cannot get air out of breaks - PeachParts Mercedes-Benz Forum

#1 09-12-2006, 06:05 PM

hello, i am having a nightmare with these breaks i have bleed them about 10 times today, and i even got a hand vac. pump and still could not get all the air out of them, the car is a 56 219 and my question is are the dual wheel cylinders known to leak between each other? there are no visable leaks but air is still getting in some how, the master cylinder is new but i can't seem to get the air out of it either. some one please help.

t walgamuth · #2 09-12-2006, 07:22 PM

ok just in case there is any question, i will attempt to describe how to bleed brakes the old fashoned way.

i have never had much luck bleeding them with a minivac but lots of folks swear by them (i just swear at them).

first make sure your master res is full.

then starting at the furthest point from the master cyl. loosten the brake bleed screw and then tighten it back up. i will assume that all of yours are loose but just in case, if loostening them for the first time apply generous pb blaster and let it soak before attempting to loosten them. then begin by wiggling it back and forth til you are sure you can loosten it without breaking it.

have your partner pump up the pedal til he or she begins to get some firmness. then hold it while you loosten the bleeder. when the pedal reaches the floor (not too hard now) tighten the bleeder and have him pump it up again. repeat til you see no bubbles coming out. then move to the next closest bleeder to the mc and repeat til you have done them all.

to minimize mess attach a small clear plastic tube to the bleed nipple and run it into a jar.

check often to be sure the res is not dry.

good luck

tom w

#3 09-12-2006, 11:09 PM

yes i am familiar with that method of bleeding breaks. had wife pump breaks after I removed drums and found that right rear wheel cylinder is leaking, but with the drums on the leak didnt reach the ground therefore I didnt see it earlier. I am a truck driver so it will be two weeks from now when i become avliable to work on this project again.

t walgamuth · #4 09-12-2006, 11:55 PM

if you havent already it sounds like you should rebuild all of the hydraulics on it.

been there too.

sorry for assuming you didnt know how. but i figured the explanaiton might help someone out there if you didnt need it.

tom w

sokoloff · #5 09-13-2006, 10:04 AM

When bleeding the brakes on a ponton, you start with the two nipples on the booster, then right rear, left rear, right front, left front, booster again and finally master cylinder. But if you've got leaks, you've got other issues to correct. May need hoses too.

You ought to think about joining our ponton group too. See http://autos.groups.yahoo.com/group/ponton/

Len
'59 220S Cabriolet

300SDog · #6 09-13-2006, 09:42 PM

Yeah bleeding brakes is 2-man operation. You want to close the bleed nipple exactly when somebody pushes the pedal but not all the way to the floor. Tell the wife to time a 3 second pedal push and then shut the bleed nipple at count of two.

Otherwise working single-handed can recommend: http://www.speedbleeder.com/ with its own internal shut off valve.

#7 09-15-2006, 08:07 PM

Its has new hosees and i think that the rear cylinders are the only one with a leak, but after i get those fixed hopefully i wont have any more problems...

Thanks for the imput!

t walgamuth · #8 09-15-2006, 10:50 PM

if you are unlucky after rebuilding or replacing all the hydraulic parts, and you get the air out of the system you will find the rusty line when it pops and leaks.

at that point if you havent already i would replace all steel lines too. if you dont make sure your emergency brakes work since it is a single master cylinder.

i had the uncomfortable pleasure of driving my 6000# 51 caddy hearse home with just the emergency brakes after a failure that occurred under very mild braking. i can only imagine the panic if i had been under a panic stop situation and they failed!

good luck, sounds like an interesting project!

tom w

FloodKid · #9 09-17-2006, 03:43 PM

Im having this same problem.
While bench bleeding ive found that the front hole on the master cylinder didnt bleed with out pushing with alot of pressure (pressing really fast and really hard.) And when i bled the back brakes there was very little, if any, fluid coming out.

Does anyone know where i can find a diagram, or at least tell me which lines on the master cylinder go to which brakes.

300SDog · #10 09-17-2006, 08:05 PM

Actually for bleeding the system they recommend working from the LR callipre first, being furthest from the reservoir. But I generally prefer working from front callipres to start, figuring thats the easiest way to completely flush the reservoir with fresh DOT4 from the git go. And pumping hard and fast might not be such a good idea. Instead try smooth and steady into a jar that has brake fluid already in it to prevent pulling air back into the lines on the pedal backstroke.

And yeah it will take millions of pumps to clear out the rear brake lines. Figure about 1 quart comprises the entire system. Understanding MC brakes lines should be obvious by tracking the lines. And speed-bleeders made the job helluva lot easier for me - worth the $27.

#11 09-18-2006, 09:48 PM

On my car, the line coming from the center output on the master cylinder goes to the rear breaks. On the front breaks the oputput on the left goes to the left front wheel and the ouput on the right goes to the right wheel.

if that helps you at all let me know

Furious D · #12 09-18-2006, 10:52 PM

I don't have any specific info in the Ponton, but I did learn a valueable lesson bleeding the brakes on a Volvo 142E last year. We had new calipers, lines and fresh fluid in the system, but somehow could not get the air out. We tried many different methods, including one of those newfangled vacuum bleeders. It turned out that the master cylinder was pooched and was drawing air in as well. Needles to say, a fresh master cylinder cured the problem.

250 Coupe · #13 09-19-2006, 02:04 AM

I have the Eezibleed thingy from this guy. It works as advertised and I'd rather do it this way than have both the wife and the fifteen month old in the driver's seat at the same time.

I also have the Digital GasTester and it work well even though it only weighs two or three ounces.

Michael

Douglas Broome · #14 09-20-2006, 12:57 PM

On a Mercedes this age almost certainly the rubber flex hoses have swollen. They should be replaced ASAP. Easy DIY job except for the right front which requires a contortionist or two people. The key is to avoid snapping the steel lines at the nut where the hose connects to the fender. It is most likely corroded and "frozen." There is a technique for avoiding this. I have replaced these on both pontons I own. Hoses are not that expensive. Different ones right and left rear; identical front both sides. I have a new right rear one still in package that I am willing to sell from much below dealer price. douglas.broome@att.net

Douglas Broome · #15 09-20-2006, 01:03 PM

I used to use the Ezebleed device which worked fine. The bleeder by Motive Products is much superior. http://www.motiveproducts.com/02bleeders.html. I recommend it highly.