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Faint knocking, piston slap!
As I do with all second hand cars I buy I'm convinced the previous wanted to sell as the car was ready to explode. Never has been the case and I'm very technically minded but still sceptical!
I must strees this knocking noise is faint and I do generally have good hearing. Anyway my car has the usual piston slap from cold, although its barely that audible and seems to pretty much go away when up to temperature. Today tho I noticed that if I held the revs at around 1200RPM I got a slight knocking sound, when I say slight I mean slight, with the blower on No.2 you cant even hear it. Stuck my head under the bonnet and slowly raised the revs and couldn't hear anything untoward and certainly nothing like the faint knocking noise I got when sat in the drivers seat. I think I'm just being over cautious but thought someone might have experienced something similar! Cheers:thumb: |
Originally Posted by stualex
(Post 10595462)
As I do with all second hand cars I buy I'm convinced the previous wanted to sell as the car was ready to explode. Never has been the case and I'm very technically minded but still sceptical!
I must strees this knocking noise is faint and I do generally have good hearing. Anyway my car has the usual piston slap from cold, although its barely that audible and seems to pretty much go away when up to temperature. Today tho I noticed that if I held the revs at around 1200RPM I got a slight knocking sound, when I say slight I mean slight, with the blower on No.2 you cant even hear it. Stuck my head under the bonnet and slowly raised the revs and couldn't hear anything untoward and certainly nothing like the faint knocking noise I got when sat in the drivers seat. I think I'm just being over cautious but thought someone might have experienced something similar! Cheers:thumb: |
Is it worse when its warm? Unliely to be a lifter on a 1998, they are the solid type.
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It's hardly even noticeable when warm, I have to park in a silent place, turn off radio and fans, shut the windows then I can just about hear it at around 1200RPM if I concentrate hard enough.
I can't hear it with the window open and not from inside the engine bay. I'm used to the V6 on my old Mondeo which was silky smooth and quiet and I think I'm just being over cautious. Cheers for the comments tho. |
Subaru paranoia at its best! When I hear a stone flick up and hit the bottom of the car/exhaust its soooooooooooo hard not to stop to make sure something hasn't fallen off!
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One possibility is the cambelt tensioner. They can 'bounce' slightly against the stop. More noticable at lowish revs as the belt is trying to flap (for want of a better word!) due to the forces of the cams. Tends to smooth out at higher revs as the frequency of compressing the springs get higher.
JohnD |
Originally Posted by JohnD
(Post 10596701)
One possibility is the cambelt tensioner. They can 'bounce' slightly against the stop. More noticable at lowish revs as the belt is trying to flap (for want of a better word!) due to the forces of the cams. Tends to smooth out at higher revs as the frequency of compressing the springs get higher.
JohnD Cheers:thumb: |
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