ECM advancing the timing. The car is actually spec'd for 92, but can run 87 because of this.