Help! Clutch pedal stuck to the floor

dieselmani

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2006 Jetta TDI MKV
Today I tried to bleed the clutch hydraulics manually. I pressed the pedal, blocked it with a long post pressed against the driver's seat, opened the slave bleeder, bled the brake fluid into a bottle, closed it again and raised the pedal. The instructions for this procedure are on myturbodiesel.com. I did that for 10+ times, no air. Just as I was ready to deduce that there is no air in the clutch hydraulics air bubbles started to appear, small at first, then more. I continued with the process for another 20+ pumps always making sure master cylinder reservoir is filled to the top. It seemed like the air bubbles are getting less and less, and at one point I had only solid fluid coming out of the slave cylinder nozzle, so I thought I'm practically almost done.
And then came the big surprise. Air bubbles reappeared, and with the last few pumps only foam, or frothy brake fluid came through the drain line. The pedal completely lost its tension and won't come back up at all and remains stuck to the floor. I'm clueless and don't know what caused the ultimate failure, or where to start to get the clutch working again. Thank you.
 
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Seatman

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Easier with a pressure bleeder, why were you bleeding it to start with?
 

Ol'Rattler

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Most likely you let the master cylinder get to low. You can not let the level get below the tap on the side of the reservoir which is about 1 inch below the full line.

Also, after you close the bleeder cycle the petal several times by hand. The first few pumps you will have to manually pull the petal up. If it is still spongy check the reservoir and repeat the process. You don't really need a pressure bleeder, but having another person to help is a VG idea.

The 3 commands you would give them are pump, hold and release. If they can follow your direction, the process is pretty easy peasy.............
 
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dieselmani

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I put in a new Sachs clutch and single mass flywheel kit at a local shop 10 months ago. At first everything worked like butter, but sometimes I would get into grind when shifting. It seemed like the clutch wouldn't engage properly. So I thought I got lazy not pressing the pedal down enough. But the problem wouldn't go away. Eventually, the clutch pedal got soft, and occasionally it would get stuck to the floor, especially after shifting between 1st and reverse while parking. So I thought air got somehow into the clutch hydraulics. I tried reverse bleeding to force the air out down from the bottom through the slave cylinder bleeder screw just like shown on youtube with an oil can filled with brake fluid. But that did not work at all and not a drop went into the hydraulics, everything went sideways, spilling into the engine room, or on the transmission housing, although I made sure the line is tightened on the slave cylinder nozzle secured with a zip tie.
Next, I tried to bleed the clutch hydraulics manually the way it is described on myturbodiesel.com by pressing the clutch, opening the screw etc., just like I posted in my original post. At the end only frothy brake fluid came out, the reservoir was filled to the top, but there is no pressure on the clutch pedal whatsoever. I can't pump any longer, because there is no pressure, pedal just implodes without any resistance straight to the floor. The first 20+ pumps it worked well, after that the pressure was gone. Thank you.
 
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dieselmani

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I just went outside and pumped the pedal several times. It stays down, no pressure or resistance. It seems like there is no more brake fluid in the hydraulics, just air. Reservoir is full.
 
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Seatman

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Another option is to run a pipe from the left front brake calliper bleed nipple to the slave, then as you pump the brakes gently it pushes any air up and out the reservoir.


Personally though, I find everything hydraulic on the mk4 is easier with a cheap pressure bleeder lol
 

Ol'Rattler

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Another option is to run a pipe from the left front brake calliper bleed nipple to the slave, then as you pump the brakes gently it pushes any air up and out the reservoir.
I like that idea a lot. Also, you can run the hose from the slave bleeder and back into the reservoir.
Personally though, I find everything hydraulic on the mk4 is easier with a cheap pressure bleeder lol
I made a pressure bleeder from an old reservoir cap, an air fitting, a regulator/air filter and my compressor. Not to bad except you have to watch the reservoir like a hawk and not let it get to low on fluid.
 
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dieselmani

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Thanks for the responses. Pumping through the slave with the help of the brakes seems like a good idea. But, like I said, I already tried pumping with an oil can filled with brake fluid through the slave bleeder and no fluid went through it. Pressure would build up and the fluid would go eventually sideways at the nozzle and not up the line. Don't know why it wouldn't work, but the reverse method of forcing air out through the slave didn't work for me.
I'm thinkin' of getting a vacuum pump from autozone tomorrow and trying to get that to work. They sell one OEM vacuum pump for $34 bucks, or does it have to be a Mityvac pump?
 
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dieselmani

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I tried a vacuum pump on the slave bleeder today and no brake fluid comes out through the bleeder. Pedal remains flat, because there is not a drop of brake fluid in the clutch hydraulics. What might be the reason for the fluid not to be able to flow down from the master reservoir? Master reservoir remains full, no loss of fluid noticed. Thanks.
 

GCBUG00

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Hartsville SC
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2000 Beetle
I tried a vacuum pump on the slave bleeder today and no brake fluid comes out through the bleeder. Pedal remains flat, because there is not a drop of brake fluid in the clutch hydraulics. What might be the reason for the fluid not to be able to flow down from the master reservoir? Master reservoir remains full, no loss of fluid noticed. Thanks.

Pedal doesn't return = air in the system.

Fluid not flowing thru the bleed screw with vacuum, make SURE the pedal is all the way up and the push rod is correctly connected to the pedal.

With the pedal down at all, the port is closed from reservoir, no fluid will easily pass. Push rod not fully locked into pedal, same as pedal not all the way up, port is closed.

This may not make sense until you try it but you don't need pressure to get an air bubble out of these systems with a piston/port master cylinder design.

Open bleed screw bleeding.

The sequence is the key.

1. Pedal up.
2. Open the bleed screw.
3. Push pedal slowly to the floor, hold.
4. Close bleed screw.
5. Lift pedal all the way up.

Repeat process, watching for steady stream of fluid, no bubbles. Test system. This works like a tire pump pumping up a tire.

Gary
 

dieselmani

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Thanks Garry. But on myturbodiesel.com the instructions say to press the pedal, hold (I did it with a post pressed against the driver's seat), then open the bleeder, let drain, close, and finally raise the pedal.
You are suggesting to open the bleeder first, then push down and hold...etc.

When I did it according to the sequence described on myturbodiesel.com it worked for 10+ pumps, then suddenly only frothy fluid came out full of air, then nothing. The pedal got basically sucked to the floor.

After that I tried the vacuum pump. Pedal was up, I opened the bleeder, pumped to get the suction pressure up and no fluid would get into the line.

Next, I just pumped the pedal 30+ times with the bleeder closed. I think I heard some fluid movement in the lines. With vacuum pump still attached and under suction pressure, I opened the bleeder and there was suddenly flow. At first, with a lot of air, then it got better. I released the suction, pumped it up again, and had solid fluid, but maybe for about 2"-3" distance from the bleeder nozzle. This got the pedal some 'ok' tension again and that's where I'm at right now. Thanks.
 

RoseBud68

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Find a friend to give you a hand. Let them pump the clutch pedal for you instead of this one man show.....Its advice its not working for you.
 

dieselmani

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Garry, where can I find the push rod at the pedal and how will I notice that it is not correctly connected to the pedal. Thanks.
 

Seatman

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Thanks for the responses. Pumping through the slave with the help of the brakes seems like a good idea. But, like I said, I already tried pumping with an oil can filled with brake fluid through the slave bleeder and no fluid went through it. Pressure would build up and the fluid would go eventually sideways at the nozzle and not up the line. Don't know why it wouldn't work, but the reverse method of forcing air out through the slave didn't work for me.
I'm thinkin' of getting a vacuum pump from autozone tomorrow and trying to get that to work. They sell one OEM vacuum pump for $34 bucks, or does it have to be a Mityvac pump?
Take the bleed nipple right out and check it's not blocked, I found I had to take mine out a few turns to actually get it properly open or nothing would come out even with the pressure bleeder hooked up. Not sure if it has some sort of rubber seal inside.
 

Seatman

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I like that idea a lot. Also, you can run the hose from the slave bleeder and back into the reservoir.

I made a pressure bleeder from an old reservoir cap, an air fitting, a regulator/air filter and my compressor. Not to bad except you have to watch the reservoir like a hawk and not let it get to low on fluid.

I like being able to cobble something together when needed but these pressure bleeders are so cheap now I just went with the proper made thing lol
 

dieselmani

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Thanks RoseBud68, I've got a vacuum pump, so this should work without any helpers. Thanks.
 

dieselmani

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Thanks Seatman, the slave bleeder isn't blocked as I've got fluid flow from time to time. The nozzle at the slave bleeder screw seems to work. The problem seems to be that there is no good through put altogether from the master cylinder, but as I pointed out, there are no visible leaks, and there is no loss of fluid. Thanks.
 
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dieselmani

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Maybe the last option is to get a motive pressure bleeder and try it from the top.
 

Scoutx

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Flushing brakes/clutch

I've found over time, that the best way, short of a pressure bleed, to flush the brakes/clutch is work the brake a few times to release the power brake and ABS storage (engine off) then open the bleeder and let gravity do the work. You MUST insure that you don't allow the fluid level to get too low as if you get air into the system then you've got problems. On some BMWs that means a rollback and a trip to the dealership.

This will not BLEED air from the brakes but will allow you to flush the brake fluid in any car that doesn't otherwise have an issue with the brake/clutch system. It's not the quickest way, but it is IMO the easiest and safest way. The problem with the standard pump and release method of bleeding brakes is the cylinder tends to build up a certain amount of crud beyond the normal stroke of the master cylinder and when you do your pump and release you run the seals over this crud possibly scaring them and causing an internal leak that will slowly allow the pedal to head to the floor as you hold pressure on the brakes (ie stop light).
 

dieselmani

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no improvemanet

Thanks everybody. I tried to bleed the clutch manually in the sequence Garry suggested in one of his posts above and I tried it according to the instructions on myturbodiesel.com, but the problem remains the same, meaning, the pedal is sticky and eventually goes to the floor and doesn't come back in the first gear and reverse. The others, or higher gears work ok.

At the same time when I opened the slave bleeder and pushed down the clutch pedal I left the vacuum pump connected to increase flow. Strangely enough, the vacuum pump by itself wouldn't draw any fluid, or insignificantly, although I pumped it up to -25 vac in Hg.

With the combo vacuum pump and pedal pumping I had only very foamy brake fluid in the line. After a few cycles the result improved, and the stream was solid brake fluid maybe for 1"-2" distance from the bleeder nozzle. When I did this a few cycles more, again, I would get very foamy fluid and after that some improvement. Is it possible that there is simply a very tiny whole in the line between Master Cylinder and Slave Cylinder, i.e. where the solid metal line connects to the flex line, that draws air. See attached picture. Thanks.

 
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Ol'Rattler

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I have no idea what your HUGE out of focus picture is.

Just a friendly reminder: Do not let the fluid level in the reservoir drop more than an inch or you will be pumping air back into the clutch hydraulic circuit.
 

Fix_Until_Broke

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When the clutch pedal is up - there is an open connection from the clutch slave cylinder to the brake fluid reservoir.

When the clutch pedal is moved down ~1" that connection is closed by the piston in the clutch master cylinder which forces the fluid down the hose to the clutch slave cylinder.

That's it - nothing more to it.

If you're continually getting air in the circuit (which it sound like you are) there's only a few things it can be.

1) It's not uncommon for a seal to seal under pressure "out", but leak under vacuum "in" which can let air in the circuit. Check the little o-rings on both sides of the clutch line and replace if necessary (they're really expensive $15)

2) Since you have a 5 speed, you can easily pull the slave cylinder out of the bellhousing and have the whole circuit in your hands to check for leaks, wiggle things, hold it up in the air and bleed it, etc.

3) You could have a bad/failing clutch master cylinder letting air in through the seals

4) You could have a leak in the hose between the reservoir and the clutch master cylinder allowing air in the circuit.
 

sparkplugg

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Baytown, Tx
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2013 JSW
Here is what I do:
Attach a tube to slave bleeder nipple, weighted at the other end that goes down into a container with brake fluid. Open bleeder a couple good turns while a helper pushes down on pedal. When flow stops, close nipple. Repeat this until all bubbles are gogoneWorks for me.
 

dieselmani

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Thanks Ol'Rattler. This picture shows the connection point between the flex line which is hooked up to the slave cylinder and the solid metal line which leads down from the master reservoir. I tried to go as close as possible to show the dark area right where these two lines connect. Do You see the dark area where the lines connect? It looks little bit like a spill of fluid, or perhaps a very small leak?
If it is a leak, it might be the explanation why I get frothy fluid flow for a number of pumps, or where air gets in. I don't know, that's why I posted the picture hoping maybe someone has seen this before. Thanks.
 

Seatman

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Thanks Ol'Rattler. This picture shows the connection point between the flex line which is hooked up to the slave cylinder and the solid metal line which leads down from the master reservoir. I tried to go as close as possible to show the dark area right where these two lines connect. Do You see the dark area where the lines connect? It looks little bit like a spill of fluid, or perhaps a very small leak?
If it is a leak, it might be the explanation why I get frothy fluid flow for a number of pumps, or where air gets in. I don't know, that's why I posted the picture hoping maybe someone has seen this before. Thanks.

Clean the pipe connection up, a bit of brake cleaner and cloth or that does the trick. Then you can check it again later after more pumping etc to see of it's wet again which would indicate a leak.
 
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