An easy way to get the air out of your master cylinder is at the lines. Crack open the lines on the master and have someone push down and hold the brake pedal, then tighten the lines. After the lines are tight you can let off the brake. Repeat this until you no longer see and bubbles or foamy looking fluid coming out, then you know the master cylinder is no longer holding air. Then bleed you brakes in a similar fashion rather than pumping in between bleeds, due to the low location of the master cylinder if you pump you can actually allow the air back into the master cavitating (churning up bubbles) the fluid in the piston bores. It works on master cylinders and abs modules and clutches bleeding this way. As a matter of fact that is the only way to bleed a Teeves system so don't be scared that it won't work and anyone who has had the agony of putting a clutch in a ranger knows it works on clutches. If you find no air there, and no air at the wheels it is time to adjust the rod on the booster because it is too short. A high dollar way of checking that would be to plumb in a brake line pressure gauge and see if pressure increases relative with pedal travel. Cheap way is the harder and longer you push the pedal the stronger the stream the bleeders should piss. I know something about brakes but am lost with a 216 swap.
Ok I just bench bled the master, and then the lines. The brakes are a little better now, but they still pretty much go to the floor. really need someone else here to help me bleed them. I have one of those clear hoses with a check valve in it, but it doesnt seem to really work.
How much play is in the pedal before it ingages the booster? there should be no room between the plunger on the booster and the master, you can adjust the booster plunger on some boosters. you could be loosing all your pedal before it ingages the master form the booster.
It measured it out, and it seems that there it least 15 thousanths gap between the booster and the master. that said the pedal feels like it moves at least 2 inches before anything happens.
When you are bleeding the system are you "pumping" the pedal??? When there is alot of air in the system - pumping the pedal can "froth" the fluid - you really ought to avoid the pumping in an effort to avoid the froth. Once you get things CLOSE bleedwise then you can resume your normal bleeding practices. One problem may be those coiled lines. When there's a coil liek that and you have lots of air in the system - you can actually p*** the fluid past the bubble effectively bleeding nothing at all. The solution is to move more fluid - faster - sometimes pumping the pedal just don't make anything happen fast enough - in these cir***stances a pressure bleeder may be more effective than a vac bleeder - I'm not saying a vac bleeder is a bad thing but if it don't have enough flow - you can chase your tail a bit. The last one I did like this - I got frustrated and used my thumb as described above. Since you typically make so little progress with each pump - tightening and loosening a bleeder valve was for the birds (for me - THAT one time) once I got close then I could resume "normal" bleeding techniques. Have you tried bleeding both systems - or are you stuck on one side (front / back) - What you describe almost sounds like a bad M/C - how did it bench bleed????? EDIT: The .015" AIN'T your problem
the master bench bled fine. It had a bunch of air in it, but that was expected. I fixed the coils that looped around the trans. I still have 1 coil because the line is so long, but its laying on its side, to it should bleed. When I bleed, I push the pedal all the way down and then take about 3-5 seconds to let it up. I do this about 30 times for each wheel. I have bled both systems, but they both need more work.
We always chuckle when we see teflon tape on bleeder screws because we all know the threads don't do the sealing BUT!!!! in your case of using a vac bleeder you may want to get some thread sealer and try it. I'd use the teflon goo in a can - it won't hurt anything even if you leave it there. But you MAY at some later date find yourself defending your actions when some chuckle head see it and proceeds to tell you why you shouldn't use it EDIT: BTW What all has been changed thus far prior to this issue. The reason I ask is that IF you possibly just changed calipers - I'd want to make sure you don;t have those "low drag" GM calipers made in the 80's. Those calipers were made with a "special" piston seal that actually retracted the piston to prevent any pad drag in an effort to maximize mileage. The problem with them is that you HAVE to run the appropriate FAST FILL M/C because of the large volume of fluid moved back when the pistons retract. IF by chance you have used those calipers with a "regular" M/C you're gonna have a perceived bleeding issue you won't ever be able to rectify. This issue gets cloudy when the calipers get rebuilt - some guy send up using those calipers and swear they have no problems with them - I suspect in those cases the rebuilder put "regular" seals in them. Food for thought.
Thats good info. Thanks!!! The calipers are supposedly from early 70's full size chevys. But to be honest I am not sure. I just bought 15 feet of clear line so that I can sit in the car and bleed the brakes back into the master. Hopefully that will work better.
UPDATE: Ok I basically bench bled the entire system with tubing going from the bleeders clear to the master. I got a bunch of air out! Now with the car off I get a good pedal after about 1 1/2 inches of pedal movement. With the car running, I dont get a good pedal till its over half way down. How do I adjust for that?
my 2 cents learned the hard way many many years ago. When bench bleeding a master cyl, do not bottom out the pistons, doing so can damage the seals and it will never seal and remain "spongy" feeling
I read thru the posts again and tried to see what your back brakes were, sorry if I missed it. I have seen too much mechanical play in the rear drums give a soft pedal.
The rears are drums. Thanks so much for all the replies. I am getting a good pedal now, but its about 1/2 way thru the stroke with the car on. With the car off its fine. I need to figure out how to get the play out of it with the car on.
Now we're gettin' somewhere!!! So to restate the pedal is GOOD when the car is off - Yes! Air sounds to be gone!! OK now we need to see about the booster, but first let's remember how these things work. The booster is basically two halves - one half nearest the m/c is under vacuum pretty much full time - well at least when the motor's running. The other half also has vacuum WHEN your NOT using the brakes - vacuum on both sides pretty much negate each other and it sits there in a neutral state. Step on the pedal and you activate a valve that allows the front (nearest the m/c) to maintain it's vacuum while the REAR LEAKS and atmospheric pressure now acts against the m/c providing the ***IST. LEt off the pedal and we plug the "leak" in the rear chamber and allow it to again become balanced with the front. Next they add in a check valve so that the vacuum maintained in that front half remains at the numerically highest vac reading. This is two fold - should your motor STALL for instance - you still have this RESERVE of vacuum to allow you to depress your brakes and have them still be fully functional. So.....in use what does this mean?? Well first off you should be able to get in your vehicle and depress the pedal (motor not running) - should you depress it several times you will eventually "use up" your vacuum supply in that front reservoir - each time when you let off the pedal you should hear that vacuum leak out of the REAR reservoir. That's a good thing. If you hear nothing then you have to suspect a leak in your check valve or the vacuum port seal. ANother test is to get in your car (not after this previosu test) and depress the pedal - you should have some vac ***ist - start the motor - as the motor idles (high vac) you should get additional vac on the front diaphram - which you'll notice right away as the pedal will automatically drop as that vacuum builds. IF you have issues with either of these tests - something is definitely amiss with your brake booster. EDIT: It's been awhile since I thought this thru in my head - so I THINK I stated it correctly - if not please feel free to call me a nit wit.
Well I can see that one of the problems I have is that there is no check valve for the booster. Just a vacuum line from the booster to the carb. So I should get a check valve. Is there a way to adjust it so that when the booster has a vacuum the pedal doesnt drop as far before becoming firm?
The check valve is usually built into the 90deg fitting off the booster. I'm not aware of an adjustment there - what pedal ***y are you using?
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