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Brake system

Tiny
UNKLE
  • MEMBER
  • 1995 INTERNATIONAL TRUCK
  • V8
  • 2WD
  • AUTOMATIC
  • 63,000 MILES
I just had the front brake calipers pads rotors and bearings replaced and a master cylinder. I have driven one hundred miles and the pedal went to the floor. I was able to pump the brakes and get it stopped. I noticed that the reservoir was filled over the max line. I opened the top and the fluid sprayed out (like a hot radiator that was opened). Weird as the fluid was not that hot, but very warm bath water. I siphoned out approximately a quart and added in fresh. Pumped the brakes to get the new stuff mixed in and it seemed to work.(Temporary fix only and is going to a different shop tomorrow) But what has caused this? I have been toying with cars for years and have not seen this before. By the way, this is an International truck +/- 44,000lbs.
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Thursday, June 28th, 2018 AT 2:24 PM

11 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good evening.

It sounds like the shop that replaced the pads just pried back the caliper pistons and the fluid went back to the master and overfilled it. When you started driving it, the pads were partially applied generating heat and that went right to the fluid. That cause the fluid to boil and that resulted in air. That is why the pedal went to the floor.

I am concerned that the master cylinder is damaged. The seals may be damaged internally. When you go to the next shop, tell them what happened and see if they agree. Overfilling it put pressure on the fluid which went to the lines.

Roy
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Thursday, June 28th, 2018 AT 4:58 PM
Tiny
UNKLE
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Thank you, but they did replace the caliper as they did this in the lot next to my truck that I was working from and was watching them intermittently.
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Friday, June 29th, 2018 AT 5:16 AM
Tiny
ASEMASTER6371
  • MECHANIC
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Okay, the next thing I would check is the brake hoses. If they are collapsed, they will not allow the calipers to totally release and it will heat up the fluid and boil it.

Roy
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Friday, June 29th, 2018 AT 5:50 AM
Tiny
UNKLE
  • MEMBER
  • 6 POSTS
Great thank you, I will find out from International when they fix it.
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Friday, June 29th, 2018 AT 5:53 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Sounds good.
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Friday, June 29th, 2018 AT 7:50 AM
Tiny
UNKLE
  • MEMBER
  • 6 POSTS
Update: International spent eight hours and cannot find the leak. They are looking to the electrical system to see if something is causing something to function? I thought that brake systems are closed ie reservoir, master cylinder, lines, calipers. Earlier I stated I removed some brake fluid. I noticed that it was dirty and very thin almost like water. Could the first company added old or contaminated fluid? Or could there be an internal issue with my left front caliper? It was replaced two times the first one would not release so they warrantied that one and replace with a new one. Still baffled. Thank you for the help.
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Monday, July 9th, 2018 AT 6:34 AM
Tiny
ASEMASTER6371
  • MECHANIC
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Okay, when you removed the cover for the fluid, was the gasket swelled up two times its size? That would indicate an oil in the system instead of brake fluid.

You should change all the fluid not just the fluid in the master.

Roy
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Monday, July 9th, 2018 AT 6:43 AM
Tiny
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The gasket was not swelled. The liquid was dark and dirty it did not smell burnt but rancid like spoiled veggie oil.
I believe that they changed the fluid and will check when I call later today. Vehicle is in for some other repairs also.
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Monday, July 9th, 2018 AT 8:21 AM
Tiny
ASEMASTER6371
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Yes, have them change and flush the entire system. You need to get all the old out and new fluid in the system.

Roy

https://www.2carpros.com/articles/how-to-bleed-or-flush-a-car-brake-system
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Monday, July 9th, 2018 AT 8:25 AM
Tiny
UNKLE
  • MEMBER
  • 6 POSTS
International came back with this. There is an electrical connection that is shorting out something to stay open and that is how the air is getting into the brake system. They are changing a wiring harness. And fully draining the brake fluid and flushing it out.
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Thursday, July 12th, 2018 AT 1:17 PM
Tiny
ASEMASTER6371
  • MECHANIC
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Okay, if you have ABS the vent solenoid may be open drawing air into the system.

Makes sense.

Roy
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Thursday, July 12th, 2018 AT 6:47 PM

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