1.4 BHC - Stubborn engine related noise ...

Bordos

Bordos

Member
Poland
Hello,

At the beginning - I looked trough almost all threads related to TDI rattle/noise etc. and when applicable I did things other used do - without any effect...

My 2005 1.4 TDI BHC Audi A2 is very stubborn with a rattle like noise coming from the engine bay - although I am trying to trace its source I was not able to do so.

This noise occurs between 1500-1900 rpm, it sound does not seem to be related with engine speed (it just occurs and then above 1900 rpm or below 1500 its gone). Its not always present, but it seem to be more frequent when it is cold. Its present regardless of clutch status (on/off). It is like this for about 2 years now.
What is important: the car is running normally, no "Check engine", no fault codes, it has its power, etc. Everything is perfectly fine aside from that noise...

What did I do trying solve it:
1. Replaced timing belt set (with all rollers etc.) - no effect,
2. Replaced oil pump chain set (including the tensioner, sprockets, new bolts etc.) - no effect,
3. Replaced auxiliary belt with its tensioner - no effect,
4. Replaced alternator pulley - no effect,
5. Replaced "dog bone" (bottom engine bracket) - no effect,
6. Checked all noise covers around the exhaust for a loose one - all are solid,
7. Checked engine lifting eyes (saw a thread here that those can get loose) - all are solid,
8. Got under the car with a friend reving the engine so that the noise is present - it is very hard to distinguish it from below the car (this engine is not very "silent") but it seem that it can be heard from between the engine back and cars body).
9. Looked around the fuel line with the noise silencers (also found a thread here that similar noises can came from fuel lines) - this does not look bad in any way.
10. Looked at two remaining engine mounts - both look stiff.

Does any of you have any other ideas where to look for the source of this noise ? I really need to trace it as I am loosing my confidence about this car...
 
There is a fixing on the bulkhead that has been known to cause a rattling / vibrating kind of noise.

I don't know too much about it but apparently it's just a nut that works itself loose but is not obvious and a little difficult to see and get to but as you seem to have checked or replaced most of the other potential culprits it might be something to look into a little more 👍
 
A2Z said:
There is a fixing on the bulkhead that has been known to cause a rattling / vibrating kind of noise.

I don't know too much about it but apparently it's just a nut that works itself loose but is not obvious and a little difficult to see and get to but as you seem to have checked or replaced most of the other potential culprits it might be something to look into a little more 👍
Click to expand...
Do you have more information about this? Thread link or some picture where to look for it ?
 
Bordos said:
Do you have more information about this? Thread link or some picture where to look for it ?
Click to expand...
these ones? I searched for "Scuttle Rattle Audi A2" on google and these were among the threads linked. I knew I remembered reading them years ago, but drew a blank finding these links earlier.

Metal hitting sound coming from inside the dash

I have discovered my long issue with a metal hitting sound coming from inside the dash. I think It's a common issue and it have a very annoying sound, especially on the A2 fitted with diesel engines. It is the metal bar linking the top bracket behind the instruments towards the windscreen. This...
www.a2oc.net www.a2oc.net

Rev Specific Rattle

Hi, I'm suffering with a really annoying rattle that seems to be rev dependant; between 1200 - 1400 RPM. I fairly sure it's outside the cabin, possible in the engine bay. So far, I've checked that the under tray is secure, the bonnet corners are tight, the MAF sensor is not hitting the...
www.a2oc.net www.a2oc.net
 
I have same 1.4 bhc engine with exactly the same rattle as you. It's a 90k car and got the rattle about 2 years ago and it's running like a dream when warmed up rattle is not present as much as when cold but it's still there occasionally. Same as you
I replaced everything except one thing which I hope is the issue. I'm glad you didn't mention on your list anything related to the clutch which I think could be the culprit either the plate bolts rivets spring bearing who knows I'll drop the gearbox soon and will find out.

Another thing is I can't hear the rattle when windows are open only when radio is off all windows shut and then it comes and goes. Almost imposible to locate when you are in the engine bay and reving it.

It's |really bad during winter cold morning and almost non existent during summer.
 
Another idea just popped into my head and might be a red herring as the rattling bolt I suggested earlier could also be.

I'm just wondering whether it could be something as simple as a vibration from the engine cover that is fixed on with the 3 nuts?

I bet most of the cars no longer have the foam that was underneath it and that cushioned between the cover and the engine and I wondered whether the car or cars in question might have recently had it removed or whether it has disintegrated as many have?

It would be a nice easy, cheap fix and easily ruled out by removing the 3 nuts and engine cover and going for a drive! 🤞😁
 
bix said:
I have same 1.4 bhc engine with exactly the same rattle as you. It's a 90k car and got the rattle about 2 years ago and it's running like a dream when warmed up rattle is not present as much as when cold but it's still there occasionally. Same as you
I replaced everything except one thing which I hope is the issue. I'm glad you didn't mention on your list anything related to the clutch which I think could be the culprit either the plate bolts rivets spring bearing who knows I'll drop the gearbox soon and will find out.

Another thing is I can't hear the rattle when windows are open only when radio is off all windows shut and then it comes and goes. Almost imposible to locate when you are in the engine bay and reving it.

It's |really bad during winter cold morning and almost non existent during summer.
Click to expand...
Your description match my issue 1:1 …

With opened windows I cannot hear this rattle …

I was thinking about clutch but regardless of its position the rattle can be heard - therefore I did not consider it.

Are you planning to replace it any time soon ?
 
A2Z said:
Another idea just popped into my head and might be a red herring as the rattling bolt I suggested earlier could also be.

I'm just wondering whether it could be something as simple as a vibration from the engine cover that is fixed on with the 3 nuts?

I bet most of the cars no longer have the foam that was underneath it and that cushioned between the cover and the engine and I wondered whether the car or cars in question might have recently had it removed or whether it has disintegrated as many have?

It would be a nice easy, cheap fix and easily ruled out by removing the 3 nuts and engine cover and going for a drive! 🤞😁
Click to expand...
I wish it was as easy but I don't have the cover at all and the noise is still there it's definitely coming from inside the engine block.
 
My second A2 which is also 1.4 BHC almost on 170k just started to develop the same rattle. The very distinctive rattle last for a fraction of the time of my other car but it just started doing it as well. I'm excepting it to be longer and louder as months go by hopefully we will manage to find out the root. I'm betting it's either clutch or gearbox related issue.
 
Bordos said:
Your description match my issue 1:1 …

With opened windows I cannot hear this rattle …

I was thinking about clutch but regardless of its position the rattle can be heard - therefore I did not consider it.

Are you planning to replace it any time soon ?
Click to expand...
Yes my symptoms are exactly indetical to yours I'm pretty sure it's the same issue. I just bought new clutch last week. I still need few more bits and hopefully some nice weather for a change to replace it. I have big hopes for getting rid of the rattle by replacing everything single nut and bolt withing the clutch assembly. By the way if you search the forum there is quite few people with 1.4 BHC related rattle so it's pretty common. Plus on top of that if you have radio on all the time or windows down you might never noticed the noise. I'm mechanically minded person and I know this distinctive rattle is definitely not good.
 
bix said:
Yes my symptoms are exactly indetical to yours I'm pretty sure it's the same issue. I just bought new clutch last week. I still need few more bits and hopefully some nice weather for a change to replace it. I have big hopes for getting rid of the rattle by replacing everything single nut and bolt withing the clutch assembly. By the way if you search the forum there is quite few people with 1.4 BHC related rattle so it's pretty common. Plus on top of that if you have radio on all the time or windows down you might never noticed the noise. I'm mechanically minded person and I know this distinctive rattle is definitely not good.
Click to expand...
I will be waiting for your feedback of the clutch change result - If it will solve the issue I will do mine as well.
 
bix said:
Yes my symptoms are exactly indetical to yours I'm pretty sure it's the same issue. I just bought new clutch last week. I still need few more bits and hopefully some nice weather for a change to replace it. I have big hopes for getting rid of the rattle by replacing everything single nut and bolt withing the clutch assembly. By the way if you search the forum there is quite few people with 1.4 BHC related rattle so it's pretty common. Plus on top of that if you have radio on all the time or windows down you might never noticed the noise. I'm mechanically minded person and I know this distinctive rattle is definitely not good.
Click to expand...
Any updates :) ? How is your clutch replacement going ?
 
Didn't swap the clutch yet due bad weather ill wait till the summer we didn't have single weekend without rain since last October it's a solid 2 day job and I don't want to lie down in mud
 
bix said:
Didn't swap the clutch yet due bad weather ill wait till the summer we didn't have single weekend without rain since last October it's a solid 2 day job and I don't want to lie down in mud
Click to expand...
Make sure you fit a quality clutch kit the cheap ones are known to rattle!
 
It would help if the OP could upload an audio file (is that possible @ben ?) I have a BHC and always put the sound down to being a diesel (it's my first diesel). I only get it when cold. When air temperatures reach 15C and the engine is warm then the noise goes away and it just purrs along.
 
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