87' 300SDL brakes
 

Hi folks I will appreciate your advice. My 300SDL sat for a couple of years. I have just replaced rusted fuel and brake lines and rear rebuilt calipers and one front rebuilt caliper with pads. I had pressure on the brake pedal before replacement. The front caliper I replaced first and bled it, it worked fine. Then I decided to replace rear calipers as they were frozen. Now I have no pedal pressure and no fluid drainig from bleeder valve on the rear right. I have car running and vacuum going to booster. What could be the problem? I have seen a similar post but this problem is not the same. I have also tried to search past posts and have not found anything relevant to my problem. Any direction to test procedures or advice will be appreciated. thankyou for your help

The $^@&* reservoir must be nearly overfull to get any brake fluid to flow from the "fill" port side (front brakes), over the "dam," to charge the rear brakes. You can only pump about two times before topping off.

Running the engine will not be of any benefit.

This is one of the reasons I am a convert to the power bleeding process. I built one out of a small garden sprayer, a few parts from the hardware store and an old reservoir cap that works like a charm. Just fill the reservoir with brake fluid, load the sprayer with same, attach reservoir cap then pump up to pressurize. Never have to worry about not having enough fluid in the rear section. This method does waste some brake fluid but for me is well worth it and makes it a 1 man job.

I would strongly recommend that ATF not be used in the brake system.

Wasting a little ATF is nothing compared to the damage ATF will do to brake system components.

Oops. Brain fart. Brake fluid of course!!!!!

Fixed..............

thanks for the responce. Is there a diagram or pictures for the power bleeding.

not sure what you mean. you simply attach the power bleeder tool to the reservoir top, in place of the original cap. then pump it up and bleed from each caliper. pretty straightforward.

I dont know what the power bleeder is. i have not seen it , but will make one tonight if shown.

ah, ok. i have an off the shelf one. motive. i haven't built my own, so i've got no advice on how to build one.

Motive Products #1 Selling DIY Brake Bleeder

a power bleeder is a pump up sprayer with a MC cap on the end... a pretty basic tool... it works wonderfully.

my brain fart.
 

Put in a new master cylinder,, and took 2 days of cussing trying to bleed the rear brakes,,,, untill my son came up and said there was not enough fluid in the BACK chamber to bleed the rear brakes,, fill the M/C to the top and bleed ,, 30 years of wrenching and I make such a dumb mistake,,,

i hear you brother, i hate these dual-chamber-single-cap reservoirs. dual circuits are a good safety feature, but they ought to have two separate caps then so you can access both reservoirs. both for evacuating the old fluid, and for filling with new. race cars have dual reservoirs with separate caps for this very reason. i guess adding a second .25 cent plastic cap is just too much for the bean counters, who these days, are given a louder voice than the engineers. :rolleyes:

brake fluid
 

Regarding using auto trans fluid in a brake system, it does work well in a low speed off road wood getting buggy. I have a 70 international truck that I used dextron for the fluid in. . no corrosion after sitting for a year or two. Hydraulic clutch also still works. Cessna planes use aircraft hyd. oil,not brake fluid. No corrosion there.
Temperature is the big thing. If the fluid gets hot enough to boil, the steam will pop a hose. After putting the brakes on.:confused:
The corrosion that brake fluid causes eats up the parts.
i wonder if on a non road going showcar hyd.oil might be the thing, with nothing corroding over the decades.
Road cars must use only proper fluids to be legal.

They also have seals and hoses that are compatible with Mil-H-5606A. (Said seals and hoses are not compatible with automotive brake fluid.) Any suggestion that hydraulic fluid and brake fluid are interchangable is completely assinine.