The other day I decided to change my rear brake pads and attempted to do the whole bleeding thing with the help of a friend and a mighty vac....I watched several "how to" videos on youtube, read through the forum, and even the mighty vac had instructions on how to bleed brakes....long story short, I now depress my brake pedal and nothing happens, the car won't stop until the pedal is all the way to the floor! Me and my friend investigated everything, we rebled the system, and still a no go. Here are a few things that may help you all to help me:

1) Both rear calipers were depressed in order to put the pads on; They were still depressed when I rechecked everything. I'm guessing they are the oigninals.

2) Reservoir was drained and master cylinder was taken off for inspection. There are two ports with grommets in them, the port closet to the firewall was filled with DOT 4 fluid and so was the other port, but the one closet to the firewall did not expell the brake fluid like the other one after I blew in it.

3) When rebleeding the system, there was little to no fluid coming out of the rear driver side bleeder, even with a full reservoir and me applying pressure.

PLEASE HELP. Thanks.

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1990 190E 3.0L

if you fooled with the master cylinder, you have to bleed it first.

whenever you bleed a caliper, it isn't ready until you get a solid stream of brake fluid. close the bleed nipple while fluid is still coming out (under vacuum from the mity vac, or under pressure from the brake pedal).

after bleeding the mc i would use the brake pedal and pal approach to bleed the lines, since it sounds like they are empty. it's easier to push fluid with the mc pistons than to pull it with the vacuum.

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Prost!

Yes, google "bench bleed" and "master cylinder." You'll have to do that as your first step. At least, that's where I'd start.

EDIT: Have you got ABS? Getting air into the ABS pump can be a headache, so be careful. You may just want to turn this project over to a pro if that's the case.

The moral of the story: never, ever let the master cylinder run out of fluid if you can help it.

will make your job a hell of a lot easier. The MityVac is a vacuum bleeder and will allow air to be pulled into the system around the bleed screw threads.

I use a Motive Products pressure bleeder available from many sources for about $45. It is foolproof and automatically ensures your master cylinder remains fully topped off. Makes it an easy one-man job.

I've never had an issue with using a MityVac, but one thing I need to ask:
Did you bleed the front brakes?

As you removed the MC, all 4 wheels need to be bled. You may use a full quart of brake fluid to do it right if you have ABS. Bleeding my Charger's brakes when I took the calipers off for paint was a PITA, I got tiny bubbles for about 10 mins from each wheel.

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I go along with the power bleeder advice but what concerns me the most is the "little to no fluid coming out of the rear driver side bleeder" I think you need to make sure that there is a steady flow of fluid coming out of that. It should be the same as the other rear caliper.

My guess is that if there is restricted flow there is a problem with either the caliper or the flexible hose. If I were you I'd change the flexible hose first!

Good luck

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Vacuum bleeding does not work with ABS.
Need to pressure bleed.

Also, now that you've run the pedal to the floor on a used master cylinder, you have likely damaged the master cylinder seals......

Jim

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I have bled the brakes to spec or the way that everyone is saying, minus a pressure bleeder, the issue is that only after I noticed the pedal sinking did I go and start taking things apart. There is little to no fluid coming out of the rear driver side bleeder, even after applying pressure for 15 to 20 minutes. Even if there is air in the line shouldn't I still get some fluid out? Looks like the majority of you don't think there is any mechanical problem, so I think I'll just go try to start over with the bleeding. this is my first time doing this job.....its a pain in the @$$

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1990 190E 3.0L

Indeed that is why I think you've either got a collapsed flexible hose or some blockage in the caliper. Have you actually unscrewed the bleed nipple from the caliper where little oil comes out? Is it clean? Can you blow through it?

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

I was assembling the pads wrong. There was a T-shaped metal spacer that goes between the pads that I failed to put on correctly. Thanks for all your input everyone.

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1990 190E 3.0L

That's good - but as stated above - Mity Vac not suited for ABS systems. Pressure bleed the system.

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Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"

yeah, I invest in one next time, but the mity vac did do a pretty good job, would've been perfect had I not put the spacer on incorrectly. next up is to seafoam the car again.

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1990 190E 3.0L

I don't know how a misplaced spacer (anti-rattle spring?) could produce a soft brake pedal. It's hard to tell exactly what's going on without being there, but I'd be concerned that there's still a problem lurking.

I don't want to come off as a mity-vac expert or proponent, but I don't think this claim is correct. I have used the mity vac numerous times on ABS-equipped cars. The only issue I see with the method, as they point out on their own website, is that you can draw in some (very) tiny bubbles around the bleed screw threads. This is addressed by using teflon tape around the threads or by using the pedal-pal method for the final bleed, although I've never noticed the bubbles to impact pedal feel much anyway.
Maybe there were some early ABS systems that it didn't work on. Any additional info?

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Prost!

I highly doubt that this was the source of your problem, as I can't think of a way that it would change the pressure of the pedal and pedal feel. More likely after changing the clip you were able to get some air bubbles or a blockage out of the system. I would be verrrrry careful

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TC
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