Help diagnose screeching noise

[Carbonn]

I'm hoping to get some help and guidance on diagnosing two noises. I've searched/read on the forums and wiki sections and couldn't find similar symptoms.

Firstly, I hear a high pitch screeching noise coming from the right side of the NSX. It's difficult to exactly tell if the noise is from the front or rear of the car (sounds more towards the rear). Let me try to describe the scenario in how the noise comes about.

I do a cold start-up, the NSX runs smoothly on idle and revs smoothly with no screeches or squeaks (I've opened the engine hatch and hear nothing unusual). After a few minutes of warm up, I gently reverse out a little and then put into first gear to pull out of my drive way on to the road (drive 30 feet) with very minimal throttle (about 1K RPM) and there is no noticeable screeching noise. I stop at an intersection and when the traffic clears, I engage first gear and add throttle to drive across the intersection. At about 2K RPM, the loud high pitch screeching begins and continues screeching to about 4K RPM. The screeching noise suddenly disappears while I'm still adding throttle, and I then let off the throttle and step on the brakes gently to come to a complete stop. After stopping, I proceed to drive normally on first gear again and the screeching noise is gone. I'm unable to replicate the noise after the car warms up driving on the road. Sometimes the screeching noise comes back intermittently while driving, but it's very faint and brief (not consistent).

From what I've observed, the screeching noise is easier to replicate after the NSX has been sitting for about 12-15 hours. I've tried to replicate the screeching noise after the NSX sits for 8 hours and it doesn't screech as much (quite strange). Here's a recorded sound clip of the screeching noise (click on the link below) along with the description outlined below. What do you think could be causing the screeching noise?

Sound clip: https://voca.ro/kt8lyU3hJoL

00:01-00:06 second mark - I'm waiting at an intersection with my left turn signals on.
00:07 second - I let out the clutch in first gear to turn left.
00:09 second - As I'm turning, the screeching noise begins (noise coming from the right side of the car).
00:10-00:15 second - A high pitch screeching noise continues from 2K-3.5K RPM in 1st gear while strolling through 50 feet of road.
00:16-00:17 second - The screeching noise mysteriously disappears around 4K RPM.
00:18 second - I let off the throttle and coast in 1st gear.
00:20-00:21 second - A light screech noise reoccurs again a short bit while coasting.
00:29 second - I gently press on the brakes to stop and there is a faint metal squeal whistling noise coming from the right side.

The second noise I'm trying to identify is a brief "guh guh gok" rubbing scuff noise when slowly turning right up on to a drive way from coasting momentum in neutral. The noise happens in a quick second and it sounds like it's coming from right rear side. I wasn't able to record the sound since it's hard to capture, but it's audible to the ear in-person. What could be causing the second noise?

 

[drew]

Really sounds like brake splash shields rubbing on rotor or low pad thickness. Things either heat up or slightly wear away.

You're going to have to take off the tire and inspect the splash shields and pad thickness.

If the pads are close to the service limit, you might as well change them out...make sure to clean and use caliper grease on the guide pins.

 

[dquarasr2]

Really sounds like brake splash shields rubbing on rotor or low pad thickness. Things either heat up or slightly wear away.

You're going to have to take off the tire and inspect the splash shields and pad thickness.

If the pads are close to the service limit, you might as well change them out...make sure to clean and use caliper grease on the guide pins.

Brakes are exactly what I thought when I listened to the audio.

 

[Old Guy]

Indeed, brakes would be a good thing to check. If the noise is originating at the pad / disk interface area, a possible test is when the noise is present, maintain speed and apply the brakes (not too hard). If you hear an immediate change in the noise you may have a problem with the pads (failing to retract / jamming sideways in the caliper / who knows what). Wheel removal is required for further diagnosis. If the noise does not change with application of the brakes, the noise may originate elsewhere.

At about 2K RPM, the loud high pitch screeching begins and continues screeching to about 4K RPM. The screeching noise suddenly disappears while I'm still adding throttle, and I then let off the throttle and step on the brakes gently to come to a complete stop.

If the noise occurs in every gear between 2000 - 4000 RPM, then I would look at the engine - alternator, air conditioner clutch (was the AC on and cycling when you did your test) TB tensioner or water pump.

 

[Carbonn]

Thank you drew, dquarasr2, and Old Guy for helping to diagnose and providing your feedback. At first I also thought it sounded like it might be coming from the brakes because of the metal to metal contact noise, but it puzzled me when the noise would go away by itself after the initial drive. Stepping on the brakes also doesn't make the same level of noise. On some days the screeching noise would be louder than other days.

When I recorded sound clip of the noise, the air conditioning was turned off and windows were rolled down, so I could best capture the noise. So far, I've only heard the screeching noise on first gear with the windows rolled down. I haven't heard the noise when shifting/driving in other gears. It just so happened I was able to record the screech when it occurred on first gear between 2-4K RPM. Sometimes the noise occurs around 1.5K RPM and goes away around 3K RPM, and the volume/pitch of the screech can vary.

Old Guy - thanks for the suggestion on a possible test: "when the noise is present, maintain speed and apply the brakes (not too hard)". If I understand correctly, when the screech noise is present, to hold the throttle (keep constant, but not increase/decrease), and lightly press the brake little to hear a change in the noise. I'll try this out first. I'll also have the NSX's brakes checked with the wheels taken off and opening the calipers by a mechanic.

 

[Old Guy]

Old Guy - thanks for the suggestion on a possible test: "when the noise is present, maintain speed and apply the brakes (not too hard)". If I understand correctly, when the screech noise is present, to hold the throttle (keep constant, but not increase/decrease), and lightly press the brake little to hear a change in the noise. I'll try this out first. I'll also have the NSX's brakes checked with the wheels taken off and opening the calipers by a mechanic.

Yes, that is correct. If the noise changes when you lightly apply pressure to the pedal then chances are the problem is with the brakes. No change in noise, chances are the problem is somewhere else.