Milltek exhaust valve issue

[Dasquade]

So i had this issue on my left tailpipe a year ago, meanly that the valve would not open.
I had grinded the lip a bit and in the end i got it sorted, no issues and normal behaving valve.
Untill i few weeks ago inspected my right valve...I'll be damned, now it is the right one that is blocked!!
I tried to contact Milltek, sended them video and explained what the malfunction is.....no help from them since then :(.

Anyway, so Milltek has this 'lock' feature, witch is basicly a spring that is pushing the valve upwards into a very thinny grove in the tailpipe.
Once you install your OEM actuator with the stock turning spring, that spring should counter force the milltek spring and freely open/close the valve.
.....In theory, but in reality the stock spring is not strong enough or wears out over time so the milltek spring is too strong and thus keep the valve locked (without you knowing it...and maybe risk unbalanced pressure in exhaust system. Afaik the ECU has a engine protection mode to always open the valve under heavy load...unless Milltek designs a valve that fails!!).

Anyways, since Milltek doesn't man up, looks i'll have to do it myself.
Does anybody know if that milltek spring would be located underneat the valve rod? There is this extra piece, i suspect it is a hallow tube containing a spring. About to grind the bastard off....

For your information, i had recently put my stock exahust on and OEM valves don't have this extra piece under the valve NOR does it need force to push the valve downards before opening. Not sure why Milltek added this in the first place (maybe for anti-rattling valve noise).

Added small movie of the blocked valve and the downwards pushing to open it. With my hand it works, but the stock spring isn't strong enough (sadely new spring isn't sold seperatly).
*nevermind the movie, it was too big and couldn't upload :(.

[snohman]

I had read from a few others issues with the Active Valve control system locking up, but were older posts and no resolution. Was curious to see if you had this installed as well with your valvesonic exhaust system?

[Dasquade]

I do have the cete exhaust valve module, but almost 100% sure it is unrelated...
*the actuators on both side to their 'recalibration' test every time you turn on the ignition (witch is actually a dual open/close cyclus)
With the milltek installed i still kinda had my doughts, but since the stock exhaust is back on the car for my yearly car inspection and they working flawless, it is plain obvious for me it is the (failed) design feature of the milltek valves.
Since i'm not getting an answer of Milltek, looks i will have to try figuer it out myself.
Since i had an exhaust leak (unrelated to the milltek etc) i noticed first hand how delicate this can be to the performance and guess in long term not good aswell, i suppose a blocked exhaust (okey still got the muffled exhaust exit) but can't be good.

Anyway, still got some time before the milltek goes back under the car, but will try to cutoff or at least try to look into that piece in the near future (that spring has to go).

For what it is worth, other milltek users might want to look at their valves aswell....something tells me it isn't a isolated issue.

[Dasquade]

20180317_113319.jpg
For what it is worth, so today i grinded off the top of those 'mistary' metal pipes under the milltek valves.
As expected it is a hallow pipe holding a spring that pushes the valve upwards (locked).
Removed the spring, baby smooth opening valves again.
In a month i will mount the milltek back to the car and know more, but expecting them to work flowless from now on!!
*again i would like to remind other milltek owners to check their valves if they still perform as wanted ;). If not, this might be an easy fix! (milltek didn't replied back)

Will be removing the H and replace with smoother X pipe aswell soon.

[snohman]

Nice job on getting that sorted out on your end - will be curious to see how it works out going forward for you. Has made me little hesitant to pick up the valvesonic Milltek now.

[Dasquade]

Well to be honest, i started to loose faith in Milltek as a quality brand.
I understand the valves come under a lot of force and heat/carbon condition, but it they decide to add a 'lock' feature with counter spring they should at least make sure it is bulletproof. My exhaust is 1.5 years old (or is it 2.5years) old, but only doing +-10.000km a year.
Ohwell, at least glad i found out my valves got stuck (first left, then year later the right). I'm almost sure the unbalance, dispite the little H and in the end gases can still escape through the mufflers itself, it just can't be good running with one valve closed and other open etc....UNDER LOAD. So please let this (again) be a warning to others. I can't believe i'm an isolated case....

[sszyma]

I just had this same issue! Pulled the actuator off and it moved freely what up to the point of closing. It almost seemed like it was magnetically latching right at the end when moving by hand. Seeing how that springworks this makes sense!

[Dasquade]

I just had this same issue! Pulled the actuator off and it moved freely what up to the point of closing. It almost seemed like it was magnetically latching right at the end when moving by hand. Seeing how that springworks this makes sense!

Yup...it is that little spring locking the valve. I suggest you simply drill it open and remove the spring on both. Working flowless without flapper noises since i did it

[sszyma]

Did you cut the bottom off just a little or did you drill out the center?

[Dasquade]

Did you cut the bottom off just a little or did you drill out the center?

I did indeed cutted of the bottom (that lip if i recall) but as you can see in the picture you can actually drill dead center :).
Good luck, with some luck you don't even need to put the car on the bridge...

[sszyma]

Three minutes with Dremel on second convolution and pop it just freed up! What a simple fix!

[wittmer25]

So I have an RS3 with the Milltek valved exhaust, and I believe I have the same problem as both of you. The exhaust has only been on the car for about a year, and I can't get the valves to work. The exhaust sound never changes between dynamic and comfort. Are your valves still working after removing the spring? Any problems since the modification?

[Dasquade]

So I have an RS3 with the Milltek valved exhaust, and I believe I have the same problem as both of you. The exhaust has only been on the car for about a year, and I can't get the valves to work. The exhaust sound never changes between dynamic and comfort. Are your valves still working after removing the spring? Any problems since the modification?

Not at all, never worked better then right out the box. Still working flowless now :).

[PeoplesChoice]

Hey guys, I installed the Resonated Cat Back Milltek exhaust today and 2 things don’t seem right.
1.) It seems quieter than the stock RS7 exhaust
2.) It sounds the same in normal Drive mode as it does in Dynamic Sport mode
How can I check if the valves are working?
Can I replace the Resonated mid section for an X or H Pipe? Pros or cons?

[Dasquade]

Hey guys, I installed the Resonated Cat Back Milltek exhaust today and 2 things don’t seem right.
1.) It seems quieter than the stock RS7 exhaust
2.) It sounds the same in normal Drive mode as it does in Dynamic Sport mode
How can I check if the valves are working?
Can I replace the Resonated mid section for an X or H Pipe? Pros or cons?

Seams odd....
If not mistaken by default/stock...after startup in dynamic the valves will close again after a few seconds.
But normally if you switch again between comfort and dynamic the valves should go open.
You can also toggle the valves if you change them in your individual drive select mode: motorsound.
You can always visually inspect inside the exhaust if you see them open or closed (unless rs7 2014 has the valves in different location more to the front?
S6 c7 2013 with cete module so different behavior here....

You could replace the mid section with H or X pipe (that is what makes the non resonate version). By default Milltek offers H pipe (actually a very thinny and even smaller inner diameter cross pipe i noticed when i removed mine). Going for smooth X pipe makes it much civile and softer (more of a blown turbo sound versus rubble in the jungle tractor with the H). Not sure if that did the job, but i was having powercuts under semi boost with the milltek H. Swapped to OEM "M" plugs, didn't fixed it, swapped to the NGK "race" plugs, didn't fixed the issue. This year i swapped to X pipe, didn't fixed it....recently switched back to the +-1.000-3.000km used oem "M" plugs i had tested year before.....PERFECT smooth semi boost building performance without stutter under same condition before the two 'fixes' (stage 2 for the record). Just saying, if you change things, it can effect other things ;).

[PeoplesChoice]

Thanks for the response, I appreciate it. I figured out the valves, they are working which is great. I went ahead and ordered the mid section H pipe from Milltek, so should be an easy swap. I’m going to save the Resonated section in case it’s too loud after I do the Stage 2 with APR downpipes. I figure the H pipe will get me by for a while before doing the Stage 2. Hopefully it all works out, but I’ll keep you posted! My only concern now is connecting the APR downpipes to the Milltek exhaust since they’re different diameters. Sounds like it can be done, but I hope the local APR dealer/installer can/will do it. Do you know of anyone that sells a pre-fabricated connector by chance?


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[Dasquade]

Going from resonate to non resonate will be a big change :) going for non resonate too apr dp's will be semi big change but in total LOAD :p. All i can said an X pipe on the milltek setup will make it much more refined and civil.
If the H to X pipe combined with oem "M" is the perfect combination to avoid low boost buildup stutter....time will tell but at least you know in case you encounter it when you go stage 2 (but i am catless).

As for the apr->milltek adaptor, not sure if it excist. But i know i made 3"->2.5" adaptor for my stock exhaust with sportscats (for emission inspection). An easy quick release V band makes swapping a breez (swapping exhausts in 1 houre with lift).
Tip: get your quick release bands in China...same build quality (wouldnt be suprised shop buying the same) at 1/3 of the price!

[PeoplesChoice]

Can you give me more info on the sportscast? The only reason I haven’t done the Stage 2 is because I have to pass emissions too and didn’t want to deal with. Sounds like you may have figured it out though.


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[Dasquade]

Not much special, just some unbranded sportcats i bought from a dutch exhaust fabricator. We don't have readyness test, just sniffer test.
I installed them in my stock exhaust and just swap exhaust when i have my yearly inspection. Car did 0.06% CO so good under the 0,20% they put limit on.
Other forum member had them on his car as well and drive with them always.

[DiamondZ]

Well to be honest, i started to loose faith in Milltek as a quality brand.
I understand the valves come under a lot of force and heat/carbon condition, but it they decide to add a 'lock' feature with counter spring they should at least make sure it is bulletproof. My exhaust is 1.5 years old (or is it 2.5years) old, but only doing +-10.000km a year.
Ohwell, at least glad i found out my valves got stuck (first left, then year later the right). I'm almost sure the unbalance, dispite the little H and in the end gases can still escape through the mufflers itself, it just can't be good running with one valve closed and other open etc....UNDER LOAD. So please let this (again) be a warning to others. I can't believe i'm an isolated case....

I'm dealing with it for a month now. First when I got it installed the flapper would rattle when open, now they are getting stuck. I regret getting them all together. Im going to dremel the ends off and pull the spring. Can I do it with the pipes on the car? DId you get any rattling?

[Dasquade]

I'm dealing with it for a month now. First when I got it installed the flapper would rattle when open, now they are getting stuck. I regret getting them all together. Im going to dremel the ends off and pull the spring. Can I do it with the pipes on the car? DId you get any rattling?

Yes possible with exhaust on car. The ends are facing downwards so perfectly in reach :). DO IT! Been working perfectly since then...
No rattling and the rattling actually comes more from the wastegates. They are designed as a twisting dual port flapper and my understanding is the milltek stock muffler resonates that sound extra! Since i removed their H pipe and placed X pipe the rattling is way less same for the 'tractor' sound. It does make the exhaust more quiet and less rough but personally very happy with the result as it sounds more refined then before :).

[1Jeffersonc]

20180317_113319.jpg
For what it is worth, so today i grinded off the top of those 'mistary' metal pipes under the milltek valves.
As expected it is a hallow pipe holding a spring that pushes the valve upwards (locked).
Removed the spring, baby smooth opening valves again.
In a month i will mount the milltek back to the car and know more, but expecting them to work flowless from now on!!
*again i would like to remind other milltek owners to check their valves if they still perform as wanted ;). If not, this might be an easy fix! (milltek didn't replied back)

Will be removing the H and replace with smoother X pipe aswell soon.

I just wanted to say THANK YOU!!!! this fixed my squeaking Milltek valves on my SQ5, it was driving me crazy and it was seriously loud, enough to be heard over the exhaust at idle. So again Thanks.

[Dasquade]

I just wanted to say THANK YOU!!!! this fixed my squeaking Milltek valves on my SQ5, it was driving me crazy and it was seriously loud, enough to be heard over the exhaust at idle. So again Thanks.

No problem, enjoy :).

[Krueger]

Been dealing with this issue the past three month. started to have issue during cold starts. I had the exact same valves on my S3 and never had an issue. I also regularly would wash both the S3 and S6 valves with Wd40 and that would get rid of the "squeak" as the system constantly checks the location pf the valves. I'm currently working with some others to give us non-'RS' owners the same kind of control they have over the values. Dynamic = open 100&, Comfort closed = 100&, Auto (I HIGHLY recommend not using this mode unless the car has been on a lift for days, also, don't set your individual characteristics to Auto, especially the sports differential, Air-suspension, engine/transmission, or dynamic steering.....lol I gues the exhaust wouldn't be that harmful. btw I ripped apart the inside of one of the exhaust valve motors, the engineering inside there is brilliant. I'll post pictures if anyone wants them.

[Dasquade]

Been dealing with this issue the past three month. started to have issue during cold starts. I had the exact same valves on my S3 and never had an issue. I also regularly would wash both the S3 and S6 valves with Wd40 and that would get rid of the "squeak" as the system constantly checks the location pf the valves. I'm currently working with some others to give us non-'RS' owners the same kind of control they have over the values. Dynamic = open 100&, Comfort closed = 100&, Auto (I HIGHLY recommend not using this mode unless the car has been on a lift for days, also, don't set your individual characteristics to Auto, especially the sports differential, Air-suspension, engine/transmission, or dynamic steering.....lol I gues the exhaust wouldn't be that harmful. btw I ripped apart the inside of one of the exhaust valve motors, the engineering inside there is brilliant. I'll post pictures if anyone wants them.

Yeah, the squeaky noises are bad BUT i think that is on most exhausts and not specificly milltek only. Was looking at an performance rs6 youtube movie the other day (akra) and had it too.
With the lower spring out it might be possible to squirt in some thermal paste. Will do it one of these days but my valves are always open (CETE module but every xx startups it automaticly recalibrates anyway).
Please share picture, always in for some insight...

[Omychron]

Sorry to revive an old thread, but was wondering if you ever had any further issues after cutting off the spring?

Looks like the Milltek exhaust on my S5 has the same issue, and I'd rather be sure before cutting it up!

[Dasquade]

Sorry to revive an old thread, but was wondering if you ever had any further issues after cutting off the spring?

Looks like the Milltek exhaust on my S5 has the same issue, and I'd rather be sure before cutting it up!

Not that i'm aware off :). Flaps working better then ever afaik but always good to give a squirt of wd40 or injection some heat resistance copper grease in rhat channel/tube to prevent unwanted metal noises when opening/closing the valve (on the other hand it is a good indicator they working 🤣).

[Omychron]

Not that i'm aware off :). Flaps working better then ever afaik but always good to give a squirt of wd40 or injection some heat resistance copper grease in rhat channel/tube to prevent unwanted metal noises when opening/closing the valve (on the other hand it is a good indicator they working 🤣).

Awesome, thanks!

[pipsovich]

Hello! I will use this thread for my problem.
I have a milltek exhaust with very much rattle from the left Side flap. Have replaced the motor with spring and no luck. Flap moves freely by hand. Also moves with the motor, of course.
My question: will removing the internal spring help with the rattle or is it only for making sure it does not get stuck?
It sounds really bad, and yes i am sure it is the flap and not something else.
Thanks.

[aistis72]

So i had this issue on my left tailpipe a year ago, meanly that the valve would not open.
I had grinded the lip a bit and in the end i got it sorted, no issues and normal behaving valve.
Untill i few weeks ago inspected my right valve...I'll be damned, now it is the right one that is blocked!!
I tried to contact Milltek, sended them video and explained what the malfunction is.....no help from them since then :(.

Anyway, so Milltek has this 'lock' feature, witch is basicly a spring that is pushing the valve upwards into a very thinny grove in the tailpipe.
Once you install your OEM actuator with the stock turning spring, that spring should counter force the milltek spring and freely open/close the valve.
.....In theory, but in reality the stock spring is not strong enough or wears out over time so the milltek spring is too strong and thus keep the valve locked (without you knowing it...and maybe risk unbalanced pressure in exhaust system. Afaik the ECU has a engine protection mode to always open the valve under heavy load...unless Milltek designs a valve that fails!!).

Anyways, since Milltek doesn't man up, looks i'll have to do it myself.
Does anybody know if that milltek spring would be located underneat the valve rod? There is this extra piece, i suspect it is a hallow tube containing a spring. About to grind the bastard off....

For your information, i had recently put my stock exahust on and OEM valves don't have this extra piece under the valve NOR does it need force to push the valve downards before opening. Not sure why Milltek added this in the first place (maybe for anti-rattling valve noise).

Added small movie of the blocked valve and the downwards pushing to open it. With my hand it works, but the stock spring isn't strong enough (sadely new spring isn't sold seperatly).
*nevermind the movie, it was too big and couldn't upload :(.

Thanks for sharing, I solved with wd40 one my flaps were stuck


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[Dasquade]

Thanks for sharing, I solved with wd40 one my flaps were stuck


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No problem...but keep in mind it is an indication stuff is getting cloud up (in the little cilinder/spring). You will need to be aware of it and you don't want it to become a 'service' item. Since the stock milltek is H....let me retype it....milltek is a little h setup (very small cut holes connecting left and right pipe)...i don't think it is healty running around with one bank being able to let out gasses/pressure easier then the other.
So my advice is, cut out the little spring witch really solves the stuck flap issues once and for all.

[pipsovich]

I did not remove the springs. I located the problem to the left Valve being loose , compared to the right valve which is silent. Looks like i have to get a new muffler........ Or can these valves be bought somewhere separately?

[Dasquade]

I did not remove the springs. I located the problem to the left Valve being loose , compared to the right valve which is silent. Looks like i have to get a new muffler........ Or can these valves be bought somewhere separately?

What you mean with 'loose'? Basicly it is just a rod with a flap bolted on.
From my talk with Milltek back in the days, they mentioned they don't make the flaps themself but supposed to be the same versions audi outsources and use on the stock exhaust. Clearly it isn't as stock doesn't have the springs under them and 'lock'.
Anyway, like mentioned, sorry but after all these years i drawn the conclusion Milltek is overpriced rubbish junk imho and not basing myself on only the failing flaps (junk designed/build H pipe....failing welds inside the resonators...fitment...).

[aistis72]

No problem...but keep in mind it is an indication stuff is getting cloud up (in the little cilinder/spring). You will need to be aware of it and you don't want it to become a 'service' item. Since the stock milltek is H....let me retype it....milltek is a little h setup (very small cut holes connecting left and right pipe)...i don't think it is healty running around with one bank being able to let out gasses/pressure easier then the other.
So my advice is, cut out the little spring witch really solves the stuck flap issues once and for all.

But I afraid to damage something, sorry for being noob) I would love to see video DIY)


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[mrpen1210]

Hi all, I just got my Milltek non resonated valvesonic exhaust installed last week on my 2017 S6 prestige and I found out that only 1 valve was open and the other was close. I drove my car a little bit see if there is anything change and after few miles around my house, both valves are now open but won’t close when I put in comfort mode. So anyone know how to fix it? Thank you.


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[Dasquade]

Hi all, I just got my Milltek non resonated valvesonic exhaust installed last week on my 2017 S6 prestige and I found out that only 1 valve was open and the other was close. I drove my car a little bit see if there is anything change and after few miles around my house, both valves are now open but won’t close when I put in comfort mode. So anyone know how to fix it? Thank you.


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Might want to try unplugging and replugging the connectors. Normally that resets the adaptation and the module will do a selfcheck for the limits (open close) by cycling the valve 3 times. It does that every x start ups.
If that doesnt fixes it, might want to unbolt the actuator with exhaust still on car (bitch to get off)...and cycle the milltek valve yourself if it opens/closes freely.
Maybe also try the actuators free from the exhaust but plugged it and manually open close them (through mmi or the dual esp pressing) to check if they work freely.

[phaphaphooey]

Could it be that S6/S7 only have one valve from the factory whereas the RS7 has both sides valved?

[mrpen1210]

Might want to try unplugging and replugging the connectors. Normally that resets the adaptation and the module will do a selfcheck for the limits (open close) by cycling the valve 3 times. It does that every x start ups.
If that doesnt fixes it, might want to unbolt the actuator with exhaust still on car (bitch to get off)...and cycle the milltek valve yourself if it opens/closes freely.
Maybe also try the actuators free from the exhaust but plugged it and manually open close them (through mmi or the dual esp pressing) to check if they work freely.

I’ll tell my mechanic to do it tomorrow and I’ll let you know thw result. Thank bro.


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[clkitx]

Hi there
I just installed a milltek catback non reso exhaust and I hear a very annoying metallic sound when decelerating at ±2500rpm
Here is a link to a video
https://www.dropbox.com/s/ahr924lddq...%2045.mov?dl=0

Possibly a DP failure ?

[Virtus5]

Might want to try unplugging and replugging the connectors. Normally that resets the adaptation and the module will do a selfcheck for the limits (open close) by cycling the valve 3 times. It does that every x start ups.
If that doesnt fixes it, might want to unbolt the actuator with exhaust still on car (bitch to get off)...and cycle the milltek valve yourself if it opens/closes freely.
Maybe also try the actuators free from the exhaust but plugged it and manually open close them (through mmi or the dual esp pressing) to check if they work freely.

Thank you for the original post!
I just realized that I have a similar issue.
The valve on the driver side doesn't open when I switch from comfort to dynamic at idle. Not sure if it is normal or not. I also wonder if it opens correctly while accelerating... (Stage 2 RS7 with downpipes)
I also have this cycle when it open/close 3 times whenever I start the car.