Brake Job Help

Hi All,

I have a brake job that is turning into a real piece of work. On a road trip, I lost brake pressure. I was able to stop the vehicle, but the brake power was limited and the pedal would drop all the way to the floor.

I ordered a Meyle brake master cylinder and new hoses. None of the hoses would come loose even with a brake line wrench. I was able to replace them with vice grips and a torch. The existing system was disgusting. Everything was filled with black dirt and brake fluid. One of the hoses had the rubber outside layer broken off and another was partially blocked on the inside.

I believe I have everything connected properly and am trying to bleed the system. On a few of the brake calipers, I am not able to get any fluid to come out and there is no pressure. I tried bleeding with a helper. After doing this for quite a while with no results, I ordered a power bleeder. Are there any other suggestions for getting this to work?

I also noticed my rear passenger caliper is missing both of it's bolts. I had a mechanic replace that last year. Where can I buy replacement bolts?

h.ubk

I did some poking around in the back and it looks like I have a proportioning valve. I suppose I will check that for pressure before I play with the lines. That will be a great project for Monday.

h.ubk

Those bolts are probably missing because the previous mechanic stripped the threads in the caliper carrier. May want to check that before buying bolts.

so..... you did a road trip with a poorly maintained car? is this a new car to you and your driving it home? if i was you, i would replace all the brake lines, ALL OF THEM, and the brake hoses to calipers, get a seal and boot kit and all the slide pins and boots, pads, rotors, and full rear kit, portioning valve can probably be rebuilt, bearings, and drums for the rear, you already have a new master, rebuild the front calipers, and get new rear slaves and plan on a new clutch slave. redo the entire system.get a flare tool and copper lines.
a system that old and THAT neglected will have TONS of pitting and issues for years to come with old lines that have been that poorly maintained. i would not trust 1 component on that system, NOT ONE.
I know this sucks but you really trust your life and willing to put the lives of others on the road with a system that has probably not been bled in probably 20 years? PLEASE for the sake of others, just redo the entire system. i know the lines are a PITA but i bet there shot and its just a matter of time when they fail due to newly established proper working pressures.
my chevy van was 25 years old when i got it and the brake fluid was BLACK like oil and almost as thick! it took me about a gallon of brake fluid to flush it out over the course of 4 years, a flush every 1,000 miles and it was still chucking out black bits of crap even after that then BAM, brake line exploded. i cut it in half down the middle and there was pitting throughout the entire line from the inside. thank god it blew in a parking lot!

again i would not trust any component that has that fluid in it.

for now, to limp it home, flush the crap out of it and keep your distance.

so..... you did a road trip with a poorly maintained car? is this a new car to you and your driving it home? if i was you, i would replace all the brake lines, ALL OF THEM, and the brake hoses to calipers, get a seal and boot kit and all the slide pins and boots, pads, rotors, and full rear kit, portioning valve can probably be rebuilt, bearings, and drums for the rear, you already have a new master, rebuild the front calipers, and get new rear slaves and plan on a new clutch slave. redo the entire system.get a flare tool and copper lines.

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I have done a lot of work on the car, but I really have no idea what the history is on the brake system.

I'm not going to replace the hard brake lines unless it is really needed. If it seals and holds pressure, then I am happy with it. I think you're going a little overboard with your list here. I have no way of knowing what internal damage there is on the inside parts of the lines on a 23 year old car. Rotors should be replaced when they are out of spec based on mics, not just because the whole thing is old. Likewise, it's anyone's guess how old the front calipers are and when they are going to fail. The rear brakes are disc as well.

This is not a car I am going to professionally restore. I am just looking for information on getting the system to bleed. It's very possible that this whole problem is due to the proportioning valve failing and not anything else.

h.ubk

h.ubk,
Just curious, how's your MKIII faring what with Idaho+snow+salt?

h.ubk said:

I really have no idea what the history is on the brake system.

I'm not going to replace the hard brake lines unless it is really needed. I have no way of knowing what internal damage there is on the inside parts of the lines on a 23 year old car.

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Here's the issue for real with those statements. Brake fluid is hydroscopic, which means it absorbs water. The issue he was saying there's likely to be when you have a neglected brakes system is pitting due to corrosion. That weakens the brake lines due to pitting and you're print yourself at risk of failure again beings you just had a failure. Did it not scare the crap out of you?

I agree he was a bit dramatic and it sounds like a lot of work.
You're right about the discs and the calipers are the first to see the issues due to water in the lines.
Just remember your brakes have been neglected and that's obvious due to black fluid in the lines.

Sent from my moto g(7) power using Tapatalk

Bleeding a system with no abs should be as easy as a long small hose a wrench, and a can to catch it in. Other than you know, fluid and such.
The fact that you cant get fluid to pass through means you have a blockage. What is it blocked with? Metal oxide from the water in your brakes. Rust from the master and mostly your brake lines. If you take a better look at the black debris it's actually dark green, like really dark. That's because your brake lines are copper.
Even if your lines are in a shape that a competent mechanic would call safe for off road use! Your going to trash it trying to take apart the portioning valve. Those things are notorious for bad days.
Soak the piss out of it with atf and acetone 1:1 mix for days!and give it a red hot heat to the threads and let it cool down slowly, then try and warm it up and remove.

It's actually not as big of a task as you think to replace brake lines.
Take one off, bend new pipe to match, install! One at a time.


Now, was the fluid black or was the fluid clear with some black bits in it?
I reread your post and it's not clear to me the condition of the fluid. I assumed it was back fluid but you say it had black debris in it. So..... maybe your ok?

Just curious, how's your MKIII faring what with Idaho+snow+salt?

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Usually, it just sits in storage during the winter and then I drive it in the spring/summer. I did drive it a bit last December. It didn't seem to like to start cold in 9 deg F weather, but otherwise did ok.

h.ubk

Here's the issue for real with those statements. Brake fluid is hydroscopic, which means it absorbs water. The issue he was saying there's likely to be when you have a neglected brakes system is pitting due to corrosion. That weakens the brake lines due to pitting and you're print yourself at risk of failure again beings you just had a failure. Did it not scare the crap out of you?

I agree he was a bit dramatic and it sounds like a lot of work.

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I know. I totally get it. I'm not scared, I'll just work through it. I may end up bleeding the brakes again after I get this settled just to get the lines a bit cleaner.

I'm not going to put too much into this because eventually the engine is going to get pulled to go into a 4x4. But, for right now, I want to make the brakes as safe as reasonably possible. I'm just not going to pre-emptively replace anything because that could go on forever with this car.

h.ubk

Nit-pick of the day:

eddieleephd said:

...Brake fluid is hydroscopic, which means it absorbs water. ...

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The correct term is hygroscopic.

Yeah, I know, it sounds crazy, but a hydroscope is a device for looking at things underwater, an example of which would be a swim mask.

Cheers,

PH

h.ubk said:

........................snip...................... The existing system was disgusting. Everything was filled with black dirt and brake fluid. One of the hoses had the rubber outside layer broken off and another was partially blocked on the inside........................snip......................

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So you've replaced/cleaned a couple hoses. What do you think the rest of it looks like inside? I'd be replacing most of the components cause it's brakes. But at the least open it up, run some cleaning fluid thru the lines and calipers, reassemble then bleed. 2 big bottles, like a liter per wheel.

I checked the previous owner's maintenance records and apparently the whole system was flushed 10 years ago ... not great, but I'll bet there are a bunch of cars driving around that are worse.

There was some dirt in the lines, but I think I can get it reasonably clean by bleeding it thoroughly and then again in a few weeks after driving it a bit.

h.ubk

Well, the fun continues. I installed the proportioning valve today and was able to bleed three of the calipers with my new power bleeder.

I could not get any volume of fluid coming out of the front driver's side caliper. I tried cracking the line at the master cylinder and fluid was coming out and then was able to get fluid to come out on the hard line and the new rubber line I replaced, but it was absolutely bone dry on the bleeder screw.

So, it looks like I'm getting new front calipers. Anyone have any recommendations? I am leaning towards just a cheap brand from AutoZone or O'Reilys just because they have local warranties.

h.ubk

jhust order a set of seals and boots for your calipers. compressed air will push the piston out, some 320 grit on the piston, clean it all up and lube with brake fluid when installing seals, it helps to have a 3rd hand to install the piston over the boot. ive done hundreds of these, takes about 30 minutes with cleaning them if you are not quick like i am or have a ultrasonic cleaner like i do. cost is about 10 bucks.
i have had PLENTY of reman calipers have sand in the piston causing them to seize up when in use. if that does happen, just pull the caliper apart and clean it up and reassemble.
i would highly suggest silicone high temp grease for the slide pins.
i hate and don't trust remans.

Have you tried just removing the bleed screw all together? might be as simple as replacing the bleeder screw.
I would remove the rubber brake line from the caliper and the bleed screw and try and blow it free while still on the car and on the rotor.

Yes, I have removed the bleed screw altogether while pushing out 15psi with the power bleeder. Nothing comes out of the caliper.

I would remove the rubber brake line from the caliper and the bleed screw and try and blow it free while still on the car and on the rotor.

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That's a good idea. I may try that tomorrow. I'm not familiar with VW calipers so I don't know how they are constructed inside. What you are saying may work if there is dirt blocking a passage, but probably not if something internally is seized by rust.

h.ubk

h.ubk said:

Yes, I have removed the bleed screw altogether while pushing out 15psi with the power bleeder. Nothing comes out of the caliper.



That's a good idea. I may try that tomorrow. I'm not familiar with VW calipers so I don't know how they are constructed inside. What you are saying may work if there is dirt blocking a passage, but probably not if something internally is seized by rust.

h.ubk

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It takes about 10 seconds to pop the piston out of the caliper with a block of wood and some compressed air. You will easily be able to tell what's going on. It's just 2 seals and a boot. It's really easy to do.
I'm fairly sure the issue is right at the bleed screw mating surface.

Ok, I was able to get the front caliper to bleed by blowing it out with compressed air -- a lot of fluid and dirt came out and after that, it was just fluid coming out from the bleeder screw.

The caliper that was just dangling was not providing any braking action -- I could rotate the wheel while a helper pressed the brake pedal. I was able to put some bolts on the rear caliper from a front brake pad kit I had and now all calipers are braking and all are bled thoroughly with the power bleeding system.

So, now while driving the car, the brake pedal feels a little hard and has started squeaking a bit since I put the new master cylinder in. I pulled the vacuum line going to the brake booster and it is getting vacuum -- I didn't put it on a gauge, but just held it up to my finger to feel it. I also tried driving around with the booster vacuum line disconnected and it felt like it braked a little faster, although I had to push harder on the pedal.

Are there any other checks I should do before concluding I have a bad booster?

h.ubk

Measure how much vacuum you have first. Boosters dont usually fail as often as you think.
Did you deglaze the rotors for the new pads? Make sure you do.
Also bleed the clutch if it's a manual. They are part of the same system. I'm assuming yours is auto so.....

I'll measure vacuum on Monday.

There are no new pads on the car yet.

The car is an manual and the clutch is performing exactly as it should.

Regarding the booster, the car has about 380K miles and I believe the booster is likely original.

h.ubk

Ok. Just so you know, here is how to remove it. Dont bother with all the other DIY guides, they all failed me so I made a video on how to remove it. If you think you need a booster, you can have mine. I pulled it from my car when I scrapped it. Works fine.
Anyways here's the video
https://youtu.be/nu_1VdXXK3k


Chances are your vacuum pump is leaking. It's a common issue with them. Easy to fix, vs a booster. It's basically the only thing that runs off it. So it's probably leaking. My Jetta had 360k on the clock and booster is fine. But I had vacuum pump issues with it leaking.
Food for thought.

You might be interested in my brake set up. You can buy it from me. Drilled dortors, rebuilt calipers new pads, hawks HPS. Has about 1,000 miles on them.

Well, the issue appears to be mostly fixed. I tested vacuum and was getting just under 15 in-HG. I'm not sure what the number should be, but I saw another thread showing 29 in-HG. I tracked a vacuum line connected to the pump and then a tee connection. One of the lines was going to the passenger side and connected to nothing. I then plugged the line and retested at about 25 in-HG. Right now, the brakes are stopping mostly as they should. The pedal feels a little bit off (not sure exactly how to explain), but the braking power is where it needs to be and I do have power assist.

h.ubk

If you pump the brakes quite a few times and then hold it down, does it slowly goes down or get soft?

If I pump a few times and then hold it down, it seems to hold in place.

h.ubk

h.ubk said:

If I pump a few times and then hold it down, it seems to hold in place.

h.ubk

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Then your master and booster are working perfectly.
I would swap pads and deglaze rotors or even possibly just sand down the rotors a bit and go bed in the pads.
Sounds like you got it working well tough. Maybe you need to work on the portioning valve? Only things I can think of that would cause braking to suffer at this point.

On my wife"s A3 from Texas with my Power Motive at 10 psi nothing came out, so I pressed down on the brake pedal and bunch of black liquid came out and after a bit nice clean fluid.

reminder that when bleeding old fluid, put a block or 2x4 or a brick behind the brake pedal . pushing the pedal down past its normal travel ends up killing the master as it puts crud into the seals that it never usually sees.