Technical Weird knocking

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Technical Weird knocking

vvsalmin

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Jun 23, 2025
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Location
Finland
Any ideas what could cause this weird knocking sound.. It has gotten quite bad. It is always present when car is started cold and it goes away when engine has ran about 2 minutes. Knocking is so bad you can hear it clearly when you start driving the car.



I have checked the valve clearings and those were in specs. Car has been driven 160000km.
 
Model
Grande Punto 1.4L 8V
Year
2007
Mileage
160000
So difficult to tell without being there, but, it sounds like an exhaust blow to me. Most likely from where the manifold bolts to the head. Get yourself a length of flexible tubing, something like windscreen washer tubing or maybe something with a wee bit bigger bore size. stick one end in your ear and move the other end around the interface between the head and manifold. When you get the end of the tube over where the noise is coming from it'll be loud in your ear. Be careful not to get the end of the tube caught up in anything moving, like the fan belt pulleys.
 
Nothing "weird".
Exhaust manifold, typical sound (and goes away as it heats up, as fast as 30-60 seconds and you think it's "OK" = it's NOT).
Example repair (demonstration of most common mistakes, like drilling off center etc.).
Non-English forum: https://fiatpunto.com.pl/topic61924.html
Studs pop when the manifold is warped. You must address this too (replacing studs is not enough).

Exhaust leak is still there, even if you can't hear it after warming up. It will spoil the lambda/cat. performance (bad emissions).
System is that sensitive.
 
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So difficult to tell without being there, but, it sounds like an exhaust blow to me. Get yourself a length of flexible tubing, something like windscreen washer tubing or maybe something with a wee bit bigger bore size. stick one end in your ear and move the other end around the interface between the head and manifold.

Aluminium foil cardboard core works

Has this block got Hydraulic tappets/lifters? :unsure:
 
Lame question. Clearly, this is 8V unit, they all have manual valve adjustment (shims). FIRE 16V are hydraulic.
Plus looks like 1,2 (in Grande they don't have VVT, so another source of noise is out of the equation).
 
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sounds like you are quite certain about the reason .. nice ...

so I need to remove the manifold, resurface it and replace broken studs ...
 
sounds like you are quite certain about the reason .. nice ...

so I need to remove the manifold, resurface it and replace broken studs ...
You can never be absolutely sure about a noise relayed through cheap laptop speakers, but I'm feeling confident about this one having heard manifold blows on quite a number of engines in my life. This one seems quite loud so may have been blowing for some time. When you get the manifold off - and good luck with the studs - take a very careful look at the mating faces on the head and manifold. If it's been blowing for a while, the very hot gasses can erode and damage the flatness of the mating faces which might make it very difficult to then achieve a good seal. Don't discount that the manifold itself may be cracked or distorted. Everything needs to be carefully checked.
 
Try being nice for a change :rolleyes: I've put you on ignore so don't bother responding
Try being informed (in case of FIRE family, which is 40 years old)!
@GrandePunto PL I'm not trying to "pick a fight" with you and wonder if your choice of wording in replies might be due to English not being your first language thus causing misunderstanding? However you do come across as confrontational sometimes.

You obviously are quite knowledgeable regarding our much loved wee cars, but many others on here do not have that advantage and so often ask questions which might seem "silly" or even ridiculous. I personally, welcome this as it gives us the opportunity to pass on our knowledge to those less well informed and often starts a conversation in which I learn something I didn't previously know.

As my youngest boy would probably say - "just chill out man"!
 
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@GrandePunto PL I'm not trying to "pick a fight" with you and wonder if your choice of wording in replies might be due to English not being your first language? However you do come across as confrontational sometimes.

You obviously are quite knowledgeable regarding our much loved wee cars, but many others on here do not have that advantage and so often ask questions which might seem "silly" or even ridiculous. I personally, welcome this as it gives us the opportunity to pass on our knowledge to those less well informed and often starts a conversation in which I learn something I didn't previously know.

As my youngest boy would probably say - "just chill out man"!
Also, good to remember that this is a 'users forum' and therefore, said 'users' are of all abilities and knowledge. Some, have a vast amount of previous working with cars or mechanical items, some have little or none, and therefore are asking for some sort of help, and, according to their abilities, will obviously be requiring different levels of help.
Those of us who are shall we say, 'mechanically minded' might tend to forget how some that have little or no mechanical knowledge seem to need more 'gentle' help that others who have better abilities. I always try to remember that I was once like that, and only gained a lot of what I know from college courses, or working with more skilled people, who were happy to share and explain to me. I have 5 C&G's in Engineering, and an ONC as well, but still try to tailor any help to the ability of the person asking for help, and ensuring they are happy with that. Years ago, I was designated as a 'mentor' in my engineering job, and was expected to give help to apprentices who were nearing the end of their time, but working on the shop floor, to help them when they needed it. Much patience and sensitivity needed to deal with those who were all of different mental and physical abilities. Some learnt quicker than others, some needed a bit more help in explaining solutions, and thought processes.
One of my tutors at college used to say, 'remember how you felt when first spent a day on the shop floor, and try to help those who are now in that situation. Pass on your knowledge, as that's the most precious thing in the world'
 
Also, good to remember that this is a 'users forum' and therefore, said 'users' are of all abilities and knowledge. Some, have a vast amount of previous working with cars or mechanical items, some have little or none, and therefore are asking for some sort of help, and, according to their abilities, will obviously be requiring different levels of help.
Those of us who are shall we say, 'mechanically minded' might tend to forget how some that have little or no mechanical knowledge seem to need more 'gentle' help that others who have better abilities. I always try to remember that I was once like that, and only gained a lot of what I know from college courses, or working with more skilled people, who were happy to share and explain to me. I have 5 C&G's in Engineering, and an ONC as well, but still try to tailor any help to the ability of the person asking for help, and ensuring they are happy with that. Years ago, I was designated as a 'mentor' in my engineering job, and was expected to give help to apprentices who were nearing the end of their time, but working on the shop floor, to help them when they needed it. Much patience and sensitivity needed to deal with those who were all of different mental and physical abilities. Some learnt quicker than others, some needed a bit more help in explaining solutions, and thought processes.
One of my tutors at college used to say, 'remember how you felt when first spent a day on the shop floor, and try to help those who are now in that situation. Pass on your knowledge, as that's the most precious thing in the world'
I remember my Dad saying to me "If only I could magically transpose all that's in my brain into yours son" - but, on reflection, maybe it's just as well he couldn't!
 
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