Hello Everyone .....
Just got done a complete brake job on my 350sd.
New rotors , calipers, brake lines.
I bled the brakes and cannot get a firm pedal.???
I installed a new MC bled them again and still a very soft pedal.
Drove the car and it will only stop if you pump the pedal.
I am using a pressure bleeder.
??????
What am I doing wrong????




Please can someone help
-Anthony

You still have air in there somewhere. Did you start bleeding at the MC after the install?

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'72 Triumph T100R

Try getting the back wheels up in the air by putting the back of the car on jack-stands. Sometimes this helps air trapped in the lines to 'rise' towards the brake calipers where it can be bled off.

Start bleeding the Right Rear brake first, then Left Rear, Right Front and finally the Left Front. Furthest bleed screw first moving around to the nearest to the Master Cylinder.

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After installing a new m/c and before bleeding the wheels, you must first bleed the m/c to get all the air out of the m/c. Simply bleeding the wheels will not get the air out of the m/c. The same thing will happen if you let the m/c reservoir go empty and get air into the m/c. You can pump a gallon out of the wheels and the air is still trapped in the m/c and the pedal remains soft and the travel is too long.

Thank you guys for all the replies
Before installing the MC I did bench bleed it.
After install I pressure bled the MC lines and the ABS lines.
I then started at the pass rear and worked my way to the drivers front.
Some one suggested the "secret" hidden rear reservoir of the master cylinder.
This seem to be getting fluid. I’m using 20 lbs. of pressure. Is that enough?
The pressure bleeder keeps the fluid level up in the MC.
I even tried the two man ....errrr 1 woman, 1 man bleeding technique.
Dervman ....Yes I did jack up the back end higher than the front.
Is that ABS unit a problem?
I never had this on the 300SE and I did the same brake job.
????
Any other ideas?
Is it just a stubborn air lock?

You posted the same question on the tech forum and provided different information on the tech forum. Over there you indicated that the m/c was "slurping" clearly indicating that it had run out of brake fluid in one of the reservoirs.

As stated above, this will require you to bleed the m/c again. Just be careful not to run it out of fluid, in either reservoir, again. You must keep one of them completely full to allow the fluid to flow over the top and into the other one.

Yes Brian, That happened eairler in the day.
I have bled the MC again.
And went through the proceedure all over again.
I did put fluid in the Pressure bleeder to keep the fluid level up in the MC.
With the same results...????
Do you have any ideas?

How much fluid did you bleed from each of the rear wheels?

I would say about 60 ml A wheel.
I drained the fluid into a measuring cup to be consistent all the way around.
Didn't see any bubbles... Ill let it settle overnight and try again tomorrow.
Ill disconnect the lines on the master and bleed it with my helper. Then reconnect and bleed at the ABS and then to each wheel.
Dont know what else to do.....
???

Take the pressure bleeder off and fill the master cylinder by hand. All the way up to the lip of the fill neck -- this will fill the rear chamber. You cannot see it except at exactly the right angle from the front looking through the filler neck, it's way back there.

I'm not convinced a pressure bleeder will keep the rear full properly, the slot if fills through is pretty small.

I would also get a MitiVac and vacuum bleed the rear lines. The vaccum will expand the air bubbles rather than squashing them down like pressure bleeders do.

Also check to make sure the bleeder valve is on the TOP of each caliper as installed -- they fit very nicely on the wrong side of the car, just upside-down! You will bleed fluid until the end of time and never get the air out with the bleeder on the bottom.

Don't laugh, several people on the forum have done this, and the only reason I haven't is that I only take one off at a time, else I would get them backwards all the time!

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

60 ml on the rear wheels might be a bit low. I've been caught with a soft pedal before on certain American vehicles. I typically would bleed at least twice this amount, especially if I changed the master and possibly introduced some air at the top of the lines.

You can easily and quickly bleed with a hose stuck in a jar at each of the four wheels if you don't trust the pressure bleeder. Prevents having to close the bleeder screw for each upstroke of the pedal.

Peter Peter Peter Peter Peter Peter Peter Peter Peter Peter Peter Peter
Peter Peter Peter Peter Peter Peter Peter Peter Peter Peter Peter Peter
BLESS YOU MY SON!!!!!!!!!
Guess what I did???????


I have a MitiVac. But I think what i might do first is ahhh .....
Put the calipers on correctly.........
-- they fit very nicely on the wrong side of the car, just upside-down!
And they look nice too!!.............

As dyslexic as I am, I'd do this all the time if I ever took both off at the same time! Some days up from down is pretty difficult.

Glad this was easy to fix!

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Well, at least you can now use that pressure bleeder without losing confidence in it. Just make sure the rear reservoir stays full. When I bleed the SD with the easibleed, I have to take it off the m/c several times and add fluid to be sure I don't run it dry.

Been there, done that!!! LOL
If you work, you make mistakes , hmmm , the reverse is true too.

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