Hi all , i ve been suffering from brake on my ram since two month and no solution , changed brake pads (original ) and discs (ventilated) , changed the servo and the pump two times (used) no vacuum or oil leak , what happens is in the morning when first start i have no brake till i drive and step on brake paddle 3 to 5 times then the brake is normal (only the front wheels) back wheels dont know any thing about me stepping on the peddle but the car stops firmly and this is ok until i park the truck for an hour or more,and when i want to drive again i have to do the same thing to get the brake working and only the front wheels as i mentioned , i took it to dealer and every dodge mechanic in here and all say they dont know why its doing this !!! Any help plz

 

Did this happen out of no where? Did it slowly get worse? I am guessing they have been well bleed?

 

Yes all of the sudden , and bleed more than 5 times no air nothing

 

if you're driving on the highway and you don't hit the brakes, do you lose them until you pump the pedal?

If so then I'd check the wheel bearings in the front, as they might be badly worn causing the brake rotor to tilt into the caliper and thus compressing your caliper, which would make your brake pedal go to the floor if you step on it.

To check them yourself, get the front wheels off of the ground (with E-Brake engaged and back wheels blocked). Once they are off the ground grab the top and bottom of the tire/wheel and try to shake it in and out (bottom in & top out then top out & bottom in), if it moves at all, you likely have a bad wheel bearing.

If both wheels check out, then there may be something wrong with the master cylinder under braking (maybe firewall is flexing?)....

 

some times yes i lose brake till i pump peddle but not always , checked wheel bearing all good , what do u mean by firewall flexing ?

 

I would think he would feel the pulsing, no? I had this same problem on my race bike (zx6r), but I would also notice a pulsing from the warped/bent rotor.

From what you described, as long as you dont see fluid anywhere, and arent loosing fluid, I would look into the master cylinder.

 

i changed the master cylinder (used one ) i couldnt find new one in here so u think maybe its damaged coz as i said rear brakes not working neither the ABS ( it got only rear ABS brake )

 

Are you loosing fluid in the system? Do you notice leaks, or does the level in the master cylinder drop over time?

 

Adventurer,

Test procedure below.

DIAGNOSIS AND TESTING - MASTER CYLINDER/POWER BOOSTER

1. Start engine and check booster vacuum hose connections. A hissing noise indicates vacuum leak. Correct any vacuum leak before proceeding. 2. Stop engine and shift transmission into Neutral. 3. Pump brake pedal until all vacuum reserve in booster is depleted. 4. Press and hold brake pedal under light foot pressure. The pedal should hold firm, if the pedal falls away master cylinder is faulty (internal leakage). 5. Start engine and note pedal action. It should fall away slightly under light foot pressure then hold firm. If no pedal action is discernible, power booster, vacuum supply, or vacuum check valve is faulty. Proceed to the POWER BOOSTER VACUUM TEST. 6. If the POWER BOOSTER VACUUM TEST passes, rebuild booster vacuum reserve as follows: Release brake pedal. Increase engine speed to 1500 rpm, close the throttle and immediately turn off ignition to stop engine. 7. Wait a minimum of 90 seconds and try brake action again. Booster should provide two or more vacuum assisted pedal applications. If vacuum assist is not provided, booster is faulty.

POWER BOOSTER VACUUM TEST

1. Connect vacuum gauge to booster check valve with short length of hose and T-fitting. 2. Start and run engine at curb idle speed for one minute. 3. Observe the vacuum supply. If vacuum supply is not adequate, repair vacuum supply. 4. Clamp hose shut between intake vacuum source and check valve . 5. Stop engine and observe vacuum gauge . 6. If vacuum drops more than one inch HG (33 millibars) within 15 seconds, booster diaphragm or check valve is faulty.


POWER BOOSTER CHECK VALVE TEST

1. Disconnect vacuum hose from check valve. 2. Remove check valve and valve seal from booster. 3. Use a hand operated vacuum pump for test. 4. Apply 15-20 inches vacuum at large end of check valve. 5. Plug off the small end to prevent vacuum leakage. 6. Vacuum should hold steady. If gauge on pump indicates vacuum loss, check valve is faulty and should be replaced.

 

You may have air in the ABS system. I didn't know ABS was an option on these trucks. I do know that bleeding the ABS unit isn't as simple as bleeding the lines. I can't for the life of me remember how it works, but I think you need to have the engine running while you bleed. Just a thought as it sounds a lot like air in the lines.