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2008 Forester X (10th AE) Automatic
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8 Posts
Discussion Starter · #1 ·
Hi everyone,

Since a few weeks, I have a knocking sound under the car, (Forester '08 auto). The sound comes approximately from the center of the car.
At very low speed, I can hear it while driving over bumps.

Don't know if it's related, but at high speed (~115Km/h), the whole car vibrates (do not feel it in the steering wheel). The vibration does not occur at ~100Km/h).

Any idea what could be the problem?

Thank you much for your help!
 

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Premium Member
2008 Forester X Premium 5MT
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8,064 Posts
Take a look at the driveshaft. The rubber on the center bearing gets dry rotted as they age, and our '08 are getting there. Also take a look at the u-joints on the driveshaft.

Per Subaru the center bearing and the driveshaft are not serviceable and must be replaced as a whole. However it is possible to replace the non-serviceable staked-in u-joints and the center bearing is available from the aftermarket world.

Just a place to start looking(the driveshaft) and a heads up on what to expect if it is the culprit.
 

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Registered
2008 Forester X (10th AE) Automatic
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8 Posts
Discussion Starter · #4 ·
Take a look at the driveshaft. The rubber on the center bearing gets dry rotted as they age, and our '08 are getting there. Also take a look at the u-joints on the driveshaft.

Per Subaru the center bearing and the driveshaft are not serviceable and must be replaced as a whole. However it is possible to replace the non-serviceable staked-in u-joints and the center bearing is available from the aftermarket world.

Just a place to start looking(the driveshaft) and a heads up on what to expect if it is the culprit.
Hi again,

Car has only 108000Km (68K miles) and already had an engine problem (dropped valve guide at 94000Km - thankfully under warranty) (engine now knocks like a diesel for the first 10 minutes when cold outside since) and now, possible drive shaft replacement. I was expected to keep that car for a long time (at least 10 years), but now, I'm getting seriously ticked off :icon_mad:!

Have a 15 years old Camry with over 210000Km on it and never have any drive train issue (just regular maintenance).

What should I expect in the up comings years?

Thank you very much for your help!
 

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Premium Member
2008 Forester X Premium 5MT
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8,064 Posts
One thing people need to keep in mind is that cars, all cars from any manufacture are a crap shoot. They are a mechanical item, a assembly of parts and assemblies built by people.

Mechanically speaking your 15 year old Camry is a simpler car with only two drive wheels. AWD adds a few components increasing the odds of having an issue. For a AWD car Subarus are about as simple as it gets.

As I said the driveshaft is only a place to start looking.

As to the previous valve guide repair and it knocking when cold now after the fact. That is something that should have been forced with Subaru and or the dealer as it may go to show not every thing was repaired properly... pressed in valve guides can migrate in some engines, it isn't limited to Subaru.
 

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Administrator
2004 Forester XT Premium 4EAT
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29,432 Posts
Could also be something as simple as the rear diff outrigger bushings being dried up and causing the knocking sound. Kartboy makes some nice, durable replacements.
 

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Registered
2008 Forester X (10th AE) Automatic
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8 Posts
Discussion Starter · #7 ·
One thing people need to keep in mind is that cars, all cars from any manufacture are a crap shoot. They are a mechanical item, a assembly of parts and assemblies built by people.

Mechanically speaking your 15 year old Camry is a simpler car with only two drive wheels. AWD adds a few components increasing the odds of having an issue. For a AWD car Subarus are about as simple as it gets.

As I said the driveshaft is only a place to start looking.

As to the previous valve guide repair and it knocking when cold now after the fact. That is something that should have been forced with Subaru and or the dealer as it may go to show not every thing was repaired properly... pressed in valve guides can migrate in some engines, it isn't limited to Subaru.
For the engine knock, I brought it back to the dealer and all they had to say is "normal noise" for the age of the engine... I've been told that this is called engine slap. Should I be worried?

Thanks again!
 

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Registered
2008 Forester X (10th AE) Automatic
Joined
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8 Posts
Discussion Starter · #8 ·
Could also be something as simple as the rear diff outrigger bushings being dried up and causing the knocking sound. Kartboy makes some nice, durable replacements.
Thank you! Will also mention that to my mechanic.
 
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