A4 B6 problems installing new clutch slave cylinder

[Tommy5150]

Hey guy,

Absolute disaster of a day...... went to change the clutch slave cylinder today around 2pm, seemed quiet easy and quick. One bolt, bracket connection hose, get air out of system and done...... got old one out very quickly maybe 10-15 minutes, went to put new one in and disaster..

Can not get the new one in compressed enough so that the hole lines up for the bolt... there is no room at all to get two hands in there tried from top and also from bottom no go. After the quick removal spent the next 5 hrs trying with no avail from the top I removed the water bottle for the coolant and with my right hand pulled the Slave into place but as soon as I moved my hand a bit to get the bolt in at the same time with the same hand it moved, the spring pushed it out and I could not hold it. Tried everything in every way with no luck. After that long my right arm is shot.

Can someone let me know how they managed to do it and get the screw in??? All the videos I seen on google show taking the old one off and then with the new one already in place. But not how they done it.

Such an easy job it seemed turned in to a disaster. I can nearly re build an engine in the time i spent trying to get that bastard in

Any advice would be very much appreciated

Thanks heaps guys

[EuroxS4]

Key is to get it in straight. I normally get it in and then hook up my line and bleed.

[Tommy5150]

Key is to get it in straight. I normally get it in and then hook up my line and bleed.

Hey Eurox,

What I did was pull the old one out and try to put the new one in without connecting the lines, opened breather too to make it easier. Because of limited room I come in from the right on an angle and then straighten it up (on the left is the casing from the trans, but Like I said my arm is finished from trying to pull it in, hold it and same time getting bolt in. With two hands would be easy just cant get the other hand in.

[old guy]

Put a screwdriver through the bolt hole and use it to lever the slave cylinder into place. The back edge of the slave will rest on the retaining lip. Remove the screwdriver and install the bolt. Easy peasy :-)

Scroll to the end of this DIY for a pic. Clicky click®️

[Tommy5150]

Put a screwdriver through the bolt hole and use it to lever the slave cylinder into place. The back edge of the slave will rest on the retaining lip. Remove the screwdriver and install the bolt. Easy peasy :-)

Hey OG,

Thanks heaps for the advice. Will try that technique first thing in the morning with the screwdriver Will let you know how I go hopefully will be good

[Tommy5150]

Hey OG,

Thanks heaps for the advice. Will try that technique first thing in the morning with the screwdriver Will let you know how I go hopefully will be good

Hey guys, ok so I managed to get the slave cylinder back in and tighten the bolt, thank god

But clutch not working now, was going to start to bleed but clutch just springs all the way to the floor when I push it and stays there. All the way down, then by hand I pull it and it springs all the way back up. but no pressure in between.

What have I done wrong? or not done? is this normal?

I thought that all I have to do is get in the car and pump the clutch up a few times, hold it down go outside and open breather valve let the air out and close again. repeat 7ish times and done

So now I dont know if I should bleed when there's no pressure in there. Something very important the DOT4 fluid tank at the top is pretty much empty only a few mm maybe 4mm (5/32") is left in it. Is this why I am getting no pressure? But the brakes seem to work fine pedal is under pressure.

So not sure what to do now or Eurox if you have any advice please

[old guy]

The clutch pedal springs back up because of the overtravel return spring underneath the clutch pedal.

The brake fluid reservoir has a separate compartment for the clutch master cylinder fluid supply. The top is open, so when you fill the brake fluid reservoir, the fluid spills over into the clutch supply compartment. This is a safety feature. It prevents total brake failure in the event of fluid loss from the clutch.

You will need to refill the brake fluid reservoir before you can bleed the clutch. Once you start bleeding it will be important that you keep the brake fluid reservoir at least 2/3 full.

[Tommy5150]

The clutch pedal springs back up because of the overtravel return spring underneath the clutch pedal.

The brake fluid reservoir has a separate compartment for the clutch master cylinder fluid supply. The top is open, so when you fill the brake fluid reservoir, the fluid spills over into the clutch supply compartment. This is a safety feature. It prevents total brake failure in the event of fluid loss from the clutch.

You will need to refill the brake fluid reservoir before you can bleed the clutch. Once you start bleeding it will be important that you keep the brake fluid reservoir at least 2/3 full.

Hey old guy,

Thanks heaps for the advice I've never done a clutch slave or master cylinder so was not sure if I could get away with doing it now and just topping up the tank tomorrow. But makes sense that cause of nearly 0 fluid in the tank I can't get any pressure, I guess it's just air in there.

Thanks heaps again.

PS great bit of info on the slave cylinder replacement that you posted yesterday

[jjvwg]

It’s slightly concerning you’re having so much trouble with it even with the line being not attached. Is the push rod moving freely in the cylinder outside of the car? If it hasnt been mentioned yet, put a little grease on the boot where it rests in the bell housing to make it slide in easier as well.


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[Tommy5150]

It’s slightly concerning you’re having so much trouble with it even with the line being not attached. Is the push rod moving freely in the cylinder outside of the car? If it hasnt been mentioned yet, put a little grease on the boot where it rests in the bell housing to make it slide in easier as well.


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Thankfully I got it in today. Just don't have DOT4 fluid. So will finish it tomorrow. Yeah the cylinder was moving freely it was fine, not sure why it took me so long yesterday. Old guy sent a great link over so used the screwdriver and also greased it up a bit. So glad I got it done today. Main issue I was having yesterday I couldn't get it compressed enough for it to sit in behind the little nub to hold it in place while I get the screw in. But practice and experience makes perfect so will be a hell of a lot wiser next time thanks also to all your help

[jjvwg]

Glad to hear you got it in. Chances are you didn’t get the rod in the dimple on the clutch fork and that wasn’t letting it fully seat.


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[Tommy5150]

Glad to hear you got it in. Chances are you didn’t get the rod in the dimple on the clutch fork and that wasn’t letting it fully seat.


Sent from my iPhone using Audizine Forum

Yeah I'm so glad I got it done. At first I though they gave me the wrong part and it was longer hahaha check it with the original and it was the same. Was bizarre that I had so many issues with it. But I do it again I will be allot wiser

[Cybersombosis]

I reverse bleed when there is only one person available. Has worked many times for me.

[Tommy5150]

I reverse bleed when there is only one person available. Has worked many times for me.

hey Cybersombosis,

wow great vid thanks. Interesting doing it in reverse. I might try to do it that way. Was going to do it today forgot it's Sunday and everything is closed here. So tomorrow (Monday) it is.

[rollerton]

Man, I feel ya. Had all these same problems recently and I've been doing this for decades. I fiddle with the slave a little bit, but if it looks like it'll be a big hassle - like they occasionally are- I compress the slave slightly and hold the rod 1-2" compressed with some cloth friction/electrical tape. It only needs to stay compressed that inch or so to make the job 100% easier. If you try and keep it mostly or all the way compressed it'll be harder. Get the slave halfway seated where it needs it be and just rip the tape off.
Good luck on the bleeding- when I did this recently I found the clutch master must have gotten some kind of weird air lock or clog or something as it would NOT make pressure. It was a situation where it was perfectly fine, then it wasn't. Removed from car and it worked perfect, reinstalled and won't make pressure. Why? NO IDEA. So I just replaced that also, and everything worked great.
But if you have a problem bleeding a vacuum pump (even a crappy hand pump) is a SUPER great tool for this. It's not rocket science, and from what I've learned these jobs *should* be pretty easy, and if it isn't working there's something wrong. In the past, and even this last time, when everything is working the way it's supposed to bleeding the clutch should only take minutes.

[Tommy5150]

Man, I feel ya. Had all these same problems recently and I've been doing this for decades. I fiddle with the slave a little bit, but if it looks like it'll be a big hassle - like they occasionally are- I compress the slave slightly and hold the rod 1-2" compressed with some cloth friction/electrical tape. It only needs to stay compressed that inch or so to make the job 100% easier. If you try and keep it mostly or all the way compressed it'll be harder. Get the slave halfway seated where it needs it be and just rip the tape off.
Good luck on the bleeding- when I did this recently I found the clutch master must have gotten some kind of weird air lock or clog or something as it would NOT make pressure. It was a situation where it was perfectly fine, then it wasn't. Removed from car and it worked perfect, reinstalled and won't make pressure. Why? NO IDEA. So I just replaced that also, and everything worked great.
But if you have a problem bleeding a vacuum pump (even a crappy hand pump) is a SUPER great tool for this. It's not rocket science, and from what I've learned these jobs *should* be pretty easy, and if it isn't working there's something wrong. In the past, and even this last time, when everything is working the way it's supposed to bleeding the clutch should only take minutes.

Hey rollerton,

You know I was thinking something similar but when I tried it it didn't work. I tried to zip tie the slave all the way but had an issue getting the slave all the way in as the zip tie it seems was in the way. So I took it off. On the second day after getting advice from old guy managed to get it pretty much most of the way and the last little bit done with a screwdriver just to get it behind that small metal lip bit which it sits behind. So one it was there was cheering getting the bolt in was sweet after that. But sounds like a good way to get it done with a bit of thin cloth. Bleeding should be cool I've done brakes and stuff before so confident will be fine. Gonna try the reverse bleed Cybersombosis posted, pumping the fluid through the bleeder valve on the slave up into the tank, should easily push all the air bubbles up. Looked interesting and pretty straight forward considering I'll be doing it by myself. Hopefully won't have to replace the master cylinder on the clutch, but the luck I've had lately would not be surprised if it did F up on me hahaha. We'll see I'll let all you boys know tomorrow. Need the car for getting around. Currently have 3 cars there all in the process of fixing something so their all out of order at the moment. So hoping my luck changes and I get at least 2 cars up and running tomorrow, the A4 B6 and the A4 B7 Avant TDI. Fingers crossed. Yeah I get ya I went to bleed it when I got the slave in but forgot I didn't have any Brake fluid, what I was sure I has was already gone hahaha.

Was replacing the master cylinder pretty straight forward??

[rollerton]

Hey rollerton,

Was replacing the master cylinder pretty straight forward??

Yeah, it's more or less exactly how it looks. Just a broken neck position working under the pedals for a little bit getting it swapped. The big HASSLE with the master typically is getting the slave line in and fully seated. That junction is really perfectly positioned right under/ behind the brake booster. It could be buried just a little worse, but not much!
I usually try and have someone sort of hold the end of the line in the middle of the hole- just using a long pry bar type thing to hold it in place with a little pressure- as I push the master up into position. I think on one 6 speed swap I did It was just a total PITA so I actually got desperate and clicked the slave line into the master and fed it up through the whole from under the dash! It was either that or remove the booster, and I really didn't feel like doing that.
Need a good light under there for sure if you end up having to do it.

[Tommy5150]

Yeah, it's more or less exactly how it looks. Just a broken neck position working under the pedals for a little bit getting it swapped. The big HASSLE with the master typically is getting the slave line in and fully seated. That junction is really perfectly positioned right under/ behind the brake booster. It could be buried just a little worse, but not much!
I usually try and have someone sort of hold the end of the line in the middle of the hole- just using a long pry bar type thing to hold it in place with a little pressure- as I push the master up into position. I think on one 6 speed swap I did It was just a total PITA so I actually got desperate and clicked the slave line into the master and fed it up through the whole from under the dash! It was either that or remove the booster, and I really didn't feel like doing that.
Need a good light under there for sure if you end up having to do it.

Cool thanks. I just did the bleed today and looks like all good. got nice pressure in the clutch, gears are changing smoothly. Took it for a 100 mile test drive today after I finished the bleed. What I did find strange that the reverse bleed technique didn't work as the small pump I got wasn't strong enough to push it up, But I can see it working. I will be ordering a Sealey oil Pump which I will use in the future for these kinds of things.

That master sounds like a real pain in the ass job.

[Tommy5150]

Hey guys,

Does anyone know why the clutch sometimes doesn't return 100% of the way?

I drove about 300miles and out of that happened twice when I held the clutch in for a longer period of time, then released it, it seemed to stick a bit. Returned 2/3 or the way and the last bit had to pull the pedal with my foot to bring it up the last little bit. Then didn't do it again. Clutch is good under pressure not loose at all. Gears changing nice and smoothly when clutch is engaged.

Does anyone know what would cause a clutch to stick and do this sometimes?

[Cybersombosis]

You need to bleed your clutch again. What I do with the reverse bleed is open the bleed screw until the fluid starts dripping out then put the tube on the nipple then start pumping. Be careful not to overfill the reservoir.

How did you bleed the clutch the first time?

[Tommy5150]

You need to bleed your clutch again. What I do with the reverse bleed is open the bleed screw until the fluid starts dripping out then put the tube on the nipple then start pumping. Be careful not to overfill the reservoir.

How did you bleed the clutch the first time?

I tried the reverse bleed but could not get a strong enough pump to push the fluid up. So I did it the normal way by topping up the container, pumping clutch 10 times, holding clutch all the way down and then opening the bleeder valve about 1/3 turn. Then closing bleeder and pumping again. Did that over and over about 7 times. Clutch was nice and tight so thought I had it good.

When doing this I did open the bleeder valve a bit more a couple of times but every time I did that all the pressure in the clutch disappeared. So I'm assuming it was opened too much.

But when I did bleed it I got it to a point where I had fluid coming out and slowly dripping. There was no bubbles or air or anything like that coming out of bleeder valve so I thought I had it done...?

Weird thing is it only slightly sticks once every 500 pushes or so. Then when I pop it out with my foot it doesn't do it again. That is weird cause if there's something wrong I would expect it to happen all the time or more often that once in a long while.

[old guy]

The clutch pedal should have an over center spring that returns the pedal to the full up position. Make sure yours is installed correctly and working properly. Clicky click®️

[Cybersombosis]

All I can say is try again and loosen the bleed screw more. I used a small can like in the video and it worked for me. You don’t need anything powerful. If you can’t get flow with a small oil can like that, there is something blocking the passageway.

[Tommy5150]

The clutch pedal should have an over center spring that returns the pedal to the full up position. Make sure yours is installed correctly and working properly. Clicky click®️

Hey OG, Thanks will check it out and have a look. Found it in parts catalog

[Tommy5150]

All I can say is try again and loosen the bleed screw more. I used a small can like in the video and it worked for me. You don’t need anything powerful. If you can’t get flow with a small oil can like that, there is something blocking the passageway.

Ok will do, I bought a spray bottle with top pump (photo attached) to use, all I could find here quickly. I have got a sealey TP05 ordered but wont be here for a couple of days. I guessing the pump in the oil can is probably stronger to what the bottle I got is maybe? anyway we'll see how I go

[old guy]

Clicky click®️

[Tommy5150]

Clicky click®️

As always Legend mate! thanks for the link

[Tommy5150]

Hey boys, need some help. Discovered that the master cylinder on the clutch is leaking so changing it out.

Got everything out ok was not too bad, but am dying here trying to get the new master grommet clip back in. Just doesn't seem to wanna go back in it's getting wedged between the firewall metal, how do you reach it under the brake cylinder cant get my hand in there.

Any advice?

[Tommy5150]

Ok, total 8 hours later managed to get everything done new master in, everything bled and clutch working like a charm, feels so good now totally different feel. There were so many things that on this job that just wouldn't go..... I've done engine rebuilds, clutch chances, so many things but this one was by FAR the most complicated repair i've done. Hence the 8 hrs I was swearing so much throughout hahaha I can laugh now. Was not funny when I was doing it. I spent hours and hours reading up different threads and trying to find videos but doesn't matter how much I read nothing would of prepared me for this clutch master today. Main thread that helped me read about it was this one. Big up to 4BiddnA4 for posting it

First this that took some time was getting the clip out of the back of the pedal for the master, managed to work it out at the end, then I had problems seating the new master in the correct place to get the bolts in and the metal connector in the whole that from the firewall. Took more than a couple of attempts to properly seat the new master and had to take in out and back in a couple of times, the last time lost the little clip somewhere between fitting it. So had to full everything apart again including pulling the pedal clip and spring. But as they say practice makes perfect. Then lastly the little metal clip was a real B***H cause of not room to put my hand under brake cylinder and between ECU box. But mastered everything at the end. Big help was removing the drivers seat and working laying down with my feet up on the back seats.

I am so confident now if I was to do this job again I would have it all done so quick in maybe an hour / hour and a half. 2 to 2 and a half hrs for both slave and master

So chuffed that I got it done and all is sweet

[old guy]

Nice work!

[Tommy5150]

Nice work!

Thnaks

[Tommy5150]

Nice work!

Hey OG, Not sure if I spoke too soon..... I checked my work today and looking under the steering wheel I found on the new master cylinder that when I pushed the clutch in all the way with my hand and released it one drop of brake fluid came out. Is it supposed to do that I'm assuming not considering it's brand new? It does not leak when it just sitting there but seems as if when I push it in only when it comes out it brings with it a drop of fluid.

Clutch works good no problem there nor does it stick anymore.

[old guy]

Can you tell if the leak is coming from the hard line connection or the push rod end?

[Tommy5150]

Can you tell if the leak is coming from the hard line connection or the push rod end?

It is coming from the push rod end that's facing the rear of the car. When you poke your head under and push the clutch in is fine doesn't leak but as soon as you release the clutch a bit of oil not even a drop comes out as the little round rod push thing comes back out and brings the clutch into it's normal out position. Only maybe half a drop each time every-time the clutch is released.

I've attached a photo and tried to highlight with a red ring where the fluid is coming out of. But yeah it's the round push thingy at the end of the rod coming from the clutch pedal

Weird thing is clutch is nice and firm.

[old guy]

It's leaking past the compression cup seal. I would recommend using a small rag to soak up the drips and monitor the leakage over the next few days. I suspect the leak will stop after the seal wears in. If not, you get to stand on your head underneath the dash again and replace the master cylinder :-(

[Tommy5150]

It's leaking past the compression cup seal. I would recommend using a small rag to soak up the drips and monitor the leakage over the next few days. I suspect the leak will stop after the seal wears in. If not, you get to stand on your head underneath the dash again and replace the master cylinder :-(

ok cool. Will monitor it and see, hopefully it stops. fingers crossed. Many thanks as always

[Tommy5150]

It's leaking past the compression cup seal. I would recommend using a small rag to soak up the drips and monitor the leakage over the next few days. I suspect the leak will stop after the seal wears in. If not, you get to stand on your head underneath the dash again and replace the master cylinder :-(

Hey Old Guy, Just thought I'd let you know all is good with the new Clutch Master, just like you said it self sealed which is great. So happy thanks heaps

Can I ask you do you kno anything about the fuel trim measuring banks in VCDS mb32 & 33? What does it tell me if mb32 first box is 0% always and the second is -18%? Does that mean it's running rich? or do I have an intake leak. It's on a 1.4 16v engine.

[old guy]

Here's a little info that might help: Clicky click®️

[Tommy5150]

Here's a little info that might help: Clicky click®️

Hey Old guy thank heaps for the link. Great read.

Managed to get another working throttle body (TB) today and tried to swap it over to see if it improves and fixes the problem... it did not work, same problem as before so problem is not in the TB. Looked at the MAF sensor as I had a look at the intake manifold pressure G71 and it was around 880mBar at idle and it seemed like it did not work. So I put a new one in and again did not fix anything. New MAF reading was about 450 mbar. It did run a bit better but still very low RPM 500 - 550 - 650. I then looked at the main Lambda before the Cat in the engine and it seemed to me like it was not working. In one of the measuring banks cant remember which one now showed the Lambda B1S1 at -25% that did not move. So I think the engine is running too rich. So ordered a new one should be in tomorrow will try it. And also am thinking I will pull the head tomorrow morning too just to see what it looks like from the inside and see whats happening if anything. I think I'm getting closer to finding the problem hopefully 🤞 this car is an absolute nightmare by far the worst I've ever had.....

Any advice on what else I should/can check from your experience?