Rattling noise under the hood during engine braking at low RPM

[Sigh-on-Rice]

This is for manual transmission during deceleration.
I notice there is a "jar of marbles" sound during engine braking (deceleration).
It starts at about 2200 RPM and ends at about 1200 RPM.
It makes the noise only in 1st, 2nd, and 3rd gears. Not in 4th and above.
Does anyone else notice this noise?

[Sigh-on-Rice]

I forgot to mention one thing. I have a manual transmission.

But no one else hear this noise? I'm starting to be worried if my car is the only car that makes this noise.

[Koji_Online]

In my honest opinion it may just be more vibrations due to the engine stressing at low rpm with gear load; I suggest clutch in at 2k rpm or downshift if you have to speed up again.
I downshift naturally any time I slow down, but it just feels unnatural & harsh to let my rpm dip below 2k; when not spirited driving (or racing) I actually only downshift to as far down as 3rd then clutch in at 2k RPM; not trying to mash synchros, I do not go down to second when doing normal street slowdowns becuase the 2nd gear synchros seem stressed if not downshifting from a higher range RPM

[serialk11r]

Originally Posted by Koji_Online

In my honest opinion it may just be more vibrations due to the engine stressing at low rpm with gear load; I suggest clutch in at 2k rpm or downshift if you have to speed up again.
I downshift naturally any time I slow down, but it just feels unnatural & harsh to let my rpm dip below 2k

Maybe it's the transmission rather than the engine, because automatic transmissions run the engine all the way down to 1200rpm or lower before downshifting and no one really talks about them having the vibration issues (locked up).

[Boosted2.0]

I havent ever noticed that, but I will keep an ear open tonight. Are you using engine braking only, or engine braking AND foot brake when you hear it?

[Sigh-on-Rice]

Originally Posted by Boosted2.0

I havent ever noticed that, but I will keep an ear open tonight. Are you using engine braking only, or engine braking AND foot brake when you hear it?

I'm using engine braking only. If I use foot brake too, then the RPM would go down too fast to hear this noise. It's hardly noticeable in 1st or 3rd gear. 2nd is the best gear to hear this noise. I don't hear it on 4th to 6th gear. The windows need to be closed, otherwise the engine noise coming from outside is louder than this noise, so you won't hear it. It's loudest at around 1600 RPM.

[Sigh-on-Rice]

Originally Posted by Koji_Online

In my honest opinion it may just be more vibrations due to the engine stressing at low rpm with gear load; I suggest clutch in at 2k rpm or downshift if you have to speed up again.
I downshift naturally any time I slow down, but it just feels unnatural & harsh to let my rpm dip below 2k; when not spirited driving (or racing) I actually only downshift to as far down as 3rd then clutch in at 2k RPM; not trying to mash synchros, I do not go down to second when doing normal street slowdowns becuase the 2nd gear synchros seem stressed if not downshifting from a higher range RPM

That makes sense. But the thing is, all the Toyota cars that I had didn't make this noise. I usually don't step on the clutch during engine braking until 1000 RPM and I've been doing that for 7 years. Maybe this noise is a Subaru thing and is normal, but I'm just curious if anyone else is hearing this noise too.

[DYOLF26]

It's very possible it's just a heat shield. Check the heat shields around the engine and exhaust. Or even easier, just bring it to a dealership, It's not going to cost you anything but maybe 30 mins of your time and they will be able to have someone looking for the noise under the car while it is running since it will be on a lift.

[uspspro]

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

It has soft rubber mounting.

[Sigh-on-Rice]

Since it only happens when it's in 1st, 2nd, or 3rd gear, I'm wondering if this noise has something to do with the triple cone synchro.

[Sigh-on-Rice]

Anyone notice this noise yet?

[Nate219BRZ]

Yeah we had a discussion going on in the new manual drivers Q & A about this noise.

[Sigh-on-Rice]

Originally Posted by Nate219BRZ

Yeah we had a discussion going on in the new manual drivers Q & A about this noise.

Yep, I was part of that discussion too. I'm wondering if anyone else is experiencing this noise during deceleration (not acceleration).

[eriktherod]

I've heard the noise. I've been able to get it to occur when being feathery in the throttle at low speeds in first/second gear (say below 2k rpm). I'm used to riding second gear sort of low (6-10mph) while in parking lots looking for a spot. When I give it a little gas, I typically hear that noise. Pretty sure it normal.

[Sigh-on-Rice]

Originally Posted by eriktherod

I've heard the noise. I've been able to get it to occur when being feathery in the throttle at low speeds in first/second gear (say below 2k rpm). I'm used to riding second gear sort of low (6-10mph) while in parking lots looking for a spot. When I give it a little gas, I typically hear that noise. Pretty sure it normal.

Yep, I know the noise you're talking about During acceleration at low RPM is normal because I get that noise from every car I drove. The noise I'm talking about in this thread is specifically during deceleration (engine braking). Say I'm traveling at 20 mph and down shift to 2nd gear. The RPM goes down as the car slows down. When the RPM goes below 2000 RPM, it starts to make noise that sounds like a metal plate rattling against another metal plate.

[eriktherod]

I'll check it out tomorrow!

[Sigh-on-Rice]

Originally Posted by eriktherod

I'll check it out tomorrow!

Any chance to check it out?

[eriktherod]

I tried and it felt like the same sound I was used to.. I didn't noticed anything other than the typical noise I expected.

[Sigh-on-Rice]

Originally Posted by eriktherod

I tried and it felt like the same sound I was used to.. I didn't noticed anything other than the typical noise I expected.

Thanks for checking. I guess mine has a problem. I hope the noise goes away after I put some more miles on it.

[#87]

Have you had this sound just after the downshift? I think I heard it once or twice a chattering type sound but I attributed it to a bad shift on my part, not exactly sure what triggered it.

[Sigh-on-Rice]

Originally Posted by dhenz

I also have the same problem, the rattling occurs between 1200 to 1600rpm, I tried to replace spark plugs but nothing happened... any ideas would be great. thanks

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car parts/oem parts
performance parts/replacement parts

Are you hearing this noise while you're decelerating in gear? And it only happens on 1st, 2nd, and 3rd gear, but not in 4th gear?

[Pscylo]

I only get the grainy noise in 1st/2nd at low rpm because of the clutch thats used, if I am in any other gear and drop low enough I downshift out of habit, so I never heard it in 3rd.

Side note its all over the forum, should have just been a sticky by now that explains the expected noises so people won't repeatedly ask about them. Not saying this guy has the same noise, but it made me think about it.