Hey everyone. This is probably going to be a wild goose chase, but here it goes. It is getting into the single digits in Upstate NY (sometimes below zero) and I am having weird brake issues. Sometimes the pedal is harder, sometimes it is softer. It usually stops about 1" above the gas pedal. Sometimes it can go a little bit lower if I am driving fast and I hit the brakes for the first time in a while. Sometimes the car stops on a dime, sometimes it takes a bit longer. There is just no consistency. My brake fluid was overfilled a few weeks ago. Now the fluid is at the MAX mark on the reservoir. Is the cold weather causing all this? Over the past year, I have had all 4 calipers, rotors, pads replaced along with the master cylinder (new) and the left front, rear and part of the right front line (all of them pass through the front left wheelwell). Also all 5 hoses have been replaced. I had 2 brake failures in NJ in one weekend last May caused by a jammed caliper that wore the pad completely out and caused the pad backing plate to hit the rotor. The shop down there replaced the master cylinder after the first one for about $400.
Cold weather causing brake problems?
ComputernerdBD
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Hey everyone. This is probably going to be a wild goose chase, but here it goes. It is getting into the single digits in Upstate NY (sometimes below zero) and I am having weird brake issues. Sometimes the pedal is harder, sometimes it is softer. It usually stops about 1" above the gas pedal. Sometimes it can go a little bit lower if I am driving fast and I hit the brakes for the first time in a while. Sometimes the car stops on a dime, sometimes it takes a bit longer. There is just no consistency. My brake fluid was overfilled a few weeks ago. Now the fluid is at the MAX mark on the reservoir. Is the cold weather causing all this? Over the past year, I have had all 4 calipers, rotors, pads replaced along with the master cylinder (new) and the left front, rear and part of the right front line (all of them pass through the front left wheelwell). Also all 5 hoses have been replaced. I had 2 brake failures in NJ in one weekend last May caused by a jammed caliper that wore the pad completely out and caused the pad backing plate to hit the rotor. The shop down there replaced the master cylinder after the first one for about $400.
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i kinda have the same problem. my peddle got very squishy when it turned cold out and i dont know whats causing it. im just gonna wait till my brakes pads need to be changed then flush my brake fluid and see it that helps.
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588 Posts
Brake fluid itself looks just fine. Still amber. That shop that replaced the master cylinder: I don't have to worry about going there anymore. The only reason why I went there is because the tow truck driver recommended it. It is part of a chain and they don't have any locations near where I live or go to college, so I don't need to worry about having to go to one again.
booster problem?
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588 Posts
Booster holds vacuum overnight. I could go outside right now and pump it and it will still have 3-4 pumps left on the reserve before it loses vacuum. Last time it was run was 27 hours ago. My main mechanic said the booster is fine last time he checked it.
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Lemme put my hydraulics hat on:
For your issue Computernerd, seeing that all your parts are new, I'd bleed thoroughly and try it out. Go from there.
For older parts, there are a couple things that can go "wrong" - air in the system (again) is one, and, worn parts, i.e., internal master cylinder tolerances, can cause a fluid bypass.
Additionally, cold weather will cause rubber to contract, get stiff, and lose its maleability. In this case, it's the sealing characteristics of the o-rings inside the system. Thousandths of an inch in internal parts wear, coupled with hard seals can be just enough for a fluid bypass internally = squishy pedal.
For your issue Computernerd, seeing that all your parts are new, I'd bleed thoroughly and try it out. Go from there.
For older parts, there are a couple things that can go "wrong" - air in the system (again) is one, and, worn parts, i.e., internal master cylinder tolerances, can cause a fluid bypass.
Additionally, cold weather will cause rubber to contract, get stiff, and lose its maleability. In this case, it's the sealing characteristics of the o-rings inside the system. Thousandths of an inch in internal parts wear, coupled with hard seals can be just enough for a fluid bypass internally = squishy pedal.
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Ok. That explains it then. I did notice something else. A couple days ago, it was around 50 degrees. The fluid in the master cylinder was a couple millimeters higher than the max line. When it is cold, it is right on the line.
What other seals are in the system that were not replaced with the parts I already mentioned? Nothing is leaking externally as far as I know.
What other seals are in the system that were not replaced with the parts I already mentioned? Nothing is leaking externally as far as I know.
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588 Posts
If there was any problem with the master cylinder, the pedal would be sinking to the floor at stoplights, correct? Sometimes the pedal does go down about 1/4-1/2" farther when stopping, but not to the floor. Other times it is firm or just okay. No fluid loss.
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Ok, a bit of an update. I drove the truck on a longer trip yesterday through the Catskill mountains. Roads were covered in snow and ice. Had to use 4WD for most of the way and ever other stop the ABS kicked in to keep the truck on the road. Only thing that kept me on the road during stops. I drove a total of about 200 miles yesterday in hazardous conditions. The brake fluid is still at the MAX line, but now the pedal is going down about 1/2" more every few brake applications. Could this be because the rotors are getting wet or ice covered or could I have air in the system? I am having the system bled when I have the tires rotated on Wednesday. Otherwise, the brakes work okay.
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588 Posts
There was air in the lines. I took it in today to get the tires rebalanced and the brakes bled and they were only able to bleed the front brakes because they claimed that the rear bleeders were seized, but they look fine and the calipers are only a year old. The pedal feels better and it doesn't sink another 1/4-1/2" nearly as often, meaning there is still a bit of air, but not nearly as much as before.
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