Spongy brakes (Jetta)

Welcome to the Mercedes 190 forum

Welcome to the Mercedes 190 owners forum, the place to be for all owners and lovers of the Mercedes 190E, 190 and 190D cars. Including Cosworth (2.3 16v and 2.5 16v), EVO 1 and EVO 2 models. Modified and concourse, track cars and daily drivers, all are welcome.

This free UK based club was started back in November 2005 to serve the w201 community and now has over 4000 members from all around the world and 340,000 + posts.

The members welcome you and encourage you to stay a while and have a look around. We offer you friendly chat and access to some very useful information as well as tutorials with photos and videos for many common repair and maintenance jobs. Whatever your needs there is a good chance you will be able to find what your looking for. Such as our Mercedes 190 buyers guide

Sign up to gain access to all areas including for sale / classified areas and country wide meetings and events. Many forum features and sections are only available once you sign up.

Join our us at mercedes190.co.uk!

If you're already a member please log in to your account:

Spongy brakes (Jetta)
Topic Started: Sat May 23, 2009 2:01 pm (136 Views)
Conrad	Sat May 23, 2009 2:01 pm Post #1
Gunman of the apocalypse Posts: 5,388 Group: Members Member #34 Joined: November 11, 2005	I'm trying to sort out the brakes on my Jetta Mk2 - I know it ain't no 190 but brakes are the same the world over. The brakes on this car are pretty much non existent at the moment. The pedal doesn't run away like a bad master cylinder would indicate, but you have to push the pedal almost to the floor to get a response. I unbolted the master cylinder to see if it was leaking into the booster, and it let out a big sigh. Is this normal? I bolted it back on and the brakes were back to how they're meant to be, but after a small amount of use went down again. What does this mean? Thank you, good night, much love.



Richy190E	Sat May 23, 2009 2:54 pm Post #2
Sales Rep Posts: 1,832 Group: Members Member #1,387 Joined: June 9, 2007	it could be either the vacuum supply pipe to the servo is perrished or cracked or the diafragm is split. If its a diesel it could be the vacuum pump.



Conrad	Sat May 23, 2009 2:57 pm Post #3
Gunman of the apocalypse Posts: 5,388 Group: Members Member #34 Joined: November 11, 2005	It's a petrol. Is there any way to test the diaphragm or that hose? Thanks!



Richy190E	Sat May 23, 2009 3:00 pm Post #4
Sales Rep Posts: 1,832 Group: Members Member #1,387 Joined: June 9, 2007	If you disconnect the hose at the manifold and suck on it, put your tongue over the end and allow it to hold a vacuum....if the vacuum dies off then there is your problem.



Conrad	Sat May 23, 2009 3:16 pm Post #5
Gunman of the apocalypse Posts: 5,388 Group: Members Member #34 Joined: November 11, 2005	I think I've found it. On the vacuum hose, there's a connector that connects the hose in the middle. This has two little towers on it, one has snapped off, opening it. I'm going to plug it and see.



Conrad	Sat May 23, 2009 3:27 pm Post #6
Gunman of the apocalypse Posts: 5,388 Group: Members Member #34 Joined: November 11, 2005	Nope, didn't change a thing. I'm going to bleed them.



Richy190E	Sat May 23, 2009 4:11 pm Post #7
Sales Rep Posts: 1,832 Group: Members Member #1,387 Joined: June 9, 2007	bleeding may be a good idea.



Conrad	Sat May 23, 2009 5:16 pm Post #8
Gunman of the apocalypse Posts: 5,388 Group: Members Member #34 Joined: November 11, 2005	The plot thickens. The moment I bleed one (any one), the pedal goes right up and is nice and tight. Turn on the engine and the pedal hits the deck again.



Richy190E	Sat May 23, 2009 5:37 pm Post #9
Sales Rep Posts: 1,832 Group: Members Member #1,387 Joined: June 9, 2007	hmmm, booster perhaps?



Conrad	Sat May 23, 2009 7:24 pm Post #10
Gunman of the apocalypse Posts: 5,388 Group: Members Member #34 Joined: November 11, 2005	Well I bled the crap out of it and that seems to have made the difference! I did get two big air bubbles, so fairly sure it was them. Thanks for the help, Rich.



Richy190E	Sat May 23, 2009 7:53 pm Post #11
Sales Rep Posts: 1,832 Group: Members Member #1,387 Joined: June 9, 2007	I hate brake systems sometimes lol. as long as you got some air out then thats a good thing.



Conrad	Sat Jul 4, 2009 5:34 pm Post #12
Gunman of the apocalypse Posts: 5,388 Group: Members Member #34 Joined: November 11, 2005	Well that never fully solved the problem, they were still crap. I replaced the master cylinder and now I have no pressure at the pedal at all. The new master cylinder is from a junkyard, so there is always the chance it could be faulty.



Conrad	Sat Jul 4, 2009 5:35 pm Post #13
Gunman of the apocalypse Posts: 5,388 Group: Members Member #34 Joined: November 11, 2005	Things have turned upside down. The rear wheel with an intact bleed nipple still has zero fluid to it. I cracked the pipe and the pipe is empty. The rear with a broken nipple is fine. The cylinder moves a little when the pedal is pushed and the line dripped when I undid it half a turn. The pedal has zero pressure. It went up a bit, but as soon as the engine was turned on it just dropped like a stone. Now it won't build up again. I undid the line of the wheel that has no fluid in it at the master cylinder end, and pressed the brake pedal. A shot of fluid came out, so the cylinder isn't at fault. I found the brake compensator, I want to undo the line to the wheel with no fluid in order to see where it's stopping, but can't get the lines undone. I don't really care about not having rear brakes, but having some brakes would be very nice! Why is there 0 pressure, the front calipers have no air in them? Surely I should get something in the pedal? Could the new master cylinder be dead, regardless of what it looks like from the outside? Or is the booster gone? Any other ideas? I just want pressure in the pedal! The car doesn't go on the road, by the way. It's a farm vehicle.



Conrad	Sat Jul 4, 2009 5:42 pm Post #14
Gunman of the apocalypse Posts: 5,388 Group: Members Member #34 Joined: November 11, 2005	Interesting development though, I was just pressing the pedal and noticed a hissing from behind the pedal itself. So I released it slowly, and there's a point right near the bottom where if you hold it, it hisses like air escaping or being drawn it. When you hold it at that point, it stalls the engine. Could this all lead down to a vacuum line being off?



Stempies	Sat Jul 4, 2009 5:51 pm Post #15
Hot Lips Posts: 3,305 Group: Members Member #2,380 Joined: March 6, 2008	Sounds like master cyl has gone or split in vacuum pipe, if you can hear hissing (where is master cyl on a jetta?). Who needs brakes on a farm??? Handbrake is much more fun!!!!!



Conrad	Sat Jul 4, 2009 5:59 pm Post #16
Gunman of the apocalypse Posts: 5,388 Group: Members Member #34 Joined: November 11, 2005	The vacuum pipe to the booster is fine, I blowing and sucking and it's not leaking.



Conrad	Sat Jul 4, 2009 6:11 pm Post #17
Gunman of the apocalypse Posts: 5,388 Group: Members Member #34 Joined: November 11, 2005	Right! I got my dad to sit on the back of the car, and instead of using a one man bleeding kit, did it the old way with my mum pushing the pedal and me opening and closing the nipple. It now works fine, fluid is coming out of the rear line. When the fluid started coming out, the pedal firmed up. But, as soon as the engine was started it lost all pressure again.



Rich27	Sat Jul 4, 2009 6:12 pm Post #18
If it has tits or an engine it will be trouble Posts: 13,272 Group: Members Member #348 Joined: June 15, 2006	Are the brakes servo assisted?



Conrad	Sat Jul 4, 2009 6:20 pm Post #19
Gunman of the apocalypse Posts: 5,388 Group: Members Member #34 Joined: November 11, 2005	I believe so, yes.



Rich27	Sat Jul 4, 2009 6:35 pm Post #20
If it has tits or an engine it will be trouble Posts: 13,272 Group: Members Member #348 Joined: June 15, 2006	Try taking the fuse out for the brake servo and start the engine, do the brakes still go spongey?



Conrad	Sat Jul 4, 2009 6:47 pm Post #21
Gunman of the apocalypse Posts: 5,388 Group: Members Member #34 Joined: November 11, 2005	Does exactly the same thing. If I turn the engine off, the brakes get hard. Turn the ignition one notch, the pedal sinks very slightly - normal. Turn the engine on completely and it drops to the floor. So by this I deduce a vacuum link at the servo? Edited by Conrad, Sat Jul 4, 2009 6:50 pm.



Conrad	Sat Jul 4, 2009 7:00 pm Post #22
Gunman of the apocalypse Posts: 5,388 Group: Members Member #34 Joined: November 11, 2005	If I pull off the hose at the servo end, the pedal remains rock solid with the engine on. The idle goes crazy, but the brakes stay firm! So is it fair to say the hose is shot?



Rich27	Sat Jul 4, 2009 7:30 pm Post #23
If it has tits or an engine it will be trouble Posts: 13,272 Group: Members Member #348 Joined: June 15, 2006	Conrad Sat Jul 4, 2009 7:00 pm So is it fair to say the hose is shot? Yup.



1 user reading this topic (1 Guest and 0 Anonymous)


« Previous Topic · Brakes · Next Topic »