I’ve been working on cars for years,but you know how it is, sometimes you just need to bounce an idea off someone else to see if your thinking is correct.
My grandson has a 1992 Ford TEmpo. Both rear hard brake lines have sprung leaks nearly in the same places near the fuel tank in the rear by the wheels. We are not taking any chances and are replacing the complete lines from master cyl. to rear brake on both sides.The car had no brakes at all and master went empty. After these repairs, I am having trouble getting any pedal after bleeding. I even bled at the master cyl. but didnt help. Am I correct in thinking I may have to remove and bench bleed the master cyl. again to get started right? Any suggestions would be appreciated. Thanks-Al
[b]First try bleeding the master cylinder by having an assistant pump the brake pedal, hold it, and then crack open the fittings at the master cylinder. Repeat this several times to make sure all the air has been bled from the master cylinder.
Then bleed the rest of the brake system in this order. Right rear, left front, left rear, right front.
Tester[/b]
If the master cylinder is level, you can probably get away without bench bleeding. I had this Camry with no brake fluid and I just bled them until finally I had a solid pedal. I bleed disc brakes by just opening the valve without pushing the pedal. It works great on the Tempo too. Experience. You have to push when bleeding the drum brakes.
Bleeding brakes by opening a wheel cylinder bleeder valve and letting it leak fluid while keeping the master cylinder filled is not good. With an assistant, you must pump up the brakes at the pedal and firmly push the pedal while opening and closing a bleeder valve. This will make turbulence that will help to clear debris that has settled at the bottom of a wheel cylinder. The bleeder valve is near the top of the wheel cylinder, not the bottom.
How stupid are you???
Opening a bleeder and letting the fluid flow is called gravity bleeding and it is done ALL the time. It doesn’t harm a thing.
A short length (4 inch) of vacuum hose fit snugly and pointing upward on the bleeder, half a turn open, while pumping the pedal and keeping the master cylinder from running dry will bleed the wheels. At the master cylinder, removing the line and pressing tightly on the M/C outlet with your thumb while someone pumps the pedal until substantial hydraulic pressure is developed will clear the air.
One mistake I have seen in bleeding brake systems is if your assistant interprets “pumping” as letting the pedal up while the bleeder valve is open, thus defeating the entire process. I never tell my assistant (usually my daughter) to “pump the brakes”. I ALWAYS say “press the pedal firmly until it hits the bottom and hold it there until I tell you to release it”.
I’ll say it again. You need pressure to make turbulence to stir up and clear debris from the bottom of the wheel cylinder. Gravity bleeding does not provide that.
This probably isn’t relevant, but I’ll post it just in case.
I recently got sufficiently annoyed about the low brake pedal on our 99 Camry to go after it. Replaced the brake fluid, bled everything. Still low.
Checked the calipers, found one that was siezed. Ahah says I. Found the problem. Fixed it. Now pedal goes to the floor even after the caliper is pumped back out to where it should be. Why me? says I.
Bled everything again. Pedal still goes to the floor.
Manually adjusted the rear shoes. Now the brakes are fine.
Doesn’t really make a lot of sense, but …
Bottom line. Air in your brake lines is certainly a likely cause of your problems, But don’t assume that the most recent problem (loss of fluid in your case) is the only possible cause of your brake problems.
Back Again with additional probs.I appreciate having a place to come to when a Job gets you down. We were just finishing up replacing all the lines master cyl. to wheel cyl-this car has porportioning valves under each rear line exit right on master cyl.- Now I have discovered a leak right at the master cyl.- one of the fittings there was an oddball-so I had to cut it off old line and reuse it double flaring it to the new line. I must admit, it’s been a few years since I double flared anything-I don’t think I got this right. I carefully followed all the proceedures but just cant seem to get a good even double flare-Anyone got any ideas I haven’t thought of? Or should I just keep trying.? Thanks-AL
you have to bleed the porportioning valves first then all of the bleeders.if that doesn’t work than the master is bad.
If you got the master cylinder from “Parts Plus” recently, or if you notice that it pushes fluid under pressure back into the resevoir when someone depresses the brake pedal, them the master cylinder is defective. Get another one from someone else until they resolve the problem.
“Gravity bleeding” is ok for flushing out all the old fluid and for filling the system. I do that with those one man bleeder kits but you can make your own out of a small bottle and clear vinyl tubing. I like the kits because they are convenient. I use four kits, one at each wheel. The collection bottles must be higher than the caliper or wheel cylinder so that expelled fluid has to flow up hill. That way if there is any suction for any reason, it will suck back fluid and not air.
But in the end, you still have to pressure bleed the system. Trapped air can get in a high spot like where the rear flex lines go over the top of the axle. Fluid will flow past the air bubble under low pressure conditions. It takes pressure to move the bubble.
I just need some clarification, I had the master cylinder run dry, does this mean I have to take off and bench bleed or can I bleed in place, if thats the case how do I do that?