Vibration at ~4500 - 4700 RPM

[HamburgerSushi]

Hello friends,

I've had the car since March and first noticed on quiet mornings with no music (and then in every situation) a metallic rattle. Here are its features:

- Loudest 4500 - 4700 RPM -> crescendo-decrescendo in this range both when accelerating through it and decelerating through it, loudest accelerating
- Louder with more throttle
- Occurs when in neutral (I'm pretty sure)
- When applying throttle at ~3200 RPM, a similar (potentially the same) noise is elicited for ~1 second and then goes away
- It subjectively sounds like it is coming from behind the dash at a 10-15 degree angle to the right from the driver's seat (left hand drive car)

I have some installed bushings which may have brought this on, although I'm pretty sure this noise has been with me since the car was new. Here is the list of bushings:

- Perrin shifter carrier bushing
- Perrin steering lockout bushings
- Whiteline transmission mount insert bushing

Other than that:

- Crawford Performance air-oil separator

Sound generator is half-deleted (tube connecting to intake is removed and remaining hole plugged) - will complete the deletion today - 3/4" plug is ready
As a test, I secured the dipstick with a zip-tie (temporarily) as it seems to vibrate at the same frequency as the noise I am describing with blunt trauma - did not fix the issue

Heat shields around exhaust manifold feel tight

I've got the 2017 with the aluminum intake manifold

I've also checked the bolts under the car and they are all tight - don't know where to go from here.

Any ideas folks? Anything I haven't checked? Took it to a dealer - they couldn't find anything and were kind enough to not charge me for the time the master tech spent looking for the issue.



Here is a pic of my car and engine bay for lulz:




Of course I will post updates as I find or don't find things. I hope this post helps! I do not like vibrations and like to eliminate them with extreme prejudice.

[BRZnut]

BRZ looks great....can you post a sound clip of the rattle?

[IDFWU 420]

Try getting a good sound recording of the problem so we can have a good understanding of what you're talking about.

[steve99]

Is your car tuned, a lot of tunes for stock header or EL header will have a raspy noise between 3000-4500


See here.

http://www.ft86club.com/forums/showthread.php?t=59475

[HamburgerSushi]

The car is not yet tuned. Hopefully that'll change soon.

As for the video, that's a good idea. Here it is:

I can hear the noise even on my phone speaker - I imagine it will be very clear with headphones.

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[IDFWU 420]

Has the noise been there before you bought the car, but only just noticed it now or did it suddenly just started happening?

That rattle sounds normal to me.

[HamburgerSushi]

Originally Posted by IDFWU 420

Has the noise been there before you bought the car, but only just noticed it now or did it suddenly just started happening?

That rattle sounds normal to me.

It's been there the whole time from my memory. It may have gotten worse with my installation of the bushings listed in the first post.

I don't believe it sounds normal because of its nature as a metallic rattle.


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[DaBoBo21]

You may want to have all of the heatshields checked again. The heatshield on my front pipe looked and felt snug, but it wasn't. I had a metallic rattle from the time I took it off the lot until I took it to the dealership in April (w/ approx. 6000 miles on it). It was like you described, rattle when throttle applied and once the engine/ trans settled out it would go away. It happened in neutral, as well. Dealership replaced it under warranty and since then I have not had any rattling.

[HamburgerSushi]

Originally Posted by DaBoBo21

You may want to have all of the heatshields checked again. The heatshield on my front pipe looked and felt snug, but it wasn't. I had a metallic rattle from the time I took it off the lot until I took it to the dealership in April (w/ approx. 6000 miles on it). It was like you described, rattle when throttle applied and once the engine/ trans settled out it would go away. It happened in neutral, as well. Dealership replaced it under warranty and since then I have not had any rattling.

Thanks for the input!
This is my suspicion as well.

If this is the case:
Do you think it's worth reversing all my little bushings for this replacement or do you think it would be OK to just wrap the exhaust manifold in DEI titanium?

Thank you


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[DaBoBo21]

Originally Posted by HamburgerSushi

Thanks for the input!
This is my suspicion as well.

If this is the case:
Do you think it's worth reversing all my little bushings for this replacement or do you think it would be OK to just wrap the exhaust manifold in DEI titanium?

Thank you

I wouldn't do anything with the bushings as they probably aren't the issue. You could delete the headshields and do the wrap, but it would be unnecessary in my opinion. If it were me, I'd have the dealership inspect from your headers all the way back to the muffler and go from there. You have the warranty, so I'd use it and not spend your money on stuff that may not fix the issue.

[HamburgerSushi]

Originally Posted by DaBoBo21

I wouldn't do anything with the bushings as they probably aren't the issue. You could delete the headshields and do the wrap, but it would be unnecessary in my opinion. If it were me, I'd have the dealership inspect from your headers all the way back to the muffler and go from there. You have the warranty, so I'd use it and not spend your money on stuff that may not fix the issue.

Dealer stated that Subaru would require the car to be stock for such investigations. Theoretically, the bushings could transmit more vibrations and result in amplification.

I might try again if I am sure a heat shield is the cause. We shall see.

Thanks for the input!
Please continue posting suggestions in the meantime folks.


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[DaBoBo21]

Originally Posted by HamburgerSushi

Dealer stated that Subaru would require the car to be stock for such investigations. Theoretically, the bushings could transmit more vibrations and result in amplification.

I might try again if I am sure a heat shield is the cause. We shall see.

Thanks for the input!
Please continue posting suggestions in the meantime folks.

Understandable. Although, I had an aftermarket catback and the MTEC clutch return spring installed and they still did the work on mine. As long as you can prove it's a faulty part on Subaru, then they'll do the work. Especially since this is something you've heard since taking the car off the lot. I wouldn't mention any modifications unless a TECHNICIAN asks you.

Good luck to you!

[Joon525]

Are there signs of your Crawford air/oil separator hitting your hood?
I had one, put it on and noticed it was really high. So I put a little stick on foam padding on top of it upside down and closed the hood and instantly saw it was touching (it stuck to the hood). I looked even more closely at the top of the air/oil separator and could see that there was evidence of it touching (I bought it used).
So just to rule it out, check that.

Edit: Also...
http://www.ft86club.com/forums/showp...95&postcount=7

[HamburgerSushi]

Originally Posted by Joon525

Are there signs of your Crawford air/oil separator hitting your hood?
I had one, put it on and noticed it was really high. So I put a little stick on foam padding on top of it upside down and closed the hood and instantly saw it was touching (it stuck to the hood). I looked even more closely at the top of the air/oil separator and could see that there was evidence of it touching (I bought it used).
So just to rule it out, check that.

Edit: Also...
http://www.ft86club.com/forums/showp...95&postcount=7

Well I'll be damned - here is the top of my Crawford Air-Oil Separator:

Here is my hood - can't find any abrasions:


I don't know if this is the culprit quite yet. Let me take a trip to Home Depot and get some cushioning and see if the vibration goes away.

I'll keep you folks updated!


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