im having trouble bleeding my brakes . no matter how i bleed them , there is always more air in the lines . any ideas appreciated ...................... steve
Well, I'd start out with a detailed description of your car or truck and the brake system currently installed on it.
Start at the Master. Is it pumping solid fluid? Bleed it to make sure. Then, back off and tighten every fitting on the section that has an issue. Make sure the bleeder is a reasonably tight fit in the wheel cylinders and calipers. Last, how are you bleeding? 2 person push/open, close/release? Vacuum?
A recent thread about brake problems had the poster find a cracked fitting after he checked over the whole system.
This is a hard question to answer but these thigs are very hard to bleed all the air out of. Start with the right rear wheel, then the left rear, the right front. Left front last. Did you bench bleed the master cylinder? Try bleeding it on the car. Just crack the fitting to bleed. Do you use a proportioning valve? These need to be bled, too. Power brakes? Bleeding needs to be done with the engine turned off. Residual pressure valves can be problematic . I don't like them and won't use them. It would be helpful if you can find someone that can reverse bleed it or use a pressure bleeder at the master cylinder. Be sure tour pedal free play is correct. If you're not bald, you probably will be. These things can make you pull your hair out.
I shun residual valves too, with a master on the firewall, you won't need one. Look for air traps, like a line higher than the master. Are you losing fluid? I give this piece of advice in cases like yours. Clean up all the fittings with carb cleaner or even spray some soapy water on them. Go back out in the dark, with a flashlight. Wet spots show up like magic if you have one. How old is the master? Lately I have heard of more bad ones right out of the box. When I bled my car, I borrowed a vacuum bleeder, it made things easier.
There seem to be many posts about this problem recently. I have been following each and every one very closely since I have been having the same problems. I have found the blue paper shop towels invaluable in locating leaky brake line fittings used with a powerful flashlight as has been mentioned. A few things I have learned from this experience are that it seems as though I need to tighten things way tighter than I feel comfortable doing, replacement calipers are very difficult to seal the flex hoses to since either the copper washers are faulty or the caliper mounting surface is just plain to rough at the mounting surface since they are no longer spot faced after shot blasting, and finally the overall quality of the parts we receive from the parts store is extremely subpar. I am currently waiting for the third master cylinder, have purchased six calipers before I got two to seal and gone through more copper washers than I can count. Yet we continue because we enjoy the results.
Good point on surface finishes. That is one of the 1st places to look with disc brake conversions. Although hard to spot with the wheels on.
Even with drum brakes? I've always been under the impression that you wanted to keep at lest some minimal pressure at the wheel cylinders when the brakes were released to work against the tension of the shoe return springs.
Its a shame that the collective wisdom and experience on this forum is not concentrated into one thread or sub-forum for brakes.
couple of things if it is that one location. 1. bleeder screw not seating well and drawing air in. remove and inspect the screw tip and seat in the cylinder. 1a. same thing with a copper sealing washer at the tee fitting on the rear end, or bad flare connection at the wheel cyl. 2. If you have no residual valve and the drum brake wheel cylinders have no metal expansion cup behind the rubber cups, they can draw air in on retraction. That is the main function of drum residual pressure, keep the cups sealing.
Speed Bleeder valves are something to try. They have a sealant to keep air from entering around the threads, and will only let fluid flow out while bleeding. Then tighten them up and good to go.
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