Cold Day + Cold Start, LOUD Knocking (Sound file included)

[Simon@SprayShack]

Hi all,

i have noticed on my 172 ph2 , if the temp outside is cold <0c (or around that) and i start the car from cold i get a really loud knocking and like a bag of loose bolts sound from the drivers side at the front of the car.

Once the car warms up this sound goes, and it also doesnt happen on milder days. It also seems to come and go if i turn the air con on / off on ocasion, which is odd.

I have a sound file (all be it crappy) here taken with my phone,

http://www.fullsystem.co.uk/Voice001.wav

Its an odd problem, car starts and runs fine, it doesnt sound like its coming from the engine or head, its like around the AUX belt area i would imagine or just behind the bumper.

After a few minutes running, no knocking.........

Any ideas?

Cheers,
Si

 

[Simon@SprayShack]

bump

 

[richy22]

Is that coming from the engine bay or from inside the car??

 

[Simon@SprayShack]

engine bay area, lower pulley area towards the front it sounds like. That sound file was taken with the bonnet closed, so its loud. It doesnt sound like the block itself, more like a pulley issue to me (Only when cold tho!)

 

[richy22]

Hmmm dunno! Some sort of piston slapping maybe??

 

[powey]

maybe the cold is shrinking the metal slightly and making the pulleys work harder?

 

[mark989]

sound sodd

 

[Simon@SprayShack]

sound sodd?

 

[Simon@SprayShack]

Surely if it was piston slap, the engine would run like a dog due to low compression......and burn tons of oil. Mine uses oil, but not excessively......

 

[Simon@SprayShack]

bump

 

[Willy]

I thought that was normal, my car does that all the time and goes. Thought it was just warming up