2013 Audi S4 clutch pedal to the floor after brake job

[Kiono_S4]

Been using the search feature and found multiple clutch pedal to the floor issues but wanted to get the expert opinion on my situation:

Performed a pad/rotor swap on my 2013 Audi S4, after the job was done I realized I left a bungie cord hanging in the front wheel area so turned on the car (clutch behaved normally at this time), turned the steering wheel to get easy access to the area. I removed the cord and straightened the wheels, turned off the car and just by habit I hit the clutch again and it sank right to the floor, brakes feel great but there is absolutely no pressure in the clutch. Checked the fluid levels in the brake reservoir and they look fine (granted, its a pain in the butt to see the actual level due to the colors). I got under the car and took the covers off, discovered I had signs of leaking fluid in various areas at the bottom of the transmission, near the clutch slave cylinder, and at the rubber hose that connects to the master. I wiped it all off and left it over night, didn't see much leakage the next morning although the below area had a bit of a wet look to it, as well as wetness at the upper end of this hose.




I completed the rear pads/rotors that morning and moved on to the new problem. I decided to try bleeding the clutch and read the various helpful threads on this forum. I didn't have access to a power bleeder so attempted a gravity bleed, as well as using a brake bleed tool (hand operated vacuum pump), with absolutely no success (the car was level), I could not get any fluid out during the bleed, all I got was hissing air whenever I opened the bleed valve, the reservoir remained above the min mark at all times. During the course of the bleed I attempted to add more brake fluid and within a few minutes saw that the majority of it to be leaking from the black access port shown in the first picture.

Are these symptoms consistent with a clutch slave cylinder failure?
Is it possible that the brake fluid reservoir was over filled?
Why is the fluid leaking from the observed area?
Is there any possibility the pressure plate/clutch disc/fly wheel got covered in brake fluid?

I am weighing my options between towing the car to a shop for a professional diagnosis or replacing the clutch slave cylinder and the hose leading to the master, which would mean I invest in a power bleeder (any recommendations on which one to get?).

Be gentle, thanks in advance for reading.

[maksym]

He-he. Did not read the whole saga, but what is not obvious is that the fluid reservoir has two chambers- for the brakes and for the clutch. The clutch would not bleed unless the fluid in the reservoir is almost all the way to the top. That is, if you disconnected the clutch line - there is a good chance the clutch part of the reservoir is still empty.

Edit: I see you mention a leak. You can take the slave out and inspect for leaks - it is held in place by a single screw. Unscrew it and gently pull it out. Never blew mine, but If you blew a seal - yes, the fluid will drip out of flywheel access hole. It is super easy to replace though. Other than that you could have ruptured the line - but it would not drip into transmission.



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[maksym]

I think it is not likely that you sprayed the fluid on the clutch if the slave indeed blown - there is pressure fork in the way. I guess you can try sticking a boroscope in the hole?


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[Kiono_S4]

Thanks, I’ll pull the slave to inspect and scope.

[maksym]

Thanks, I’ll pull the slave to inspect and scope.

Just don’t depress the clutch pedal when it’s out or you will definitely blow it.


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[wes8398]

OP, read YOUR story but haven't read any other replies. My first inclination is that this isn't a failed slave but rather a blown line or leak at a connection point. You wont see the fluid loss in the reservoir because it splits off somewhere down below of the opening. So if you blew a brake line, you wouldn't lose your clutch, and vice versa. I'd guess that if you over-filled the reservoir up to the brim and then let it sit (or operated your clutch pedal), you'd probably see the fluid level drop until it reaches that split. FYI - this might be a sign that you're due for some (really awesome and inexpensive) upgrades. Stainless clutch line (delay valve delete) and a JXB extended slave are calling your name. The JXB shift plate and short shift adapter thing are fucking awesome as well. Dooooo it.

[maksym]

OP, read YOUR story but haven't read any other replies. My first inclination is that this isn't a failed slave but rather a blown line or leak at a connection point. You wont see the fluid loss in the reservoir because it splits off somewhere down below of the opening. So if you blew a brake line, you wouldn't lose your clutch, and vice versa. I'd guess that if you over-filled the reservoir up to the brim and then let it sit (or operated your clutch pedal), you'd probably see the fluid level drop until it reaches that split. FYI - this might be a sign that you're due for some (really awesome and inexpensive) upgrades. Stainless clutch line (delay valve delete) and a JXB extended slave are calling your name. The JXB shift plate and short shift adapter thing are fucking awesome as well. Dooooo it.

Why would it drip from the tranny access hole though? Maybe he blew both by over pressurizing the tank?


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[wes8398]

Why would it drip from the tranny access hole though? Maybe he blew both by over pressurizing the tank?


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Pictures don't load on my work computers, so I missed that part. In agreement that it's likely a blown slave seal, in that case! JXB extended slave to the rescue, for sure! But also replace that clutch line/delay valve. And the shifter base.

[Kiono_S4]

Why would it drip from the tranny access hole though? Maybe he blew both by over pressurizing the tank?


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I found some time to work on this further this afternoon as the new slave cylinder arrived. That was definitely a problem, there were all these broken plastic pieces inside of the rubber boot. The leaking from the tranny access hole stopped after the new one went in and it was looking good, even got some feeling back in the clutch towards the end, unfortunately on my last bleed cycle I noticed the metallic line running to the slave had a drop of brake fluid at the loop, followed it up and sure enough that rubber hose is also leaking. Regrettably I chose not to get the upgrades wes suggesting... the replacement stainless steel line is on its way...

[maksym]

I found some time to work on this further this afternoon as the new slave cylinder arrived. That was definitely a problem, there were all these broken plastic pieces inside of the rubber boot. The leaking from the tranny access hole stopped after the new one went in and it was looking good, even got some feeling back in the clutch towards the end, unfortunately on my last bleed cycle I noticed the metallic line running to the slave had a drop of brake fluid at the loop, followed it up and sure enough that rubber hose is also leaking. Regrettably I chose not to get the upgrades wes suggesting... the replacement stainless steel line is on its way...

That’s a bummer! What was the pressure on your bleeder? I’ve blew the seals on the master on my Accord using the foot method but yet have to rupture the line on Audi. Then again, I was using the vacuum, not the pressure thingy.


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[Kiono_S4]

That’s a bummer! What was the pressure on your bleeder? I’ve blew the seals on the master on my Accord using the foot method but yet have to rupture the line on Audi. Then again, I was using the vacuum, not the pressure thingy.


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I was between 5-7 psi on my power bleeder, I did have a suspicion that hose was going to be an issue when I got under the car the first time but how could TWO components go... oh well, more responsive clutch here I come! I still don't understand how I over pressurized the clutch system, I had the brake reservoir cap off the whole time when doing the brakes.

[maksym]

I was between 5-7 psi on my power bleeder, I did have a suspicion that hose was going to be an issue when I got under the car the first time but how could TWO components go... oh well, more responsive clutch here I come! I still don't understand how I over pressurized the clutch system, I had the brake reservoir cap off the whole time when doing the brakes.

Oh, so your cap was off and you blew the slave before you even got to use the tool? That’s above my pay grade :) I can only assume it’s somewhat unrelated and your clutch is worn out allowing for too much travel on the slave. How is your starting? Do you have to depress the clutch real hard?


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[Kiono_S4]

Bizzaro - I’ve never had any clutch or starting issues, this is the first issue I’ve had since I got the car 8 years ago.

[Kiono_S4]

Thanks - slave and new line did it. Much appreciated for the feedback!

[ColoradoB5]

Kiono_S4, thanks for posting about your journey with the clutch slave cylinder. This just happened to me on my manual 2014 S4 as well...at least it looks to be the same. I'm going to get it up on jacks this evening and take off the covers and see if I have the same issue you did. Just out of curiosity, what slave cylinder and new clutch line did you go with? I'm going to do some research, but I was curious how satisfied you are with your purchase.

[M3Armand]

@Kiono_S4 Sorry to revive this. I literally got the same issue and I think I've narrowed it down to the slave cylinder also. I see no leaks around the lines.

But here's a noobe/dumb question for you. What is the access port for? Just like yours, this is where I see leaks on mine. See pic below. I took off the access port, but I don't know what it reveals. :( What is it covering? There's oil all over where I put the red marks.

We have 155k miles in our stock S5 clutch. APR Stage 1 since 139k miles. I noticed the clutch "shudder" 30k miles or even more ago (well before the APR tune). I was hoping that the APR would speed up the clutch wear process so we could upgrade, but it hasn't yet. The clutch doesn't slip (yet). If it would slip, I would assume it would do so in 6th first.

I came across this thread since the clutch pedal fell to the floor and stayed there (no spring back option). I'm trying to determine (without replacing both), if it's the master or slave cylinder. No line leaks visible. No leaks visible around the slave cylinder. Using a stool, I pretty much stood over the car, stuck my head near the washer fluid reservoir and saw no leaks around the master cylinder connections (as much as I could see) behind the CPU box. The footwell floor around the clutch pedal is dry = no master cylinder leaks inside the car either.

But I did see leaks near the access cover area as shown in the pic. I'm not sure how they got there. I filled the brake reservoir completely to the top and put a pressure bleeder on at 12 psi. This is the typical setting I use when bleeding the brakes. I opened the slave cylinder bleeder and nothing comes out. I pumped the master cylinder by hand and it started to go back up. Unless someone can correct me, this tells me that the master cylinder is still good. I kept pumping the clutch by hand (ok, I had the wife do it while I watched what happened underneath the car). Fluid eventually came out of the slave cyl bleeder. It was really dark so I refilled the brake reservoir some more and repeated the process until the fluid coming out of the slave was clear.

So this is the part where I caught up to your thread. I'll remove the slave cylinder now and hope to see it disintegrate (confirming that it was the broken piece) and also hope to see leakage coming out of it.

[M3Armand]

Confirmed...the slave cylinder was leaking on the inside. It was falling apart as I was pulling it out and fluid started leaking. So I pushed it back in (so it doesn't leak in my garage floor) until I get the new part in this week, hopefully.

[maksym]

Confirmed...the slave cylinder was leaking on the inside. It was falling apart as I was pulling it out and fluid started leaking. So I pushed it back in (so it doesn't leak in my garage floor) until I get the new part in this week, hopefully.

The access port in your picture is used to access bolts that hold the flywheel and clutch together. The oil in that area could be fluid from the clutch slave, oil from the rear main seal or crank, or could be oil or steering fluid dripping from above just because it is the lowest point of power train. If you take it off, you should at least see if it’s coming from the inside or outside and from the front or rear of the car.


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[M3Armand]

The access port in your picture is used to access bolts that hold the flywheel and clutch together. ...

Another dumb question from me... so why would we need access to that? Is the access needed for a clutch change? Or is it for some form of adjustment between the flywheel and clutch? Thanks in advance!

[maksym]

Another dumb question from me... so why would we need access to that? Is the access needed for a clutch change? Or is it for some form of adjustment between the flywheel and clutch? Thanks in advance!

Yes, these bolts need to be undone when separating transmission from the engine, which is needed when changing clutch and working on transmission in general.


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