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Discussion Starter #1
Hi peeps. Have a problem with my wife's 307.

A strange knocking sound has presented itself. The sound is very audible when the car is idling. When the revs increase I'm not sure if the sound is there, mainly due to engine noise.

The knocking sound seems to be coming from the timing belt area or behind the timing belt area.

The knocking is timed perfectly with every revolution (At least it sounds that way to me).

It sounds very similar to this:

https://www.youtube.com/watch?v=5KV4RdsfyS8

I usually do all the repairs and servicing on our cars but need to identify the cause of the noise to know if it's something I can handle.

Early last year I fitted a new timing belt, water pump etc. but it all seems pretty sound.

Would welcome any advice or suggestions.
 

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Discussion Starter #3
That may be the same noise. Hard to tell but it's a possibility as the noise could be coming from this area.

How do I identify if this is indeed the problem?
I would think the crank shaft pulley is attached to the crank shaft, so what is making the noise? Is it the bearing or the pulley itself?
 

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I believe the pulley is rubber damped IE two parts bonded together which if the bonding gives way causes this

A Physical look is the best way to check though
 

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Discussion Starter #5
Thanks for the responses.
I've removed everything including the timing belt to expose all the parts I thought might be causing the noise.

Please see attached. Everything looks good to me;
The crank shaft pulley appears to be ok. When I push it around with my hands I don't feel any movement. There is a rubber damper in it but I think it is ok.

The timing belt tensioner seems to be ok, the bearing is firm but turns easily and has no play.

One thing I did notice was the water pump; When I turn the gear for the water pump there is no play but it does not turn freely. There is a little resistance from the seal and a kind of 'squelching' sound/feeling when turning it. Maybe this is normal assuming there is a seal on this shaft and coolant still inside the engine.

Is there anything I should be checking while I have this all apart?
 

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Not sure I would have stripped off the timing belt As I think if removed it is best to renew ,,

with the timing belt on did you try the engine for a short time to see if the noise had gone with the Aux belt off ? I usually try to get a socket extension or long screwdriver to use like a stethoscope when trying to trace odd noises or even a plastic hoover pipe

Last water pump I replaced on a car the spindle rotated without any stiffness felt from the new pump (whilst off the car ) but was changed due to a massive leak through a seal
 

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Discussion Starter #7
Yep.. Started the engine with the aux belt off. Noise was still there.

I used the old screw driver as a stethoscope and had some strange results; When placed on the engine head itself while the engine was running I couldn't hear the noise through it. But when placed on the engine mount above the timing belt I could hear the noise clearly.

Another thing; I took the car down to work today so a colleague could have a listen to the noise. He said the timing belt looked a little loose to him and looked a bit older than the year which it's been in there.

I'm thinking of replacing the timing belt. Also going to take another look at the water pump tomorrow.
 

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well if you are changing the belt anyway do the pump also As its driven by the cambelt If it fails it would take the belt with it False Economy not to really
 

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Discussion Starter #9
Got a new timing belt kit and fitted it today.
Once it was all fitted and before fitting the aux belt I started the car and the noise was not there. I fitted the aux belt and started the car... The damn noise was there again. It was getting late so I fitted the engine mountings and everything back together.

Yesterday before dismantling everything I did try with the aux belt removed and I near certain the noise was there... or I'm loosing my mind.

So €90 later and a lot of wasted time I'm back to square one.

Tomorrow evening I will remove the aux belt again and see if the noise is still there.

Maybe the crankshaft pulley is the culprit???
 

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I believe the pulley is rubber damped IE two parts bonded together which if the bonding gives way causes this

A Physical look is the best way to check though
I believe the rubber goes soft with age and the torsional stress makes the pulley outer rotate laterally in a sort of jerking motion If you can make sense of that
 
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Got a new timing belt kit and fitted it today.
Once it was all fitted and before fitting the aux belt I started the car and the noise was not there. I fitted the aux belt and started the car... The damn noise was there again. It was getting late so I fitted the engine mountings and everything back together.

Yesterday before dismantling everything I did try with the aux belt removed and I near certain the noise was there... or I'm loosing my mind.

So €90 later and a lot of wasted time I'm back to square one.

Tomorrow evening I will remove the aux belt again and see if the noise is still there.

Maybe the crankshaft pulley is the culprit???
What did you get the with cambelt kit? There is usually a pully for the aux belt, did you change this?

Plus changing cambelt is hardly a waste of time. Your covered now for next 90K or 10 years.
 

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Discussion Starter #12
Got home this evening and took the aux belt off. Started the car and the noise is there.

I'm wondering if it could be something electric behind the engine or even something in the fuel intake or something. I read something on the internet about the butterflies getting stuck.
 
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Got home this evening and took the aux belt off. Started the car and the noise is there.

I'm wondering if it could be something electric behind the engine or even something in the fuel intake or something. I read something on the internet about the butterflies getting stuck.
any chance of getting a recording of the noise on your car?
 

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Discussion Starter #16
I took the car to a mechanic at the weekend. He had a listen to the engine using a mechanics stethoscope.
All the noise was coming from the water pump area.
I bought and fitted a new water pump. The noise is gone, problem sorted. Don't know how this happened as the water pump was not even a year old but glad it's sorted.
Thanks for the comments peeps.
 
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I took the car to a mechanic at the weekend. He had a listen to the engine using a mechanics stethoscope.
All the noise was coming from the water pump area.
I bought and fitted a new water pump. The noise is gone, problem sorted. Don't know how this happened as the water pump was not even a year old but glad it's sorted.
Thanks for the comments peeps.
Wonderful news :D
 
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