New callipers, No brekes now. Grrrr - PeachParts Mercedes-Benz Forum

Stevo · #1 08-14-2003, 08:06 PM

I am having a problem figuring this one out, ("79" 240D) Had a rear calliper that was dragging so I installed new ATEs, hoses & pads on the rears as they had not been done in a long time. I bled the system with the Speedie bleeder as usual but could get NO bakes, not "mushy" just all the way down. I bled them several more times,(all 4) still no workie so I figure master cylinder so I pull the one off the parts car, stick it on, same thing. Grrrrrr They feel normal if I keep the pressure bleeder hooked up tho, but as soon as I take the pressure off, right to the floor. The other master cylinder made NO difference at all. Of course both master cylinders could be bad, but like I said its the SAME with either M/S. I do seem to get air out of the rears every time I try the brakes and go back a bleed them. I must be missing something here. Any Ideas??

sokoloff · #2 08-14-2003, 09:14 PM

There are two compartments in your brake fluid reservoir. The front one has to be totally full for any fluid to flow to the back one. Are they both full?

Len

jbaj007 · #3 08-14-2003, 09:41 PM

Bleed nipple at the top, (right and left not swapped)?

Stevo · #4 08-14-2003, 10:35 PM

Ya..both sides of the fluid reservoir are full.

"Bleed nipple at the top, (right and left not swapped)?" Roger, roger, Bleed nipple on top of both.

I was thinking that after a cold beer and hot shower I would think of some explanition, maybe another beer will help

Steve

psfred · #5 08-15-2003, 12:46 AM

Try gravity bleeding so you can watch the fluid coming out to verify no air.

Sounds like you still have air in there somewhere, but that is a fairly simple system, not like it has a complex proportioning valve or anything for air to "hide" in.

I do know when we fixed the brakes on my brother's Chevy 1-ton, it took FOREVER to get all the air out of the front brakes. Worked lots better when we did, though....

Peter

Stevo · #6 08-15-2003, 11:32 AM

Peter

"Try gravity bleeding so you can watch the fluid coming out to verify no air."

I took the callipers off and had to wait a couple of days for the replacements and so quite allot of juice ran out but I pumped quite a bit through the system when bleeding. There must still be air in there. How do you "gravity" bleed ? I had my wife mash the brake and I could not turn the hub so there is something there which is a good sign I guess.

Thanks ...Steve

psfred · #7 08-15-2003, 07:08 PM

Steve:

Fill master cylinder leaving cap off. Slip some clear plastic line over the bleeder and direct it into a container, perferably clear so you can see what's coming out, and open the bleeder. Gravity will slowly pull the brake fluid down the lines and out the bleeder. It will go faster when the fluid fills or partly fills the plastic hose.

If the pads are gripping the rotor, you just have some air in there.

Make sure the fluid level stays up in the master cylinder or you can be at this a while....

If your wife will help, you can also bleed them the oldfashioned way -- have her step on the pedal, open the bleeder valve and let whatever is in there out, then close the bleeder valve when she tells you the pedal is all the way down. Have her slowly lift her foot off the pedal (if she goes too fast, you can suck air around the seals in teh master cylinder), then repeat until no more air comes out. Clear plastic tubing on the bleeder nipple makes this easier to see, and keeps the brake fluid off the tires and floor, too.

Pedal will get nice a hard when the air is gone on both sides.

Peter

Kyle Blackmore · #8 08-15-2003, 08:38 PM

Hi Steve , does the M/C need to be bench bled before installing , if all the fluid drained out of the reservoir then perhaps this is the problem . Good luck . Yea!!!! 500 posts

leathermang · #9 08-15-2003, 09:40 PM

Kyle just beat me to this one... I have seen master cylinders that HAD to be bench bled. Seems like you put it into a vise with soft jaws and put in fluid and hold your finger over the exit holes... and push on the piston... then get some plugs put into the exit holes and try to get it on the car without losing too much fluid... I did not believe the instructions when they said do this... but I was young at the time...

Stevo · #10 08-15-2003, 10:05 PM

jbaj007

You hit the nail on the head. I had some post holes to drill for a neighbor and when I got back to the brake problem this afternoon the bleed fittings WERE on the bottom when I checked . Thanks all for your help. Didn,t take long to swap them around and I am on the road again. I should have noticed the differance between the fronts (nipple on top) and the rears.

Steve