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04-24-2018, 03:21 AM | #1 |
Scooby Newbie
Member#: 482206
Join Date: Feb 2018
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08 2.5L Impreza buzzing when decelerating
Hi all,
I have a question about a specific buzzing sound that occurs in my 2008 Impreza 2.5L. It only occurs between the 3.0k and 3.2k RPM, either accelerating or decelerating. The sound occurs in every gear, including neutral at a standstill. I have heard people having heat shield rattles but this sounds more high pitched than any of the heat shields I've listened to. It seems to me to have to do with the engine vibrating at a certain frequency that it causes something else to buzz loudly for a moment, but I am not sure. Any insight on the matter will be much appreciated!
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04-26-2018, 10:55 AM | #2 |
Scooby Guru
Member#: 141373
Join Date: Feb 2007
Chapter/Region:
E. Canada
Location: Quebec, QC
Vehicle:2022 Crosstrek Sport 6MT |
There are a lot of things that start to rattle after 10 years. Heat shields are the main suspect, and they can make an entire symphony of noises. It's nearly impossible to pinpoint the source based on the decription alone. Check where it comes from. Underneath the engine? transmission? Near a specific belt/pulley?
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04-26-2018, 11:27 AM | #3 |
Scooby Newbie
Member#: 459449
Join Date: Dec 2016
Location: Minnesnowta
Vehicle:2017 WRX Lapis Blue Pearl |
I had this happen on my 08 impreza(this was in 2012) and low and behold it was the heat shield on the exhaust. A couple metal clamps around it solved the problem, but as Bluefoton said, its an old car and there could be a number of culprits.
Best bet is to have a buddy try to pinpoint it while the car is parked and you manipulate the throttle to recreate the noise. |
04-27-2018, 09:43 AM | #4 |
NASIOC Supporter
Member#: 30669
Join Date: Dec 2002
Chapter/Region:
Tri-State
Location: USA, North NJ, 07456
Vehicle:1998 Legacy 2.5GT Silver Sleeper BK, 5MT |
I usually jack the car up, get under it, and bang on things with a rubber mallet. That is a fast way to find rattles and buzzes, especially in/on the exhaust.
Start at the front, work your way back. |
06-17-2018, 02:14 AM | #5 |
Scooby Newbie
Member#: 482206
Join Date: Feb 2018
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So sorry to take so long to respond! So I jacked the car up and had a helper recreate the buzzing by putting the car at around 3k RPM. I pressed on a few pieces of the exhaust, which seemed to be where the resonation was coming from, but not find the source. I put a few hose clamps around the heat shield (or what I thought was the heat shield) to no avail.
The buzz definitely goes through the exhaust, but it appears to be originating from the very front of the exhaust; maybe not even the the exhaust at all. Another thing that I noticed today is that if I am in a gear and am decelerating while pushing the shifter into gear more the vibration/buzzing is a little softer. If that didn't make sense, I mean that I am in second gear, decelerating, no clutch engagement, and am pulling back on the shifter with a little force. I will take the car to an exhaust shop on Monday to see what they think. Final points: do you think that a bad motor mount, transmission mount, or pitch stop mount could cause weird symptoms like this? The vibration is getting worse. In fact, now if I am in the 3k-3.2k range with the AC compressor on, that makes a weird ass humming noise too. It still drives and shifts great, but I am getting very annoyed |
06-22-2018, 12:56 PM | #6 |
Scooby Newbie
Member#: 255947
Join Date: Aug 2010
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you could get one of those stethoscope things the doctors use. I bought one off amazon to help me locate some noises..Not perfect but it helped.
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