Reg Evans Posted February 3, 2017 Report Share Posted February 3, 2017 A newer vehicle I know but maybe someone here can solve this mystery. I'm having a problem with my 1956 Chryslers braking system. After driving 5 or 6 miles the brakes are locked up and the brake lights are on. This car came to me recently with new wheel cylinders, master cylinder and 2 of the 3 flex lines. The car is equipped with power brakes. After sitting for about an hour they will release but after another 5 or 6 miles they are locked again. I suspect the master cylinder relief port and am hoping it is simply the rod pushing on the master cylinder being out of adjustment. Any other ideas ? HELP !!! I want to drive this car !!! Quote Link to comment Share on other sites More sharing options...
knuckleharley Posted February 3, 2017 Report Share Posted February 3, 2017 3 minutes ago, Reg Evans said: A newer vehicle I know but maybe someone here can solve this mystery. I'm having a problem with my 1956 Chryslers braking system. After driving 5 or 6 miles the brakes are locked up and the brake lights are on. This car came to me recently with new wheel cylinders, master cylinder and 2 of the 3 flex lines. The car is equipped with power brakes. After sitting for about an hour they will release but after another 5 or 6 miles they are locked again. I suspect the master cylinder relief port and am hoping it is simply the rod pushing on the master cylinder being out of adjustment. Any other ideas ? HELP !!! I want to drive this car !!! Quote Link to comment Share on other sites More sharing options...
knuckleharley Posted February 3, 2017 Report Share Posted February 3, 2017 Only thing I can think of is either a bad master cylinder with a burr in it,or more likely,the pressure valve in the booster getting stuck. That sure is one purty car,and it's even got AC! 2 Quote Link to comment Share on other sites More sharing options...
classiccarjack Posted February 3, 2017 Report Share Posted February 3, 2017 I had a rubber hose that was partially blocked internally that caused a similar condition. Sadly it was a new part that let me down. Start by removing the lines from the wheel cylinders and master cylinder and check for a obstruction with compressed air. You will need some water handy to immediately clean up to avoid damaging the paint(Note: What ever you do, avoid putting pressurized air into your wheel cylinders and master cylinder to avoid damaging the piston cup seals). But first, try what Knuckleharley said. Make sure that the brake rod is the right length and check any other adjustments. I hope that this helps. I chased my tail for a day or so on my 1959 Dodge that had a similar issue..... 1 Quote Link to comment Share on other sites More sharing options...
classiccarjack Posted February 3, 2017 Report Share Posted February 3, 2017 I forgotten to mention my diagnosis.... The rubber line would let pressurized fluid pass into the wheel cylinders, but wouldn't allow it to bleed back. It was the rear hose at the differential in my case. It kept the entire system pressurized and caused my brake lights to stay on. By releasing the bleeder screws, I was able to limp it home a few short miles at a time to prevent my new brakes from overheating. OK, I will quit yappin and let you have your thread back.... 2 Quote Link to comment Share on other sites More sharing options...
DJ194950 Posted February 3, 2017 Report Share Posted February 3, 2017 Are your power assist brake an air (vacuum from motor) or hydraulic type (has power steer pump type setup).? I was think that possibly the assist pressure or vacuum was not relieving after each use and it slowly adds up to where it holds the brakes on. Just a thought. DJ Quote Link to comment Share on other sites More sharing options...
Reg Evans Posted February 3, 2017 Author Report Share Posted February 3, 2017 (edited) What do you get when you cross an elephant with a rhino.......eleifino Edited February 3, 2017 by Reg Evans Quote Link to comment Share on other sites More sharing options...
ply 51 Posted February 16, 2017 Report Share Posted February 16, 2017 Friend of mine had a simiular problem on his 58 desoto. Turned out to have been the pressure switch. Quote Link to comment Share on other sites More sharing options...
Reg Evans Posted February 16, 2017 Author Report Share Posted February 16, 2017 What is the pressure switch ? Do you mean the brake light switch ? Thanks Quote Link to comment Share on other sites More sharing options...
Plymouthy Adams Posted February 16, 2017 Report Share Posted February 16, 2017 (edited) IF you suspect a flex line you can usually verify by relieving the pressure on the brake side for instant release. Drive it till it occurs again and then crack the line on the supply side...if not instant relief, then it is a sign of internal hose restriction, very common... As known, supply is great amount of pressure, release is only what your springs can push back to the master.... Edited February 16, 2017 by Plymouthy Adams 1 Quote Link to comment Share on other sites More sharing options...
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