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Discussion Starter · #1 · (Edited)
Sorry for the length but I'm going to try and get the into out in the first post...

So doing the right thing and following the maintenance schedule to maintain the warranty, I performed a full brake fluid flush on my wife's 2019 Tiguan two weeks ago (first flush at the 3 year mark...also did the Haldex clutch fluid). I used a liter OEM VW dot4 class 6, iso...blah blah blah certified fluid from a local dealer along with about a half a liter of ATE SL.6 which has the same exact specs as the factory in a motive pressure bleeder bottle set to 12-13psi.

About a week and half into that flush my wife noticed a slight squeak/sigh type sound when one gently operates the brake pedal say in a parking lot or pulling into the garage. A quick Google search shows this seems to be common with MQB platform vehicles (VW, Audi, Porsche Macan's) and BMW's (found one there too) when a higher temp fluid such as ATE 200 is used. Now some of those Google search results were forums and videos and some reported the sound went away when they replaced with OEM fluid.

Started thinking that maybe that half a liter of ATE SL.6 fluid might be causing that noise so I bought a liter of OEM VW dot4 fluid from the dealer and did an entire flush yesterday....the noise remains. WTF!!

Dug a little deeper on the interwebs and I found a thread in the golfmk7 forum that one person said they tried multiple LV (low viscosity) including OEM and it continues. One said they switched to ATE SL.6 in their Atlas and the sound went away. Forums and videos below...






Sooooo...anyone else having this annoying sound after a flush? What fluids are you using?

I presume VW branded brake fluid is just an aftermarket brand like Pentosin, Febi, etc (one person on page 1 of the golfmk7 thread stated they used Pentosin LV dot4 which caused the issue).

In June I flushed my R32 with ATE SL.6 with no such issue and I'm tempted in ordering two 1 liter bottles and give her Tiguan a thorough flush to get the OEM VW fluid out.

Thoughts?


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Yeah try OEM fluid if you think thats the problem but my guess would be that maybe the system was not bled properly? People switching fluids means they had to redo the flush and maybe bled the system correctly at some point.

How exactly are you bleeding? Do you pump the pedal before applying pressure with the power bleeder?

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Discussion Starter · #4 · (Edited)
Low cost, zero risk move, not much effort.
What are you waiting for? Pull the trigger.
Get back to us, we may all learn something.

fat biker
I know... Going to wait until later this week and see if temps had anything to do with this as it's predicted to be around 60 Friday. It was quiet for a little over a week and then the temps dropped here mid last week and feel like that's when the sound started.

I'll report back

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Discussion Starter · #5 · (Edited)
Yeah try OEM fluid if you think thats the problem but my guess would be that maybe the system was not bled properly? People switching fluids means they had to redo the flush and maybe bled the system correctly at some point.

How exactly are you bleeding? Do you pump the pedal before applying pressure with the power bleeder?

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Technically not switching fluids. The first go around it was mostly VW fluid mixed with ATE SL.6 fluid that has the same classification rating. Second time I did the flush it was an entire liter of VW fluid. Again from what I understand almost no car manufacturer produces their own fluid and it's just rebranded aftermarket...hence why some aftermarket brands are listed as OEM on parts websites such as CPI, ECS and FCP.

As far as procedure, I'm following the service manual for the Tiguan except I'm keeping the bottle pressure at a little lower PSI which is fine and it'll just a little longer to bleed. To answer your question, no I'm not pumping the brake pedal before. I'm also bleeding FL, FR, RL, RR...again per the service manual.

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I would say this is most likely a case of correlation rather than causation.
The only ways I can thing a bleed would cause noise are:
a) fluid was spilled on the pad/rotor and has seeped into the pad changing the braking characteristictics
b) air in a line causing less braking force on one wheel.

a might be solved by thorough cleaning with brake cleaner spray and getting the pads nice an hot with some aggressive braking, basically the bedding process.
b would be another bleeding to resolve.
 

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I would say this is most likely a case of correlation rather than causation.
The only ways I can thing a bleed would cause noise are:
a) fluid was spilled on the pad/rotor and has seeped into the pad changing the braking characteristictics
b) air in a line causing less braking force on one wheel.

a might be solved by thorough cleaning with brake cleaner spray and getting the pads nice an hot with some aggressive braking, basically the bedding process.
b would be another bleeding to resolve.
I am not sure if I follow. The OP is experiencing a hissing noise coming from the brake pedal area as shown in videos attached in the original post. That would indicate that noise is being created somewhere at the pedal or master cylinder.

PS: Now I want to check my wifes Tiguan to see if it has this problem. I did brake fluid change in September but I dont drive that car much. I used Genuine VW/Audi fluid
 

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Discussion Starter · #8 ·
I am not sure if I follow. The OP is experiencing a hissing noise coming from the brake pedal area as shown in videos attached in the original post. That would indicate that noise is being created somewhere at the pedal or master cylinder.

PS: Now I want to check my wifes Tiguan to see if it has this problem. I did brake fluid change in September but I dont drive that car much. I used Genuine VW/Audi fluid
Thank you...was confused also.

And please if you get a moment...car running in park and gentle apply the brake on and off. If you cycle it quick it won't make the noise, just slowly on and off the pedal.

For haha's since everyone loves pictures, attached is the 1 liter bottle.

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I wonder if the issue is related to the ATE SL.6 fluid you used. Though it is a DOT4 fluid, it’s “low viscosity”, sometimes called DOT4 + or LV. It’s about 1/2 the viscosity (thinner) than what would be called standard DOT4.

I have a very similar “squeak” that comes from the booster/master cylinder as well but only very occasionally so I didn’t think much of it until now and it started shortly after I flushed my brakes with this ATE SL.6 fluid.

I’m now wondering if the low viscosity provides perhaps less/different lubrication to the seals in the master cylinder which is causing the squeaking?

I’m very anxious to hear how your flushing back to the OEM fluid affects things. I’m sure the OEM is a standard DOT4 and not the low-viscosity DOT4+ but I could be wrong. When you do the re-flush, it may take a while for the new fluid to work it’s way to replace the “old” fluid around all the seals (where the squeak is probably coming from).

…just my thoughts on this!

Please do keep this thread updated with your results!

Cheers,
DoC


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Discussion Starter · #10 · (Edited)
I wonder if the issue is related to the ATE SL.6 fluid you used. Though it is a DOT4 fluid, it’s “low viscosity”, sometimes called DOT4 + or LV. It’s about 1/2 the viscosity (thinner) than what would be called standard DOT4.

I have a very similar “squeak” that comes from the booster/master cylinder as well but only very occasionally so I didn’t think much of it until now and it started shortly after I flushed my brakes with this ATE SL.6 fluid.

I’m now wondering if the low viscosity provides perhaps less/different lubrication to the seals in the master cylinder which is causing the squeaking?

I’m very anxious to hear how your flushing back to the OEM fluid affects things. I’m sure the OEM is a standard DOT4 and not the low-viscosity DOT4+ but I could be wrong. When you do the re-flush, it may take a while for the new fluid to work it’s way to replace the “old” fluid around all the seals (where the squeak is probably coming from).

…just my thoughts on this!

Please do keep this thread updated with your results!

Cheers,
DoC


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Just to clear things up...I've flushed the braking system twice in the last two weeks, first flush was 1L VW mixed with about .5L ATE SL.6 (extra because I was afraid I was going to run out) and the second flush was 1L VW only.

The VW branded bottles I used are labeled DOT4 Class 6 that conforms to FMVSS no. 116, SAE J1704 and ISO 4925 (seen in photo above) which is the same certifications listed in the tech sheets from ATE's website for SL.6...that's what is throwing me off...literally the same fluid! Link to ATE SL.6's tech sheet: https://www.ate-brakes.com/media/2320/ate_td007_dot4-sl6-web.pdf

To top it off the VW service manual calls for "VW 501.14" which the VW bottle lists...
Font Terrestrial plant Screenshot Number Rectangle


I understand where you say "less lubrication" but I can also see the point of the need for low viscosity fluid especially for the electronic components within the braking system and them being subject to REALLY low environment temps. But from what I'm reading, others have used ATE 200 which isn't low viscosity and from the rip they're having issues with the noise...again in my wife's cars case, the timing seemed to be more inline with the temps dropping last week. With that said...low temps tend to thicken fluids which also goes to explain that some people from the reading stated they switched to a DOT5.1 fluid and the sounds went away AND DOT5.1 fluid is considered to be "very low-viscosity" fluid which would make more sense with colder temps to work better.

I'm sure its fine especially since I've done it twice with fluids meeting the requirements but its more annoying than anything when gently using the brakes. Hopefully like you said, maybe it takes a bit to work its way around the brake system though I would think the whole point of the flush is to replace the old fluid with new fluid. They're predicting mid 50's for Wednesday, Friday and Saturday so HOPING the sound changes on those days. I COULD also just take the car for a spirited drive and cook the brakes to heat the fluid up but I'll be patient and see what the warmer temps bring later this week.

Hoping to hear back from you guys to see if your Tiguan's are "experiencing" the same thing.
 

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Quick update. Took my wifes car for drive today and did not hear anything. But it was fairly warm close to 50F and raining. Will try to look listen for the sound in few days again. I have used the same OEM fluid you posted.

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Discussion Starter · #12 ·
Quick update. Took my wifes car for drive today and did not hear anything. But it was fairly warm close to 50F and raining. Will try to look listen for the sound in few days again. I have used the same OEM fluid you posted.

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Awesome... Thank you for checking!

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Awesome... Thank you for checking!

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Well ... I was able to reproduce that noise this morning. As you described the noise is there when lightly pressing on the pedal, e.i. parking or maneuvering through parking lot.
So I am in the same boat as you now :) and its definitely annoying.
I am going back to my initial theory that this has something to do with bleeding, not the actual fluid. I have always used genuine VW fluid and I have been bleeding brakes as per factory manual with a power bleeder(I do between 15-20psi). I even used quickjack, like you ... I know that part does not matter :)
 

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Discussion Starter · #14 ·
Well ... I was able to reproduce that noise this morning. As you described the noise is there when lightly pressing on the pedal, e.i. parking or maneuvering through parking lot.
So I am in the same boat as you now :) and its definitely annoying.
I am going back to my initial theory that this has something to do with bleeding, not the actual fluid. I have always used genuine VW fluid and I have been bleeding brakes as per factory manual with a power bleeder(I do between 15-20psi). I even used quickjack, like you ... I know that part does not matter :)
Sorry?? LOL

It sucks now that we know it's there. It's just odd...many have said changing out the fluid helped in there case but they were using ATE 200 which isn't low viscosity.

IF...IF warmer temps make it "go away" I'd almost put money on if that DOT5.1 fluid was used, it would "fix" this annoyance.

Again thank you!!

I'll keep you all posted later this week with my "testing".

BTW, the Quickjack setup is awesome for lifting the car up evenly.... I'd love a two post but don't have the height in the garage for it.

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It was pretty warm today ~58F and noise was there. I am going to remain stubborn and still insist this might be due to bleeding... not fluid :). I might get another 1L of fluid and try again over Christmas holidays. But I am curious to see how your experiment turns out.
 

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Hi Guys,

I'm on the same boat - I posted also on the golf forum so to recap. I have Tiguan 2017 - MY2018, and squeak started also after fluid replacement but about first month I wasn't focusing on that as I every time thought it is my wet shoe on brake pedal doing that noise then found it is brake pedal itself and since then it is driving me crazy. I changed fluid to original VW OEM DOT4 LV fluid replaced fully like 2 liters, after that once more time with VW OEM DOT 4 LV, then tried Ravenol DOT 4 LV and now I'm on Shell DOT 4 ESL with all those fluid pedal is still squeaking. Yesterday ordered Motul DOT 4 LV and also TRW DOT 5.1 ESP as last try. After that I'm afraid only replacement of master brake cylinder will solve this - or also booster could be the culprit really no clue. I have also used power bleeder at around 15 psi.

If you find something please update this thread I will do the same once will have something new.

Thanks,

David
 

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Discussion Starter · #17 · (Edited)
It was pretty warm today ~58F and noise was there. I am going to remain stubborn and still insist this might be due to bleeding... not fluid :). I might get another 1L of fluid and try again over Christmas holidays. But I am curious to see how your experiment turns out.
Haha...I'm on the other side of the fence and still think its the fluid because the power bleeder is so simple and practically error proof if you never run out of fluid in the reservoir.

I'm tempted to skip ATE SL.6 and go right to ATE Super DOT5.1 since its backwards compatible with DOT3/DOT4, has the same certifications and works better in lower temps.
 

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Discussion Starter · #18 · (Edited)
Hi Guys,

I'm on the same boat - I posted also on the golf forum so to recap. I have Tiguan 2017 - MY2018, and squeak started also after fluid replacement but about first month I wasn't focusing on that as I every time thought it is my wet shoe on brake pedal doing that noise then found it is brake pedal itself and since then it is driving me crazy. I changed fluid to original VW OEM DOT4 LV fluid replaced fully like 2 liters, after that once more time with VW OEM DOT 4 LV, then tried Ravenol DOT 4 LV and now I'm on Shell DOT 4 ESL with all those fluid pedal is still squeaking. Yesterday ordered Motul DOT 4 LV and also TRW DOT 5.1 ESP as last try. After that I'm afraid only replacement of master brake cylinder will solve this - or also booster could be the culprit really no clue. I have also used power bleeder at around 15 psi.

If you find something please update this thread I will do the same once will have something new.

Thanks,

David
Hi David...Thanks for chiming in!

Would you be willing to skip the Motul DOT4 fluid and go right to the TRW DOT5.1? I'm curious about the DOT5.1 fluid as a few posted up in the GolfMK7 forum that they switched to Motul DOT5.1 and the squeak went away.

Also any of you guys noticed that the bottom side of the master cylinder reservoir cap has the TRW branding on it? AND another thing...at least here in the States, anyone question why the first fluid change should happen at the 3 year mark and then 2 years after that? I've read that the DOT5.1 has a longer service interval though the fluid manufacturers state to follow vehicle manufacturers service interval.

Edit: TRW makes a DOT5.1 fluid...ECS sells it and listed at "OEM" on their site... https://www.ecstuning.com/b-trw-parts/dot-51-brake-fluid-1-liter/pfb532~trw/
 

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Hi David...Thanks for chiming in!

Would you be willing to skip the Motul DOT4 fluid and go right to the TRW DOT5.1? I'm curious about the DOT5.1 fluid as a few posted up in the GolfMK7 forum that they switched to Motul DOT5.1 and the squeak went away.

Also any of you guys noticed that the bottom side of the master cylinder reservoir cap has the TRW branding on it? AND another thing...at least here in the States, anyone question why the first fluid change should happen at the 3 year mark and then 2 years after that? I've read that the DOT5.1 has a longer service interval though the fluid manufacturers state to follow vehicle manufacturers service interval.

Edit: TRW makes a DOT5.1 fluid...ECS sells it and listed at "OEM" on their site... https://www.ecstuning.com/b-trw-parts/dot-51-brake-fluid-1-liter/pfb532~trw/
Hi VDoubleUVR6,

Sure I could do that and go with 5.1 right away, thing is that Motul have only one 5.1 which have viscosity 900 and I ordered TRW 5.1 ESP - PFB750 which has lower viscosity around 700 but I hope lubricity properties will be better than DOT4.

Yes exactly my master brake cylinder is made by TRW specifically it states TRW 8719 and it is TRW PML480 which is sold out everywhere currently. Original VW part is the same but price is 4x higher.

David
 

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Discussion Starter · #20 ·
Hi VDoubleUVR6,

Sure I could do that and go with 5.1 right away, thing is that Motul have only one 5.1 which have viscosity 900 and I ordered TRW 5.1 ESP - PFB750 which has lower viscosity around 700 but I hope lubricity properties will be better than DOT4.

Yes exactly my master brake cylinder is made by TRW specifically it states TRW 8719 and it is TRW PML480 which is sold out everywhere currently. Original VW part is the same but price is 4x higher.

David
I thinking the same with the even lower viscosity and lubricity properties like you said....very curious to hear about your results. I'm also hoping its just the fluid...just coincidental that the noise appeared after the flush and honestly don't think its a failing master cylinder.

Thanks again for the info!!
 
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