Help Diagnosing Idle Noise

[XxSullyxX123]

Hey guys,

For starters, I am NOT talking about the normal valve ticking or the cold start timing chain chatter. I have a new to me 2016 S4 DSG that I bought around two months ago. I dont recall my 2015 S4 6MT ever sounding like this.

The idling noise only occurs after the engine has been hot a bit (like after my commute home) and not on cold starts and I dont even think when its warming up a bit. It sounds like a dragging or groaning / rubbing noise coming from the back or possibly top of engine. Doesn’t sound like the belts. Sounds more like it could be the timing chain rotating on the guides, what a worn flywheel would sound like, bearings somewhere, or something of that nature. I am under factory warranty (also have CPO) and have audicare fyi.

Not that I can figure out what this would have to do with it, but i did only notice the noise after i did an in between oil change at 30k miles (using ECS OEM kit with castrol/oem filter and we extracted the oil). It’s most noticeable parked in between cars or a garage (due to echo factor). Not sure if you can hear it over the normal valve tick in the video, but in person it is quite noticeable. With the volume up on my iPad, I can hear it Over the ticking though.

Of course I can simply take it to the dealer (and may have to), but we all know how that goes when there is no CEL for their computers to check, and knowing the cars drives and performs perfectly. They’ll either find nothing, or start pulling things apart unnecessarily trying to track it down. Neither of which is helpful to me. It may be nothing to worry about, but it just seems out of place and I want to make sure I get it addressed before its a problem, if it is.

Thanks for looking


https://m.youtube.com/watch?v=ULRWzx7Rm3I
https://m.youtube.com/watch?v=vsF4vFyOpXE

[Audi_Andrew19]

Hey guys,

For starters, I am NOT talking about the normal valve ticking or the cold start timing chain chatter. I have a new to me 2016 S4 DSG that I bought around two months ago. I dont recall my 2015 S4 6MT ever sounding like this.

The idling noise only occurs after the engine has been hot a bit (like after my commute home) and not on cold starts and I dont even think when its warming up a bit. It sounds like a dragging or groaning / rubbing noise coming from the back or possibly top of engine. Doesn’t sound like the belts. Sounds more like it could be the timing chain rotating on the guides, what a worn flywheel would sound like, bearings somewhere, or something of that nature. I am under factory warranty (also have CPO) and have audicare fyi.

Not that I can figure out what this would have to do with it, but i did only notice the noise after i did an in between oil change at 30k miles (using ECS OEM kit with castrol/oem filter and we extracted the oil). It’s most noticeable parked in between cars or a garage (due to echo factor). Not sure if you can hear it over the normal valve tick in the video, but in person it is quite noticeable. With the volume up on my iPad, I can hear it Over the ticking though.

Of course I can simply take it to the dealer (and may have to), but we all know how that goes when there is no CEL for their computers to check, and knowing the cars drives and performs perfectly. They’ll either find nothing, or start pulling things apart unnecessarily trying to track it down. Neither of which is helpful to me. It may be nothing to worry about, but it just seems out of place and I want to make sure I get it addressed before its a problem, if it is.

Thanks for looking


https://m.youtube.com/watch?v=ULRWzx7Rm3I
https://m.youtube.com/watch?v=vsF4vFyOpXE

I had the same questions not that long ago. I’ve basically concluded that DI engines make a lot of clicking and clanking and that most of it is normal (unless it’s really loud or off-sounding). I actually took a video for when I posted in here as well, let me know if the sounds you’re referring to are the same you hear on mine.

https://youtu.be/KJqSR5VSFfo

[XxSullyxX123]

I had the same questions not that long ago. I’ve basically concluded that DI engines make a lot of clicking and clanking and that most of it is normal (unless it’s really loud or off-sounding). I actually took a video for when I posted in here as well, let me know if the sounds you’re referring to are the same you hear on mine.

https://youtu.be/KJqSR5VSFfo

Yes, its clearer (and even louder ) in your video. I think the sound is the same, but not sure. It doesn’t bother me per se, it just struck me the first time i noticed it and now i listen for it. The only part that bother me is that in 2 1/2 years of owning my last one i never noticed it and i am SURE I would have if it did it. I’m too perceptive to little things.

EDIT: Did you ever get it addressed at the dealer?

[C6Avant]

Both sound normal to me.

[seandon_792]

Mine sounds just like Andrews video. No codes, no cel, no overheating or decrease in gas mileage and it’s been a few thousand miles since I noticed it.

Strange but I even had it looked at by a decent Indy shop and they couldn’t dig anything up without a full tear down.


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[XxSullyxX123]

Mine sounds just like Andrews video. No codes, no cel, no overheating or decrease in gas mileage and it’s been a few thousand miles since I noticed it.

Strange but I even had it looked at by a decent Indy shop and they couldn’t dig anything up without a full tear down.


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Interesting. do you hear it when the engine is cold, or only after it is hot like mine? My oil level prior to my change (the way it was when I bought it from audi) was near the low end on the MMI and now it is near the top. I wouldn’t think more oil would make the noise come out, if anything less. I’d say maybe the oil viscosity makes certain noises louder for sure, but i used OEM 5w40.

[seandon_792]

It’s only at operating tempt, never heard it cold before. I’ve used 3 different types of oils all the same weight 5w40, never low on oil according to physical dipstick though. All giving the same sound regardless


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[Djcurb98]

Maybe look into the possibility of it being your needle bearings in your supercharger. They sit in the back of the super charger and there’s 2 of them (one for each rotor) it holds them up in the back and is an essential part to helping your supercharger, the noise would be from the top and the back of the supercharger house so double check that location!


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[XxSullyxX123]

Maybe look into the possibility of it being your needle bearings in your supercharger. They sit in the back of the super charger and there’s 2 of them (one for each rotor) it holds them up in the back and is an essential part to helping your supercharger, the noise would be from the top and the back of the supercharger house so double check that location!


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Interesting. Are these common fail parts? Not sure i’ve Read much of supercharger issues over the years on the newer b8.5’s. If it was a bearing, wouldn’t the sound be audible at any operating temp? I dont have any special auto stethoscopes at home, but the back of the engine is where it appears to be most audible. Whether atop at the supercharger, back by timing chain area, or lower near DSG, I cant tell.

[Djcurb98]

Interesting. Are these common fail parts? Not sure i’ve Read much of supercharger issues over the years on the newer b8.5’s. If it was a bearing, wouldn’t the sound be audible at any operating temp? I dont have any special auto stethoscopes at home, but the back of the engine is where it appears to be most audible. Whether atop at the supercharger, back by timing chain area, or lower near DSG, I cant tell.

Typically it sounds like a rock tumbler noise and it’s usually a hit or miss, some cars they fail some cars Last 150k no problem. Also yes you would hear it at any temp but I keep an open mind about things like that in the sense that maybe once it heats up a little the metal expands and starts to make noise?? Just thinking outside the box lol not saying that’s what the problem is

[XxSullyxX123]

Typically it sounds like a rock tumbler noise and it’s usually a hit or miss, some cars they fail some cars Last 150k no problem. Also yes you would hear it at any temp but I keep an open mind about things like that in the sense that maybe once it heats up a little the metal expands and starts to make noise?? Just thinking outside the box lol not saying that’s what the problem is

Got it. Makes sense. I’ll google around for videos on supercharged motors with that issue and compare. Absolutely, An open mind is what this forum is all about, and why I asked. Thanks

[Djcurb98]

Got it. Makes sense. I’ll google around for videos on supercharged motors with that issue and compare. Absolutely, An open mind is what this forum is all about, and why I asked. Thanks

No problem!

[Djcurb98]

Eaton TVS R1320 supercharger rebuild and slight porting
https://www.audizine.com/forum/showthread.php?t=852520
Good thread if you want to explore this way as a possibility


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[Obeynation]

Mine sounds similar if anything i feel like my supercharger noise is louder maybe the bearing is going out . https://youtu.be/Ccwzl506bk0


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[XxSullyxX123]

Eaton TVS R1320 supercharger rebuild and slight porting
https://www.audizine.com/forum/showthread.php?t=852520
Good thread if you want to explore this way as a possibility


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Thanks. Hearing some videos it seems like the noise is much louder and more pronounced if it’s a bearing. Listening around on YouTube at random videos of b8/b8.5 engines (ie checking out intake videos and listening to idle before they rev) i feel like i hear the same noise on all of them that I do on mine. I just cant believe if what I’m hearing happens to be normal, I never noticed on my last s4.

[XxSullyxX123]

Mine sounds similar if anything i feel like my supercharger noise is louder maybe the bearing is going out . https://youtu.be/Ccwzl506bk0


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Yea something definitely seems to be going on there. More pronounced near front end and higher pitched. Supercharger belt perhaps?

[Obeynation]

Yea something definitely seems to be going on there. More pronounced near front end and higher pitched. Supercharger belt perhaps?

No idea just got this car and was doing a b8.5 rebuild in the front , new supercharger belt on it . Might have to create new thread don’t want to thread jack.


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[C6Avant]

Open your oil filler cap while at idle and see if the noise you're hearing gets louder.

[XxSullyxX123]

Open your oil filler cap while at idle and see if the noise you're hearing gets louder.

Interesting idea. I guess would isolate internal engine noise vs anything else like supercharger

Edit: I thought you weren’t ever supposed to take the cap off while running. Myth?

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[C6Avant]

Interesting idea. I guess would isolate internal engine noise vs anything else like supercharger

Edit: I thought you weren’t ever supposed to take the cap off while running. Myth?

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It won't hurt anything.

[XxSullyxX123]

Ok I'll try that later, just to see if it narrows anything down.

[XxSullyxX123]

Ok, did not take the oil cap off. Turned it and went to pull and there is an enormous vacuum so I don’t want to mess anything up and have the motor sucking in unfiltered air through the oil cap.


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[Emporio]

I've noticed the same sound you are talking about on my S5. It's almost like a gurgle/bearing grinding/rock tumbler sound. Do you notice a reduction in sound when you put the car in drive or neutral? For me, the sound basically disappears when I put it in gear. I mostly notice the sound when inside a garage with walls close, but it seems to get slightly better when warm. It's really hard to locate and I almost think it might be my belt tensioner pulley. Sound has been there since I purchased and no codes have shown up in the 20,000km since I've owned it. Never got worse or better. I searched endlessly online for what it could be but never found anything. Not sure if the sound is normal or what.

[XxSullyxX123]

I've noticed the same sound you are talking about on my S5. It's almost like a gurgle/bearing grinding/rock tumbler sound. Do you notice a reduction in sound when you put the car in drive or neutral? For me, the sound basically disappears when I put it in gear. I mostly notice the sound when inside a garage with walls close, but it seems to get slightly better when warm. It's really hard to locate and I almost think it might be my belt tensioner pulley. Sound has been there since I purchased and no codes have shown up in the 20,000km since I've owned it. Never got worse or better. I searched endlessly online for what it could be but never found anything. Not sure if the sound is normal or what.

I actually was noticing this EXACT thing last night. Seems to be loudest in Park, and much quieter in D or N. I wouldn’t say silent but definitely not noticeable unless I really listen for it in D or N. So now I’m thinking its likely normal. My biggest concern was I dont remember hearing it on my last S4, but now hearing a sound difference based on the gear, I’m thinking I never noticed it because it was 6MT, and maybe its some sort of specific extra normal sound that emits from the engine or DSG due to the DSG. My 35,000miles service is coming up in a few months and they’ll do a DSG fluid change. Maybe the noise will go away or maybe not. Who knows.....

[C6Avant]

Ok, did not take the oil cap off. Turned it and went to pull and there is an enormous vacuum so I don’t want to mess anything up and have the motor sucking in unfiltered air through the oil cap.


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Excessive vacuum is not normal. There should be some suction, but not an enormous amount to where you really need to pull to get the cap off. Briefly letting unmetered air into the crankcase isnt going to hurt anything. If suction is very high your PCV system may be failing.

Someone please correct me if I'm wrong.

[XxSullyxX123]

Excessive vacuum is not normal. There should be some suction, but not an enormous amount to where you really need to pull to get the cap off. Briefly letting unmetered air into the crankcase isnt going to hurt anything. If suction is very high your PCV system may be failing.

Someone please correct me if I'm wrong.

Really? For a naturally aspirated motor perhaps, but with a supercharger there should be pretty good vacuum at idle no? Considering the rotors are spinning even at idle given they are belt driven. In any event, I didn’t try to yank the cap off. Physically I couldve easily gotten it off, I just felt a vacuum and then left it alone. It felt strong, but I’ve never tried to take a cap off on any vehicle while running, so I have nothing to compare it to.

EDIT: just googling quick, the lack of vacuum would indicate possible PCV issues. The presence of vacuum seems to be the PCV doing its job.

[Emporio]

Really? For a naturally aspirated motor perhaps, but with a supercharger there should be pretty good vacuum at idle no? Considering the rotors are spinning even at idle given they are belt driven. In any event, I didn’t try to yank the cap off. Physically I couldve easily gotten it off, I just felt a vacuum and then left it alone. It felt strong, but I’ve never tried to take a cap off on any vehicle while running, so I have nothing to compare it to.

EDIT: just googling quick, the lack of vacuum would indicate possible PCV issues. The presence of vacuum seems to be the PCV doing its job.

When I pull my oil cap on there is strong vacuum, which is normal. My idle speed increases, it's basically creating a huge vacuum leak and letting a bunch of unmetered air in. I have very minimal oil loss over 5000km, around half a quart. I'd say it's alright.

[Emporio]

Really? For a naturally aspirated motor perhaps, but with a supercharger there should be pretty good vacuum at idle no? Considering the rotors are spinning even at idle given they are belt driven. In any event, I didn’t try to yank the cap off. Physically I couldve easily gotten it off, I just felt a vacuum and then left it alone. It felt strong, but I’ve never tried to take a cap off on any vehicle while running, so I have nothing to compare it to.

EDIT: just googling quick, the lack of vacuum would indicate possible PCV issues. The presence of vacuum seems to be the PCV doing its job.

When I pull my oil cap on there is strong vacuum, which is normal. My idle speed increases, it's basically creating a huge vacuum leak and letting a bunch of unmetered air in. I have very minimal oil loss over 5000km, around half a quart. I'd say it's alright.

Also, I'm 100% sure the sound is not coming from the DSG. I've gotten under there and it's not making any noise. I did my DSG flush 10000km ago and it made no difference. My DSG is smooth as butter always.

[XxSullyxX123]

My DSG is smooth as butter too. Likely has nothing to do with it, just interesting that the noise louder in park. But perhaps once it’s in gear, even if not moving, the engine has load on it and it quiets out whatever the noise is.


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[Audi_here]

This is the dual mass flywheel noise. You can try having the dealer loosen the fly wheel bolts and retighten them, if the noise does not go away you need a new dmf. Have dealt with this many times.

[Emporio]

The noise sounds somewhat similar to DMF but it's not the same. The sound doesn't originate from from the lower part of the engine, it's near the top and front. I've gotten underneath and it's not coming from the trans, at least in my case, it's not DMF.

[Audi_here]

Pull the belly pan off and remove the fly inspection plate and let it idle and listen to it. Also see if the flywheel is wobbling. When the dmf makes this noise it's confusing because you can hear it from the top back of the engine. Sometimes when it's not bad you'll only hear it from the top.

[Waffles_s4]

Hmm noise of the OP sounds normal to me. The noise from the user Obeynation however does not sound normal to me.

[XxSullyxX123]

Thx gents. Feels normal just sounds imperfect.


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[s4matty]

My 2015 i just bought has the same sound
And a 2014 i worked on last week.
When i pull the hose off going to intake pipe that comes from pcv theres alot of suction and it comes and goes.
im wondering if its pcv related?
Going to pull the cap off the pcv when i port my charger next week to see if the diaphragm is torn or something

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[92cpe]

Mine makes the same noise for as long as ive had it. Audi says its normal of course. I suspect its either sc bearing or pcv valve. When i install a ported and rebuild sc ill change the pcv at that time. Im hoping one of the two fix the noise.

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[Ricketch]

My mechanic told me that this sound was just loud fuel injectors. He also has a B8 S4

[XxSullyxX123]

My mechanic told me that this sound was just loud fuel injectors. He also has a B8 S4

Yes, dealer told me last year when I inquired during a service visit it’s completely normal. I just never updated this thread, sorry! Car run beautifully.

[Acuransx1]

I have exact same issue as the OP in my A6 3.0T (2015). I'm interested in hearing from anyone here who has had this issue somewhat long term and whether they have had to replace the S/C.

My car has 46K miles and warranty expired. I don't care much for the noise (exactly like link at very bottom of post #2) but am willing to live with it unless it is likely that I will have to replace the S/C in next 20-25K miles. I am not going to keep the car long term.

Any help/input gratefully received. Thanks.

Best,
Jeff

[Acuransx1]

To follow up on my post above, I sent PMs to a number of AZ members who have mentioned their cars have this subtle knocking noise at idle when not in gear. Everyone who responded to me (you know who you are, thanks) has not experienced any issues other than the subtle noise. That is good news. My indy and dealer had no idea what this noise is and dealer wrote up a RO in case something lets you in the future so we have something to discuss with Audi corporate and to evidence that this came on quite early in the car's life.

I had a Blackstone oil analysis done to (hopefully) rule out any abnormal internal engine wear issues that have started -- came back totally fine -- no abnormal metal concentrations or anything else for that matter.

So, I will just put this subtle noise out of my head and enjoy my A6 3.0T for the next 20-25K miles (intend to keep it up to about 70K miles and then move on to something else).

Best,
Jeff