1967 bleeding brakes on an entire new brake system
I have a rebuilt dual master cylinder (with bleeder valves on it) and all new brake lines/calipers. I can not get the brake fluid out to the calibers...tried hand held vacuum pump and the traditional brake pedal pushing. What am I doing wrong?---both resevoirs are topped with fluid. I'm sure there is lot of air in the system because it is all new but I've pumped the brake pedal ~ 200 times with no fluid reaching the right real caliper. I've even tried bleeding the master cylinder at the master cylinder bleeder valves no results???
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Re: 1967 bleeding brakes on an entire new brake system
Dave, please clarify. you say your not getting any fluid out of the right rear caliper. is there fluid to the left rear? then you say you tried bleeding the master with no results. do you mean your not getting fluid out of the master? -
Re: 1967 bleeding brakes on an entire new brake system
No fluid in any of the lines. Correct...not able to get fluid out of the master. Both reservoirs are topped with fluidComment
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Re: 1967 bleeding brakes on an entire new brake system
Dave, two things come to mind. one disconnect the brake lines from the master. have a helper push the brake pedal down, hold your fingers over openings for brake lines, have helper release pedal. remove fingers. try several times. this should get fluid thru master. you could also use a pressure bleeder. it's called bench bleeding. you have to get the fluid past the piston that pushes it thru the system. i think it works better than using the bleeder valve. second, now i am not sure about corvettes but i have had this happen. make sure the push rod is in the booster that pushes the master cylinder. also make sure it is the right length. i have a 66 buick and it comes with two different masters. some were short shaft and some were long shaft. if you put a long shaft master in a short shaft car it will not work. and you can not install a short shaft master in a long shaft car. for buicks anyway. if you get fluid thru the master hook up the lines. then open the right rear and right front bleeders with a rubber tube over them going to a drain bucket. pump the brakes once or twice slowly. watch the master level as you enjoy a beer and let the brakes gravity bleed. when you have a constant drip from the lines close them and open the left sides. it works for me every time. but yes you need to finish by having a helper pump and hold the brakes to finish bleeding them to make sure you have all the air out. and please when you test the brakes go real slow. just in case you did not get all the air out. don't ask me why i say this, just take it from me.Comment
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Re: 1967 bleeding brakes on an entire new brake system
Dave------
If you have not already done so, you need to bench bleed the master cylinder. Bleeding at the master cylinder bleeder valves is not a substitute for this. In fact, after about 1972 GM deleted the bleeder valves entirely from Corvette master cylinders, PRODUCTION or earlier SERVICE.
To bleed the brakes, I recommend using a Motive Products pressure bleeder. These are not very expensive.In Appreciation of John HinckleyComment
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Re: 1967 bleeding brakes on an entire new brake system
Would the proportioning valve have anything to do with my problem??Comment
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Re: 1967 bleeding brakes on an entire new brake system
Dave------
It's not a proportioning valve; it's a brake fluid distribution block and pressure differential sensing switch. You should ensure that the piston is centered. However, I've actually forgotten how to do that; maybe someone else can chime in on it.In Appreciation of John HinckleyComment
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Re: 1967 bleeding brakes on an entire new brake system
Joe...What piston are you referring too. All the bleeder valves on the calipers and the 2 on the master cylinder are pushing out air when i step on the brake pedal ( I've tested all of them) so I know air is going thru the system. I just can't figure out why the brake fluid is not starting to push thru the system???Comment
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Re: 1967 bleeding brakes on an entire new brake system
Dave, until you bleed the master and have fluid coming out of the master you are not going anywhere. the master supplies the fluid to the rest of the system. bench bleed the master as i stated above. you need to get the fluid to come out of the master first.Comment
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Re: 1967 bleeding brakes on an entire new brake system
So it sounds like bleeding the master while in the car using the master bleeder valves won't work?Comment
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Re: 1967 bleeding brakes on an entire new brake system
Google "bench bleeding master cylinder". Some very good youtubes on that
GaryComment
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Re: 1967 bleeding brakes on an entire new brake system
correct. but you can do it in the car. just remove the brake lines and have a helper push the pedal in as you hold your fingers over the openings as i stated above.Comment
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Re: 1967 bleeding brakes on an entire new brake system
Sounds like this is what is happening! Yes, the MC should be bench bled first BUT as Joe stated above the piston in the new MC is not compatible with the adjustment on the brake pedal. There should be a procedure stated in the service manual to check and adjust this adjustment rod as it enters the MC. Probably the adjustment is blocking the fluid entering the MC. The MC will bench bleed just fine but if the rod is not adjusted correctly on the brake pedal it still won't work in the car!
Good luck,
JRComment
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Re: 1967 bleeding brakes on an entire new brake system
Dave------
There is a small piston in the brake fluid distribution block which deflects one way or the other if there is a pressure loss in the front or rear braking systems. This is what illuminates the dash brake warning light.In Appreciation of John HinckleyComment
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Re: 1967 bleeding brakes on an entire new brake system
You can get a cheap kit to bleed the m/c at most auto parts store. $10? It is inserted into one of the m/c line and is a simple hose you can hold to let run back into the m/c as someone is slowly working the pedal. you should get a solid stream out of both prior to going further. THEN start with the rear pass caliper opening both sides of the caliper. You MUST do both sides of the rears.I believe you do the outside first. This means NO Tires on the car so you have access. Then repeat left rear , right front then left front. Using a vacuum pump should speed things up or have your helper ready to do a lot of pumping.Comment
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