David K Posted October 13, 2002 Share Posted October 13, 2002 Alright i rebuilt everything except the Master Cylinder. I bled the brakes for about an hour to make sure they were done right. New pads, seals, and fluid. Now when i use my brake, the pedal is soft and it is low. I pump it 2 times before i brake and it is VERY nice and stiff. What the heck is going on here? I dont see any air in the lines anymore. Ive even tapped the lines while i had 2 friends pumping and bleeding. any help is aprieciated. Quote Link to comment Share on other sites More sharing options...
Guest greimann Posted October 14, 2002 Share Posted October 14, 2002 Dave, that is still a symptom of air bubbles. Make sure you are bleeding correctly: Open bleed, push pedal and hold, close bleed and bring pedal back up. Do that every stroke. Also do the right rear, left rear, right front and left front in that order. Quote Link to comment Share on other sites More sharing options...
Guest Drewz Posted October 14, 2002 Share Posted October 14, 2002 Also now that it has a mile or 5 on it readjust the rear to bring the pedal up higher. That is if you aren't running rear disc. If you are running rear disc than air in the lines or a line that is only 90% tight sounds like the problem. $0.02 here Quote Link to comment Share on other sites More sharing options...
David K Posted October 14, 2002 Author Share Posted October 14, 2002 hmmm the way i have always done it is: Have a friend push down on the brake. open bleeder screw, close bleeder screw, have friend release pedal repeat 3 times on each brake. is this wrong? i start with the passenger rear, go to driver rear, passenger front, and then driver front. how do i bleed the master cylinder? Quote Link to comment Share on other sites More sharing options...
Guest Carlissimo Posted October 14, 2002 Share Posted October 14, 2002 Definately air in there somewhere. May be in the master cylinder area. Look for the nipples on the side of the master cylinder itself and use the same procedure as with the wheels. Take care not to let any air get in at the end of each stroke of the pedal. A hose that fits tight over the nipple helps keep the air out even if there is a little "reverse flow". If all else fails, try opening up the pads at the disks. The idea is to push the fluid back up to the master cylider and flush any bubbles there out the top. Be careful not to cause the resouvoirs to overflow. Then there is a power bleeder.... I've never tried one of those though.... Good luck ! Quote Link to comment Share on other sites More sharing options...
David K Posted October 14, 2002 Author Share Posted October 14, 2002 but i need to know exactly how to bleed. do i open the screws after the pedal has been pressed all the way down, or do i open the screws and then have the pedal pressed down, and then close before releasing? i may have to bug Dave G at his home again, dont wanna do that Quote Link to comment Share on other sites More sharing options...
CruxGNZ Posted October 14, 2002 Share Posted October 14, 2002 What I've done that has worked for me in the past is to: - bleed the farthest to the nearest from the MC. RR, LR, RF, LF (Like Greimann stated). - Have freind pump the brakes up until they feel solid (maybe 4-5 times), and hold pressure on the brake pedal. - Open bleeder and have freind tell you when the pedal hits the floor, as soon as that happens, close the bleeder. - Repeat process untill brake lines have no bubbles. I always bench bleed Master cylinders before installing them. If you get a new MC or rebuilt, they usually come with instructions on how to do this. Oops, just saw that you don't have a new or rebuilt MC. Do you have the bleeders on the side of your MC? !M! Quote Link to comment Share on other sites More sharing options...
David K Posted October 14, 2002 Author Share Posted October 14, 2002 yeah the i have a 2 bleeder screws, one for the front and 1 for the rear. i was having a friend pump the brakes and stand on it. i then open the bleeder and when the pedal hits the floor, i close it and then he releases and then we repeat. I notice something though. at the end before the pedal hits the floor, a bunch of foamy air/fluid comes spitting out of the front reseviour into the hose i use to bleed. where in the heck is this air coming from? Quote Link to comment Share on other sites More sharing options...
A. G. Olphart Posted October 14, 2002 Share Posted October 14, 2002 Have a helper pump the brakes 3 or 4 times fairly slowly (or until he/she feels brake pressure if sooner) and then yell 'ready' (or whatever) while holding the pedal down. That is you cue to quickly open a bleeder valve, and close it as soon as the flow of bubbles or fluid diminishes. If you close it while stuff is still coming out, there will not be any air going back into the system through your bleeder. As soon as your bleeder is closed yell 'closed' or something to let your helper know it is safe to release the brake pedal and pump again. Continue at each wheel until you have clean fluid with no bubbles for 3 or 4 cycles, then go to the next wheel. Very fast pumping is bad because it traps bubbles in the fluid. If your helper lets the master cylinder go dry, you will essentially be starting over- not a good thing. The master cylinder is generally bled pior to being bolted in place... one works the piston slowly, and the little bubbles come up through the holes in the bottom of the reservoirs. A slow process. An assistant with thumbs over the brake line openings can help- the thumbs act as flapper valves. If your master didn't go dry while you had the system open it shouldn't need bleeding. If it did go dry, bleed it first. I think you had the wheel sequence right- start with the wheel farthest from the master, and work closer. When you actually get pressure up at the rear (assuming drum brakes) the shoes will tend to center themselves and often need readjustment. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted October 14, 2002 Share Posted October 14, 2002 If you still suspect its air in the lines, it might be worth a few bucks to take it to a shop and have them power bleed it with pressure. At least that will eliminate that as a possibility. As you might know, a bad master cylinder typically will slowly drop if you apply the brakes, you feel it sink. I also like to bleed into fluid as well. I run a tube off the bleeder barb into a bottle of brake fluid. That way if it does suck anything back in, its fluid and not air. Just an idea of course. Regards, Lone Quote Link to comment Share on other sites More sharing options...
David K Posted October 14, 2002 Author Share Posted October 14, 2002 well....what causes this? im driving. i want to brake. i push the pedal and it is very soft and i need to press it far to get the car to stop aggressivly. I pump it 2 times before i brake. i brake immediatly after i pump it 2 times and it workd great! the car stops on a dime! if i hold it after the car has stopped, it will sink a little lower. i believe i am on the right track to making these brakes work, but im having this bias problem that is just messing with my head. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted October 14, 2002 Share Posted October 14, 2002 David sounds like the master cylinder is not holding the fluid pressure. I change master cylinders when this happens/never could rebuild them with new seals. Quote Link to comment Share on other sites More sharing options...
David K Posted October 14, 2002 Author Share Posted October 14, 2002 cool...gonna get a new mc tommorow. thanks guys Quote Link to comment Share on other sites More sharing options...
RB30-ZED Posted October 14, 2002 Share Posted October 14, 2002 Just two points that my help. 1/ Never push a pedal right to the floor while bleeding, unless its a new master cylinder, as dirt and corrosion has built up in the section of cylinder that hasn't had the seal moving in it for 20 plus years, may damage the old seals and cause internal leakage. 2/ If pumping the pedal gives you a high, hard pedal, then its not air in the system but to much movement , due to unadjusted brakes or pad knock back or leaking master cylinder seals. Air in the system will remain spongy no mater how many times you pump the pedal. Steven Quote Link to comment Share on other sites More sharing options...
Guest Drewz Posted October 14, 2002 Share Posted October 14, 2002 RB hit on what I said earlier. The pads could be seated or have shifted and now are maladjusted. Also last week I did the brakes on my 4x4 and the line at the master was letting air in and it needed to be cinched up that little bit. Also when bench bleeding a new or used master avoid pushing the plunger all the way in as you could "stroke" the new or used master. The term "stroke" means that no master cylinder when applied goes 100% to the length of its full stroke. It can and does damage the internal seals if you bottom it out when bench bleeding. If you want to find out the problem line, wheel, or what ever it is here is a trick I used in the shop all the time. You can apply a set of vicegrip to the four hoses on all four wheels, don't crush the hoses just clamp them snug enough that the fluid can't travel through the hose. When all four are blocked off press the pedal and it should be hard as a rock since fluid cannot travel. If it isn't that means the fluid is bypassing internally in the master and therfore the master is bad. If the pedal is good have a friend/helper release each pair of vice grips while pushing on the pedal and see if when one is released if the pedal drops dramatically. The rear should drop slightly more than the front as the front disc pads ride closer to the rotors than the shoes do in relation to the drums. This will let you know where the problem lies.I would try this method to ensure you aren't replacing a good master. Please do not apply too much pressure with the vice grips since you will crush the hose instead of crimping it. I have line locks from Mac Tools for doing this but before I bought them I used this method a hundred times. Good luck!!!!! Quote Link to comment Share on other sites More sharing options...
David K Posted October 14, 2002 Author Share Posted October 14, 2002 hey thanks for that tip. i will try the vice grip thing before i change the MC tommorow. I am also very tired, so i will reply to this in length tommorow. you are part of a clan? i see your sig. i play halflife stuff. i run a clan for DoD. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted October 14, 2002 Share Posted October 14, 2002 Great Tip! ..Drew Z... sounds like it could be a money saving test Quote Link to comment Share on other sites More sharing options...
Guest Drewz Posted October 14, 2002 Share Posted October 14, 2002 David what else you play?? I play Rogue Spear, Urban Ops, Black Thorn, America's Army. I love paramilitary games. I learned that brake tip almost 10 years ago and boy I saved alot of time and customers money by using it. I love sharing!!!!! LMAO!! Quote Link to comment Share on other sites More sharing options...
David K Posted October 14, 2002 Author Share Posted October 14, 2002 i just play all halflife games. DoD, CS, Desert Crisis, Tour of Duty..... am i supposed to hear hissing when i press the brakes? Quote Link to comment Share on other sites More sharing options...
Guest Drewz Posted October 15, 2002 Share Posted October 15, 2002 The hissing sounds like the booster leaking and could be on the way out. Several of the guys I play along with play DOD and CS. Quote Link to comment Share on other sites More sharing options...
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