spontaneous random knock (not engine knock)

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spontaneous random knock (not engine knock)

Postby Lib3rty.wagon » Sun Apr 05, 2020 10:15 pm

Hey im new here sorry if this isnt in the right place.

I have a 2005 Subaru Liberty 3.0R Spec B Wagon (if that helps)

im having a random knock that comes and goes. I can go drives without hearing it and others (like today for me) where it just wouldnt shut up. it sounds like its coming from the front left of the car. you'd think it would be suspention cause sometimes when its just a bumpy road it knocks alot but i just took it to my mechanic and just had a hefty bill replacing that side suspention bushings and transmount etc on the front left side (dont have the bill on me, might get it out later if needed) and after taking to the mechanic and getting the hefty bill the noise is still there (i know this mechanic closely, his not ripping me for what i know) does anyone have any idea on what this knock could be. on a side note when i turn sharp right ill get a loud snap/knock sometimes about the same as the random knock. maybe could this be steering rack related? idk im just guessing. if anyone could give any ideas or knows anything please let me know thanks. <3
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Re: spontaneous random knock (not engine knock)

Postby bigBADbenny » Mon Apr 06, 2020 10:10 am

Its a pity your mechanic fired the parts cannon before actually making a diagnosis.
I hope the parts were replaced on both sides.

I suggest a thorough search of related threads for successful resolutions as you’re not the first with the issue.

Yes, listing the exact parts replaced would be helpful.

Here’s a site specific search, with some keywords for you, just change the keywords as required till you narrow down your specifics, if these don’t suit.
https://www.google.com.au/search?biw=27 ... s-wiz-serp


And:

https://www.google.com.au/search?biw=27 ... s-wiz-serp

...
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Re: spontaneous random knock (not engine knock)

Postby bigBADbenny » Mon Apr 06, 2020 10:23 am

Since its a sharp, single sound (yes?)
I’d be putting the car on stands or a hoist and checking any ball joints for looseness.
Eg tie rod end, ball joint, sway bar links, top plate bearing, spring seats, wheel hub etc.
Check if the swaybar is moving laterally, it might need new bushes at the subframe.

A component that usually runs smoothly as a bearing but in your case is binding then letting go.

If say on stands, you can lift that wheel with a jack to replicate static ride height and turn the wheels with preload on the suspension.
Any alignment garage can do this too.

Its also possible to do up the strut top nut with the washer/mating surfaces out of line, causing looseness.
The whole top plate assy can wear out, eg the bearing and or the rubber nvh bushing as can the spring seats.
Another source of knocking is the grease in the strut body drying up causing rattling between the damper and the strut body.
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Re: spontaneous random knock (not engine knock)

Postby BillyCorgi » Mon Apr 06, 2020 11:35 am

Lib3rty.wagon wrote:Hey im new here sorry if this isnt in the right place.

I have a 2005 Subaru Liberty 3.0R Spec B Wagon (if that helps)

im having a random knock that comes and goes. I can go drives without hearing it and others (like today for me) where it just wouldnt shut up. it sounds like its coming from the front left of the car. you'd think it would be suspention cause sometimes when its just a bumpy road it knocks alot but i just took it to my mechanic and just had a hefty bill replacing that side suspention bushings and transmount etc on the front left side (dont have the bill on me, might get it out later if needed) and after taking to the mechanic and getting the hefty bill the noise is still there (i know this mechanic closely, his not ripping me for what i know) does anyone have any idea on what this knock could be. on a side note when i turn sharp right ill get a loud snap/knock sometimes about the same as the random knock. maybe could this be steering rack related? idk im just guessing. if anyone could give any ideas or knows anything please let me know thanks. <3


Someone I know had the top stud on the Bilstein Strut broken, maikng a knock sound.
But, if it were that it should have been obvious when the other parts were changed?
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