Does anyone know what this noise could be?

[Gigi]

I would put the car on a car lift to have access under the car. Take all under car covers off and start the car. Inspect the area the noise is coming from. You can not find where the noise is coming from the ground. Period. Good luck. p.s. aos does not makes any noise, but white smoke.

[blue62]

Sounds like a fan belt tensioner bearing going out.
But it is a video so it is a wild ass guess at best.

you could remove the engine cover behind the seats and have a listen.
Use a piece of hose (like garden hose or heater hose) like a stethoscope.
That way you can pin the noise down better then just listening in the normal way.

You could remove the fanbelt and run the engine for just a few minutes to see if the noise stops.
if it does then the fan belt tensioner or the altenator or the water pump is the issue.

Keep us posted.

how many miles on it??

[78F350]

Originally Posted by blue62

... you could remove the engine cover behind the seats and have a listen.
Use a piece of hose (like garden hose or heater hose) like a stethoscope.
That way you can pin the noise down better then just listening in the normal way.

You could remove the fanbelt and run the engine for just a few minutes to see if the noise stops.
if it does then the fan belt tensioner or the altenator or the water pump is the issue.
...

I can't get the video to play, but I agree This is the best advice so far.

No harm in replacing the AOS preemptively whether it was the problem or not

Since the video didn't work for me, extra questions:

• Is it only driving the car or just engine running?
• Noises up front could easily be a bearing on an idler pulley or belt driven accessory.
• Two fans on the right side - engine compartment cooling and SAI Blower.
• Loose spark plugs chirp.
• Wheel bearings or brake related noises when the car is moving? I had an E-Brake pad drag that made a whine.
• I'd expect that vacuum leak large enough to make much noise should be large enough to trigger a check engine light.
• Exhaust leak at the header/O2 sensor?

[blue62]

Originally Posted by 78F350

I can't get the video to play, but I agree This is the best advice so far.

No harm in replacing the AOS preemptively whether it was the problem or not

Since the video didn't work for me, extra questions:

• Is it only driving the car or just engine running?
• Noises up front could easily be a bearing on an idler pulley or belt driven accessory.
• Two fans on the right side - engine compartment cooling and SAI Blower.
• Loose spark plugs chirp.
• Wheel bearings or brake related noises when the car is moving? I had an E-Brake pad drag that made a whine.
• I'd expect that vacuum leak large enough to make much noise should be large enough to trigger a check engine light.
• Exhaust leak at the header/O2 sensor?

The video is with the car stationary so that narrows down the issue considerably.

If it was a vacuum leak big enough to hear when standing next to the car it would not only trigger a check engine light as you mention but the car would shake like hell at idle, Although I doubt it would idle with a vacuum leak that big.

I think the SAI blower only kicks in on cold start and for very short time. So I don't think it is that.

If he had an exhaust leak big enough to be heard it should trigger a lean code and or a Cat efficeincy code.

So diagnostics are narrowed down greatly.
the most likely issue is one of the three things I mentioned.
or the engine bay cooling fan as you mention.

In the video it sounds like a "rotational mass squeak" to me.
But it is a 12 second video at idle only so there's that.

If he would have run the video longer and varied engine speed just a little I could have listened for if and how the sound changed.
That can be telling at times.

If he removes the fan belt and runs the engine for a few minutes he can either eliminate three possible suspects (if the sound is still there) or narrow the issue to one of three suspects (if the sound is gone).

So it would be a good diagnostic gain for the time spent.

Woops
four suspects I forgot about the air-conditioner pump.

[Infernous428]

Here is a longer video with more revs etc.. had a smoke test done and there's no leaks found. No engine codes either. Sound seems to be coming around the cats etc. Not sure where what it could be. Mechanic said he doesn't just want to start waiting for random parts replacement and to come back when a code comes up so he knows where to begin:

https://www.veed.io/view/abeb01ba-874d-4109-a15f-58720e9a1c9a

Originally Posted by blue62

The video is with the car stationary so that narrows down the issue considerably.

If it was a vacuum leak big enough to hear when standing next to the car it would not only trigger a check engine light as you mention but the car would shake like hell at idle, Although I doubt it would idle with a vacuum leak that big.

I think the SAI blower only kicks in on cold start and for very short time. So I don't think it is that.

If he had an exhaust leak big enough to be heard it should trigger a lean code and or a Cat efficeincy code.

So diagnostics are narrowed down greatly.
the most likely issue is one of the three things I mentioned.
or the engine bay cooling fan as you mention.

In the video it sounds like a "rotational mass squeak" to me.
But it is a 12 second video at idle only so there's that.

If he would have run the video longer and varied engine speed just a little I could have listened for if and how the sound changed.
That can be telling at times.

If he removes the fan belt and runs the engine for a few minutes he can either eliminate three possible suspects (if the sound is still there) or narrow the issue to one of three suspects (if the sound is gone).

So it would be a good diagnostic gain for the time spent.

Woops
four suspects I forgot about the air-conditioner pump.

[blue62]

Originally Posted by Infernous428

Here is a longer video with more revs etc.. had a smoke test done and there's no leaks found. No engine codes either. Sound seems to be coming around the cats etc. Not sure where what it could be. Mechanic said he doesn't just want to start waiting for random parts replacement and to come back when a code comes up so he knows where to begin:

https://www.veed.io/view/abeb01ba-874d-4109-a15f-58720e9a1c9a

If "you" want to diagnose the cause then you need to start eliminating possibilities.
The easiest way to start doing that is to remove the fan belt (serpentine belt).
If the noise persists after removing the fan belt and running the engine then you will know it is not anything driven by the belt.

If the noise is gone after removing the belt then it is something driven by the belt.

Your not going to get far by just posting video's and asking random people or random mechanics their opinions.
Diagnostics has to be done, that basically boils down to a process of elimination.

I notice a lot of liquid dripping from under the car.
Whats going on there.???

What modifications have you done to the car?
Doesn't look like stock exhaust or it isn't bolted up correctly.

[Homeoboxter]

To me it sounds quite like this:
https://www.youtube.com/watch?v=YK2ihM9-JaQ&t=4s

But seriously, you don`t even need to pull the belt, you can just loosen it up by releasing the tensioner roller for a couple seconds while idling using a breaker bar. Everything that the belt drives will stop and that will narrow down the potential causes, as Blue suggested.

[Infernous428]

It used the have an aftermarket exhaust, and I recently had the stock exhaust reinstalled and that's how they did.

The dripping is because it had been pouring outside and I had just driven the car in heavy rain.

I will start with the belt and see what I can find. Honestly the noise doesn't start until about 10 min of driving. How long can I run the car on jdle the car without the belt?

Originally Posted by blue62

If "you" want to diagnose the cause then you need to start eliminating possibilities.
The easiest way to start doing that is to remove the fan belt (serpentine belt).
If the noise persists after removing the fan belt and running the engine then you will know it is not anything driven by the belt.

If the noise is gone after removing the belt then it is something driven by the belt.

Your not going to get far by just posting video's and asking random people or random mechanics their opinions.
Diagnostics has to be done, that basically boils down to a process of elimination.

I notice a lot of liquid dripping from under the car.
Whats going on there.???

What modifications have you done to the car?
Doesn't look like stock exhaust or it isn't bolted up correctly.