• When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.

brake issue 69 b-body

moparfanUSA

Well-Known Member
Local time
1:43 PM
Joined
Apr 24, 2010
Messages
600
Reaction score
119
Location
nj
I was driving the car before putting it away for the winter and about an hour away from the house when I applied the brakes ( power drum brakes, auto trans) the pedal would stay where ever I pushed it to, half way, 3/4 ect, but the pedal would not return and the brakes would stay engaged until lifting the back up . I had to put my foot under the back side of the pedal to lift it back up. Had to do this all the way home. I did not lose any fluid, so there was no leak anywhere and I also checked the fluid in the master cyl....all good there. I thought it might be the master cyl itself so I replaced it and still had the same problem. There is no return spring on the pedal, so that's not it. I was thinking the power booster maybe was bad. I took off the vac. line coming from the intake to the booster and there was plenty vac going to the booster ( 20 inches of vac). Once the vac line is off the engine revs up a few 100 rpm....that's normal, when I hook it back up the rpm comes back down to normal, so good so far.
I figure that if the booster is leaking the engine should act like it has a vac leak and have higher RPM's.
So, I am not sure what could be wrong, Check Valve? something else? Any ideas?
I have the Midland Ross type booster with the white check valve and 2 nipples on it, one bigger and 1 smaller.
Why would my pedal not come back up each time? Stumped.....
 
I had a similar problem with my 71 GTX. Rear brakes dragging and pedal not returning fully. Problem was the rear rubber brake line to the rear end was acting like a check valve. Like a clogged artery. Pressure will push through but not return.
 
I will check that, but I am leaning towards the booster....auuuugggg, having to take that out......not looking forward to that!
 
Easy way to test the booster is to unbolt the master cylinder and then have someone step on the brake. This way you can make sure the rod does not pop out of place and someone inside can see if the pedal goes down and back up. If it does go back up, you know its not the booster.

The pedal still should return back up even if the rubber lines are collapsing. My Mom's sebring vert had the lines collapse but the pedal returned up. Rear disc brakes were still somewhat engaged though.

Could it be possible that you have rust in the bore of the master cylinder causing the piston inside to not return back which would push the pedal back up also? I always thought there was a return spring for the brake pedal though.
 
I will try it without the MC in place. Since I already tried 2 master cyls. and had the same result ( so I doubt that the bore has anything to do with it.)
I have ruled that out.
Thanks
 
You could always try cracking lines open at junctions when the pedal is down. If it goes up when you open up the line, you might get some air in the system but you know where the issue would be. Start as far back as possible, then work your way forward.
 
Start simple, check for leaks, then power bleed the system to eliminate possibility of air in the lines..

Next check would be replace the MC, bleed again...

Last is the power booster....
 
Auto Transport Service
Back
Top