Help! I have no brake pedal, but no fluid leaks!

[Runamok81]

I have searched, and done some reading on the forums, and I now have enough information to be dangerous. I apologize in advance for posting another thread about brakes, brake fluid, master cylinders. But I would like some kind soul's help in diagnosing my issue. I believe I have a failed master cylinder, but I figured I'd ask the Vanagon gurus for their advice, before this newbie attempts the http://www.vanagonauts.com/Brake-master-cyclinder190.htm

I have an 85 automatic Westfalia. She sat for 2-3 months in the cold. I go to start her up, and before reversing out of the parking space, I depress the brake pedal, and it goes straight to the floor. No brake pedal resistance. There were no early warning signs. There were no puddles of brake fluid around the vehicle. I pulled the instrument cluster, and the brake fluid reservoir was empty. No fluid around the master cylinder. No fluid on the carpet.

I filled up the reservoir with Dot 3/Dot 4 Valvoline from my FLAPS. Without turning the car on, I pumped on the pedal. The brake fluid level will decrease a tiny amount, but then comes right back up. There is a slightly noticeable "click" in the pedal as it travels back up, about halfway.Again no leaking is evident. Pumped the pedal a good bit, with the car off. Then I pumped, with the car running. The brake pedal seems to have a tiny bit more resistance when the engine is idling, but resistance goes to nothing after the engine is cut off. As far as the vacuum system, depressing the pedal seems to increase the idle speed.

Most people, describe leaks of some sort when trying to diagnose brake issues. Are there anymore diagnostic tests I can run? To me, it just seems like the master cylinder won't take any fluid. Can the master cylinder just fail without any evidence of leaking? The master cylinder is old and rusted, looks like it has never been replaced.

Any alternatives to taking out the master cylinder?

[levi]

Yeah, the brake master can fail internally, but that doesn't mean for sure it's your problem.

Right now I'd suspect you just have air in the system.
You need to bleed all four corners, starting with right rear, then left rear, passenger, and then driver side.

By the way, you can bleed these pretty easily by yourself.

I use a clear hose that fits over the bleeder, that way you can see when air bubbles have stopped coming out, and when the fluid is coming out clear, also it keeps air from being pulled back into the system.

_________________
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[Runamok81]

Advice from Dad, suggests that their is a leak somewhere, hence the no fluid. And that my brake system is now air locked, so the master cylinder will not take any fluid. The next step is to go to the brakes and bleed out any air in the system. Whoohoo!

[Runamok81]

[?Waldo?]

Provided the pedal assembly itself is working properly, if there are no leaks present at the wheel cylinders, hydraulic lines or calipers, then the master cylinder IS at fault. If there is no visible leak and yet fluid is still disappearing, then the master is most likely leaking into the brake booster. I would start with bleeding the system, but if the fluid level continues to descend without any external leaks, the master is at fault. Although I don't share the opinion, the colloquial "wisdom" regarding clutch hydraulics here seems to be that you are asking for trouble if you replace just the clutch master or just the slave. there is no functional difference between the clutch and brake hydraulic components and so by that logic, if you replace brake master cylinder, you should also replace the rear wheel cylinders and both front calipers...
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I am a high-functioning autistic into VW diesels and Vanagons along with other things that are unrelated to this site.

[Runamok81]

[BoneStock67]

So, anything happening on this, Runamok?
I'm having similar symptoms ( http://www.thesamba.com/vw/forum/viewtopic.php?t=449239 ; Thanks, Dhaavers) and am also interested in this question of the master cylinder leaking into the brake booster. Is such a leak obvious once you get the master cylinder out?
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1986 Wolfsburg Westfalia Weekender 2.1L stock
1967 Beetle, now becoming my daily driver again, after a long rest in the garage

"There are two possible outcomes: if the result confirms the hypothesis, then you've made a measurement. If the result is contrary to the hypothesis, then you've made a discovery.” -Enrico Fermi

[camerahunter]

It could be the clutch mater cylinder leaking. Mine is and I am looking for help replacing that and found this question. Pump your clutch pedal and see if there are any drips from the master cylinder mounted to the front of the van at the sering column.

Thank you,

David
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1984 - Daily driver

[wolfej1]

I had issues as well. Went to back the van out and no brake pedal or clutch. Checked things out and found the clutch slave was leaking. Fixed that, bled the clutch and brakes and all seemed good.

However, last spring when I checked the fluid level, the same thing happened, but the fluid level in the master cylinder reservoir was not low enough where it sucked any air in so I just added some to bring it to level.

Then I started the van up, to let it idle and I noticed it was blowing white smoke when i revved it up good. I figure it had to be brake fluid that leaked from the master cylinder into the brake booster and was getting sucked into the engine.

Finally, I just checked my MC level today and it is indeed low again - it was at the top line when I parked it in November and now it is midway between both lines and the van has not been started or moved during this time.

Really blows because I put a new master cylinder and brake booster on 4 years ago.
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1982 Westy
2004 KDX200
2008 Kawasaki KLR 650
1979 Yamaha DT 175
1995 Toyota 4Runner

[Runamok81]