I have a 97 Ram 2500 that I had to change 2brake lines that were cracked. We bled the lines with the engine off, and the peddle is rock solid on the 3rd pump. When we start the engine, the peddle falls to the floor. We tried to bleed the lines with the engine running, and have the same effect. Changed the master cylinder, rebled the lines with engine off and running, still same effect. When the engine is running and you step the peddle all the way to the floor, the engine seems to pull down. I had the same effect when I took off the vaccume line and put my finger over the end of the hose.

Would anyone have any ideas for me to check to try to solve the problem? Thanks for any info.

 

are you bleeding the lines properly? ? its more than just stomp the pedal and let some air out.. heres a home made 'paint' diagram... bleed from the FARTHEST to the CLOSEST to the master cyl .. when you bleed.. start with bleeder valve closed... start engine.. have someone pump brakes 10 - 15 times then hold it.. you open the bleeder... do that until you get NO AIR coming out of the line.. then move on to the next.. do that on all 4 tires.. MAKE SURE YOU DONT RUN OUT OF FLUID IN THE MASTER CYL or you will just be doin it all over again..

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That could be one of the problems - We were going backwards. Front Drivers to Passengers to Rears. Will try it again tomorrow and post outcome - Thanks for the help.

 

to make things easier...you could also get a vacum bleeder. i just got one and it is nice. i got the cheap $30 one....but you pump it up, open the line, and it draws the air out of the lines. Just like mentioned above, but only requires one person.

 

After rebleeding the lines, it was still the same. With the engine off, we get a rock hard peddle with 1/2 a pump. Start engine, we loose it. We decided to change the booster and gained a little, but we still can't get breaks back to where they should be. After about 8-9 pumps, peddle finally starts to stiffen for a little bit. This one's got me stumped!! Any thoughts??

 

its your brake booster ...