It's still knocking

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Aidris

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Good day gentlemen,
Either I'm being rickrolled by mechanics or I'm really unlucky. The deal is that I've rebuilt my s3 8p 2009. Cost over 4k €. New pistons, chains, tensioners. Literally everything new from engine block. Car drives smooth as butter. But the ding dong is that car still rattles when cold. To specify, after cold start settles down. Metal to metal. Dissapears when warm. Does anyone have any clue what could it be? Because soon I will identify as kilometers per second if the problem persists.. HELP!

EDIT: about the sound: rattle matches the revs. From idle to about 1.4k revs, then dissapears as you rev higher. Clutch in clutch out no difference. As car warms up the rattle becomes irrational, it knocks it does not then again until goes silent..
 
Last edited:
Alternator or a/c compressor pulleys loose or touching something?
 
Then how come the sound dissappear after some time? Anyways, will definitely look after it
 
Need to isolate anything outside the engine first before you start opening up the the engine itself. I would remove the auxiliary belts and start the engine to rule out the rotating parts.
Using a makeshift stethoscope may also pinpoint the noise. If you still can't find the cause of the noise then you would have to start looking inside the engine.
 
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SootySport said:
Need to isolate anything outside the engine first before you start opening up the the engine itself. I would remove the auxiliary belts and start the engine to rule out the rotating parts.
Using a makeshift stethoscope may also pinpoint the noise. If you still can't find the cause of the noise then you would have to start looking inside the engine.
Click to expand...
Actually I'll try to remove auxiliary belt as it just can't be the engine. All parts have been replaced, you name it. Heard it could be vacuum pump or fuel pump or even manifold flaps. But will definitely start with auxiliary belt
 
I know it's a pain in the neck trying to find these noises. The HPFP cam follower can make ticking noises when worn, worth changing that. It's a cheap part and easy to change.
 
Update on rattle battle:
After several checks and many different services, none could locate the source of rattle, everyone guessed either hydraulic lifters or cam chain and tensioner. Both brand new. Really frustrating. Funny thing is that on 5w40 rattles more often than 5w30. Could oil pickup pipe impact this? Since it's only thing not checked. I'll upload video of rattle tomorrow.
 
Did you not replace the pickup pipe when you rebuilt the engine? This known to block oil flow and cause a ticking noise at low revs / oil pressure?
 
nluk100 said:
Did you not replace the pickup pipe when you rebuilt the engine? This known to block oil flow and cause a ticking noise at low revs / oil pressure?
Click to expand...
Exactly at low rpms. Oil pressure was checked. Within limits. Could be cold oil doesn't get through pipe as fast as it should?
 
Aidris said:
Exactly at low rpms. Oil pressure was checked. Within limits. Could be cold oil doesn't get through pipe as fast as it should?
Click to expand...
Was the pickup pipe replaced? If not I would replace it as it is a know issue.
 
Cold engine nock noise metal to metal is when top engine /lifters not getting enough lubricant. Switch off the engine after starting in cold start state and restart again and you will notice most of the knocking disappear.
 
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xaudi said:
Cold engine nock noise metal to metal is when top engine /lifters not getting enough lubricant. Switch off the engine after starting in cold start state and restart again and you will notice most of the knocking disappear.
Click to expand...

Tapping noise from top of engine sometimes can miss one of the taps in sequence and continue.

Any mechanic should be able to diagnose lifters almost immediately ?
It’s like a ticking like injectors sound but much louder - like an old ford escort lol


Sent from my iPhone using Tapatalk
 
Yes a good mechanic would. Audi dealer should also if you leave the car overnight. The oil pump are all mechanical meaning only can pump the oil when engine starts.
Unfortunately changing the oil to no use also.
 
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Update one the car. So we've changed the pickup pipe, and put 10w40 oil. The sound is a lot more quiet but still persists. Hydraulic lifters are new. Could the oil pump balance shaft be the problem? Or shall we rebuild the engine again and see if we've missed something?
Here's a link to video https://youtube.com/shorts/ROt5GpRQkAI?feature=share
 
Just get some opinion from audi dealer first. Does this only on cold engine?
 
Although I’m not there and it is just from a video so don’t quote me on this but…

That is not lifters

that is bottom end noise.
it maybe piston slap but sounds to me like it’s more bearing noise.
pistons would fit more though with the “only when cold” and the rattle knock rather than a single knock per revolution-as you had apart and no bearing metal/oil paste in sump etc

I recon maybe piston/ring/bore areas to look at
What we used to call the death rattle on the green laners once we had hit and cracked a sump and still carried on driving for a while with no oil in engine. - but the noise obviously got louder and louder until the engine would seize over about 3mins.
it was a long time ago but recognise that sound from then you see
 
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The question is this happens only on cold start when car stand overnight. Engine oil not reaching on that part in question. Once the oil pump start pumping the noise disappears.

Keep looking into it good luck
 
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xaudi said:
The question is this happens only on cold start when car stand overnight. Engine oil not reaching on that part in question. Once the oil pump start pumping the noise disappears.

Keep looking into it good luck
Click to expand...

Or heats up and expands maybe?

Like the exhaust of a 1.2L car even, the manifold is too hot to touch about 5-10seconds after starting, so piston ring expansion etc as the bores will be hot as after a few seconds.
As I say it’s just a guess as I don’t have car in front of me, it’s just from a video so really hard to diagnose properly isn’t it


Sent from my iPhone using Tapatalk
 
Davill9 said:
Although I’m not there and it is just from a video so don’t quote me on this but…

That is not lifters

that is bottom end noise.
it maybe piston slap but sounds to me like it’s more bearing noise.
pistons would fit more though with the “only when cold” and the rattle knock rather than a single knock per revolution-as you had apart and no bearing metal/oil paste in sump etc

I recon maybe piston/ring/bore areas to look at
What we used to call the death rattle on the green laners once we had hit and cracked a sump and still carried on driving for a while with no oil in engine. - but the noise obviously got louder and louder until the engine would seize over about 3mins.
it was a long time ago but recognise that sound from then you see
Click to expand...
Hmmm that's the last place we'll look into cause we've changed the pistons, rings and everything. But who knows could be something done wrong.
 
It's quite interesting phenomena. Let's take an example. After night when engine revs itself to 1.2k to heat up there is no sound at all. Once it drops to normal idle (30 sec) it rattles, matching revolutions. And can't figure out why it doesn't rattle at start but does afterwards
 
Aidris said:
Hmmm that's the last place we'll look into cause we've changed the pistons, rings and everything. But who knows could be something done wrong.
Click to expand...

Who did the original work, Ie/ the rebuild

Yourself or a garage?
If it was yourself who did the re honing/ rebore on block for new pistons and to what size, and what is piston /ring size- standard or oversize ?

Oil should be reaching the head within a second or less on the tfsi engines, I have seen them started up without a rocker cover on, and if pump is working correctly, the head will be lubricated in seconds but bottom end should be the same too.


It is very frustrating I’m sure after you do all that work…
Hope you get a resolve soon mate that doesn’t cost you too much, and when you do, keep us all posted cos it helps other members in the future -it is an interesting one.

Edit; I listened again and if definitely not lifters or cam follower, I’d put money on bottom end somewhere.
Sent from my iPhone using Tapatalk
 
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Aidris said:
Good day gentlemen,
Either I'm being rickrolled by mechanics or I'm really unlucky. The deal is that I've rebuilt my s3 8p 2009. Cost over 4k €. New pistons, chains, tensioners. Literally everything new from engine block. Car drives smooth as butter. But the ding dong is that car still rattles when cold. To specify, after cold start settles down. Metal to metal. Dissapears when warm. Does anyone have any clue what could it be? Because soon I will identify as kilometers per second if the problem persists.. HELP!

EDIT: about the sound: rattle matches the revs. From idle to about 1.4k revs, then dissapears as you rev higher. Clutch in clutch out no difference. As car warms up the rattle becomes irrational, it knocks it does not then again until goes silent..
Click to expand...
 
Q1.
When you rebuilt the engine, did you do it yourself or was it done for you?
Q2.
Was the engine rebored or was it just re-rung?

What you are describing sounds like "Piston Slap" this occurs when the piston is cold and the clearance is excessive between the piston skirt and the cylinder wall.
As the engine warms up, the piston being made of alloy warms faster than the bore, thus, the noise or rattle diminishes.
Unfortunately, the only way to test this is to insert a feeler gauge between the piston and cylinder wall.

This tolerance should have been checked during the rebuilding of the engine.

In my experience mistakes do happen when engine's have been rebored and the wrong pistons have been issued to suit the engine.
I should point out, that without listening to the noise. The above diagnosis would be the worst cause.
 
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China Dave said:
Q1.
When you rebuilt the engine, did you do it yourself or was it done for you?
Q2.
Was the engine rebored or was it just re-rung?

What you are describing sounds like "Piston Slap" this occurs when the piston is cold and the clearance is excessive between the piston skirt and the cylinder wall.
As the engine warms up, the piston being made of alloy warms faster than the bore, thus, the noise or rattle diminishes.
Unfortunately, the only way to test this is to insert a feeler gauge between the piston and cylinder wall.

This tolerance should have been checked during the rebuilding of the engine.

In my experience mistakes do happen when engine's have been rebored and the wrong pistons have been issued to suit the engine.
I should point out, that without listening to the noise. The above diagnosis would be the worst cause.
Click to expand...
Brilliantly put mate. Wouldn’t add to it.
Im **** at the explaining and writing bit !
 
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