Rattling noise under the hood during engine braking at low RPM

[LSV8]

I noticed this same sound and it is the clutch. All normal.

[prest1ge]

noticed the sound since day one. sounds REALLY ugly IMO and makes me feel a little embarrassed when driving next to people in parking lots. another reason to get a louder exhaust....

[AbidingDude]

I have just passed 1000 miles in my BRZ and have started noticing this sound as well. Seems to get worse. There is also a high-pitch ringing sound now, the last two days, when idling. When applying a little throttle, it goes away but comes back when idling. This is when the engine is warm. It's been 95-106F the last ten days where I live so I suppose it could have something to do with the engine running really hot. Turning off A/C doesn't seem to make a difference.
When the engine is cold, there seems to be a whole slew of bad noises from the engine. Is that normal for a Subaru Boxer? This is my first Subaru.
I should also add that I have been gentle on throttle and revving the whole time. Plan to be gentle on it until the first oil change.

[denkigrve]

Originally Posted by AbidingDude

I have just passed 1000 miles in my BRZ and have started noticing this sound as well. Seems to get worse. There is also a high-pitch ringing sound now, the last two days, when idling. When applying a little throttle, it goes away but comes back when idling. This is when the engine is warm. It's been 95-106F the last ten days where I live so I suppose it could have something to do with the engine running really hot. Turning off A/C doesn't seem to make a difference.
When the engine is cold, there seems to be a whole slew of bad noises from the engine. Is that normal for a Subaru Boxer? This is my first Subaru.

There are multiple threads on the chirping sound. That's most likely the idler pulley. Some folks have their car in for service, and we're waiting for updates on that.

In terms of noise, my WRX is noisy. Has been since day 1. Some stuff still makes me wonder, but time will tell. The best thing you can do if you're concerned is to call your dealership. You're under warranty, so if there is an issue it's best to use that rather than wait and pay out of pocket.

[McFly]

I've heard this noise in mine.

[Sigh-on-Rice]

Originally Posted by prest1ge

noticed the sound since day one. sounds REALLY ugly IMO and makes me feel a little embarrassed when driving next to people in parking lots. another reason to get a louder exhaust....

I feel a little embarrassed too especially in a covered parking lot.

[ultra]

Originally Posted by uspspro

I noticed that the sound tube resonator box can easily rattle against the intake manifold.

It has soft rubber mounting.

Any clue how to fix it, or where it rubs?

I'm gonna check on it later tonight.

[7thgear]

anyone here with an aftermarket manifold experiencing same rattling?

Could be the heatshields doing their thing, i'm thinking of unbolting mine before winter sets in, then i'll avoid a big rusty mess 2-3 years down the line.

[Sigh-on-Rice]

Originally Posted by ultra

Any clue how to fix it, or where it rubs?

I'm gonna check on it later tonight.

Originally Posted by 7thgear

anyone here with an aftermarket manifold experiencing same rattling?

Could be the heatshields doing their thing, i'm thinking of unbolting mine before winter sets in, then i'll avoid a big rusty mess 2-3 years down the line.

I'm thinking this noise is NOT coming from the sound tube resonator box or the heat shield. If it is, then it should make the noise on any gear. The noise happens only in 1st, 2nd, or 3rd gear. The noise coming from clutch makes sense because it makes noise only in certain gears. I'm thinking it might be because of triple cone synchro. If anyone knows, that will be nice to know when explaining to people who asks what that noise is (I've had 2 passengers asking about the noise).

[7thgear]

Originally Posted by Sigh-on-Rice

I'm thinking this noise is NOT coming from the sound tube resonator box or the heat shield. If it is, then it should make the noise on any gear. The noise happens only in 1st, 2nd, or 3rd gear. The noise coming from clutch makes sense because it makes noise only in certain gears. I'm thinking it might be because of triple cone synchro. If anyone knows, that will be nice to know when explaining to people who asks what that noise is (I've had 2 passengers asking about the noise).

only first 3 gears?

so if slow down to 10-15 km/h in 5th gear and then floor it, it doesn't make that noise?

[Hanzo]

I sometimes get this metallic clatter noise in the morning when I accelerate and sometimes get some vibration noise from my gear shifter. I'm hoping these are all related to the chirping noise if it's ever fixed.

[Sigh-on-Rice]

Originally Posted by 7thgear

only first 3 gears?

so if slow down to 10-15 km/h in 5th gear and then floor it, it doesn't make that noise?

Yes, only first 3 gears. And this thread is about during deceleration (engine braking). I'm not talking about the noise it would make if you accelerate in too low RPM. I know that's normal.

[ultra]

Wonder what kind of clutch & flywheel they're sung in these cars...reminds ,e a bit of the twin plate rattle in my Evo...except that twin plates usually only rattle when you have the clutch pushed in.

And no, I'm not suggesting that these cars use a twin plate clutch. The sound descriptions are somewhat similar is all.

[ultra]

Here's something weird - my dash rattle wasn't there this morning!

At least not for 15 minutes.

I let the car warm up for 5 minutes (smoke break) then drove to work in silence. It only started again after about 15 minutes on the road, so now I'm confused.

What kind of dash rattle would only show up under acceleration once the car's hot (or warmed up)?

I was thinking that it's triggered by some kind of harmonic resonance, but bringing engine temp into the equation means that I am baffled right now. :P

I'm going to try and dump some toluene into the tank to see if it might be knock/ping related, then will remove the noise generator and check the heatshields on the exhaust.

That way I suppose I'll know that it's either something weird in the dash, or the injectors/valves, or maybe the transmission/clutch.

Engine oil might be a factor too - I think the OEM is 0w20 but it's around 40-50 Celsius outside here in Dubai so I'm thinking that the oil might just be too thin?