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Go Back   TDIClub Forums > TDI Model Specific Discussions Areas > VW MKV-A5 Golf/Jettas

VW MKV-A5 Golf/Jettas Discussions area for A5/MkV Jetta/Golf (2005/2006 PD and 2009 CR).

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Old May 15th, 2018, 13:01   #1
spatuality
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Join Date: Nov 2010
Location: Ontario, Canada
Fuel Economy: 5.8L/100KM
Default Clutch cylinders or brake booster

My car is still recovering from having the transmission explode due to a diff pin walkout failure.

Transmission replaced, car assembled, went to start the car.

Clutch pops to the floor with the car off, and has to be raised by hand. Like there is no hydraulic pressure at all. Just a spring to the floor.

(I started it anyways, and it ran fine for a minute with new smf/clutch. No change to clutch pedal on the floor)

Tried bleeding for about an hour. Manual 2 person process.

At first a bit of fluid came out, then just air. No change at all to the pedal.

Pulled the slave cylinder, and there's a fluid bubbling gurgling noise when I press in the slave cylinder by hand.

It sound like its coming from the brake booster. But from reading here, the master is much more likely to be bad.

I saw a drip of brake fluid under where the brake fluid reservoir attached to the brake booster. But that might of just been from me adding fluid a minute before, to make sure the system wasn't sucking air.

Here's pictures and a video of the brake booster and slave cylinder being pushed in.

Any ideas what went wrong here?










Last edited by spatuality; May 15th, 2018 at 13:05.
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Old May 15th, 2018, 13:54   #2
rallywagon
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Did you accidentally blow the piston out of the slave cylinder?.... Is the throw-out lever and bearing in position for the slave cylinder piston to actuate them?

I did this same job last weekend. I held the throw-out lever in place with a cable tie until I had the bell housing bolted in place.
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Old May 15th, 2018, 15:02   #3
spatuality
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The throwout lever is visible right up close to the slave opening in the housing. It looks like it's in the right spot.

The slave cylinder being popped out I didn't consider. How to check and fix this?

I did play with the slave cylinder quite a bit while it was out of the housing. Pushed it in, let the spring pressure push it out. I actually just tried bleeding with the slave in my hand. No difference.
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Old May 15th, 2018, 16:17   #4
rallywagon
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Default Bleeding Then...

Does your slave piston still have the nylon ball on the end? If so...

Sounds like you have all the pieces. Mount the slave, fill up the brake fluid reservoir and bleed...
- close bleed screw
- have helper press clutch to floor and HOLD IT THERE while you open then close the bleed screw
- helper pumps the clutch a few times HOLDS it to floor while you open then close the bleed.

Clutch pedal must be on the floor every time you open the slave bleeder. Lift the clutch pedal ONLY when the bleed screw is closed.

Will take 5 to 10 times.
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Old May 15th, 2018, 20:16   #5
spatuality
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Did this manual process for about an hour.

Did about 200 cycles, pulling the pedal off the floor each time. Wife was not impressed.

There's no hydrolic pressure at all. Just a spring click to the floor.

Any ideas about the gurgling noise in the video. Is that normal?

Last edited by spatuality; May 15th, 2018 at 21:15.
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Old May 16th, 2018, 04:27   #6
rallywagon
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OK So, you are showing a picture centered on the BRAKE master cylinder....have you inspected the CLUTCH master cylinder? Much smaller to the right of the brake booster. You might also inspect inside the car.
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Old May 16th, 2018, 11:54   #7
spatuality
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Yes, good catch.

I took pictures of the brake master cylinder because that was the only thing that looked like it could have something weird happening, at least from the outside.

The fluid gurgling noise echoed in a way that sounded like it came from a large container, like the brake master cylinder.

The noise seems to be coming more from the big brake cylinder than the clutch master. The clutch master doesnt seem to be making any noise, and it looks too small to be making an echoing fluid bubbling noise. But they are very close together, so I don't really know.

I did look at the clutch master cylinder, both on the engine side of the firewall and inside the car. I crawled into the drivers side footwell and felt all around, and looked at the clutch shaft, the carpet, and against the firewall as much as possible. There's no brake fluid at all.

Nothing on the engine side either. I have the battery out and have a good view of the firewall where the clutch master cylinder is. I'll get out and take a picture, but there's nothing really to see. No drips that I can see or feel, no puddles anywhere. The brake fluid reservoir hasn't changed that I can see.

Is there a test procedure for the brake booster, and the clutch master cylinder, that will help me know where the problem is?

Just thinking also, should the slave extend with some force? It has to be strong enough to push the clutch fork in. In the video, its pretty easy for me to push the slave in one hand.

Last edited by spatuality; May 16th, 2018 at 11:57.
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Old May 16th, 2018, 14:05   #8
spatuality
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Is the clutch hydrolic system connected to the brake booster in any way which would allow for fluid to move in the brake booster when the clutch is moved?
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Old May 16th, 2018, 16:26   #9
GCBUG00
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The slave cylinder does extend with force during normal operation. You should be able to compress the slave cylinder by hand w/o very much force. It will feel like a very light shock absorber.

The brake master cylinder and clutch master cylinder share a common reservoir. The connection for the clutch master cyl is much higher on the reservoir so in case of total clutch hydraulic system failure the brakes will still function.

When you compress the slave cylinder you should see a response in the reservoir, fluid movement or air bubbles.

Not sure how easy you can see the connection of the clutch master cyl push rod to the clutch pedal itself. It should be well connected, not loose and sloppy. If it's real loose it's not going to cycle the piston all the way back up. Worth checking.

Bleeding technique, not sure if you tried this one yet.

Pedal UP.
Open bleed screw.
Push pedal to floor.
Close bleed screw.
Lift pedal.
Repeat.

Pressure is not required to flush out a bubble.

Assumption is also that both cylinders are in working condition, undamaged etc.

Gary
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Old May 16th, 2018, 17:00   #10
rallywagon
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It sounds like you do not have plenty of brake fluid in the reservoir or the line from the reservoir over to the clutch master is blocked?
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Old May 17th, 2018, 09:41   #11
spatuality
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The resovoir level has been at just over half way between min and max. I added more to get it over the max line the other day, but there doesn't appear to be any leaking.

The line being blocked is a good idea. If I pull it, I'll probably break the seal and have to replace it, but at least I'll know what it is. I'll try that.


Quote:
Originally Posted by rallywagon View Post
It sounds like you do not have plenty of brake fluid in the reservoir or the line from the reservoir over to the clutch master is blocked?
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Old May 17th, 2018, 13:09   #12
spatuality
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I took the clutch master out. There's hard white bits that break apart like calcium deposits inside the lines going from the tank to the clutch master and from the master to the slave.

Now I guess to follow the trail backwards. Pull off the resovoir tank and see what's in there .

I haven't searched the forums on this yet. Is calcium inside the lines a thing?

Last edited by spatuality; May 17th, 2018 at 13:19.
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Old May 17th, 2018, 15:14   #13
spatuality
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I pulled the fluid resovoir and a large white flake fell out of the tank bottom. Same kind of calcium looking thing. It's perfectly flat, but breaks up easily when touched. Now to pull the brake master and see if I can flush out anything else in there.

How is the split tank setup internally? Im thinking if there's a valve between the front part and back part where the clutch pulls fluid from, it might of been blocked.
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Old May 17th, 2018, 22:14   #14
spatuality
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Whats with the floating metal disk with holes in it, in the master brake cylinder, forward hole?

Is it supposed to be like this?




Last edited by spatuality; May 17th, 2018 at 22:27.
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Old May 20th, 2018, 14:56   #15
spatuality
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Figured this out.

The pedal was still sticking to the floor after assembly. It spit out a bit of fluid, then just air.

I knew the brake fluid reservoir had to be at full for the clutch line to pull fluid, but that container needs to really be just shy of overflowing to get a couple clutch pedal pumps out of it.

Container filled right to the brim, no cap, bled the clutch and kept the resovoir filled. By the third bleed the pedal got firm, by 6 there were no bubbles, and I kept bleeding through 12 repetitions out of paranoia.

Last edited by spatuality; May 22nd, 2018 at 08:48.
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