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1998 Toyota T-100 Brakes overheating

Tiny
LWWEAVER
  • MEMBER
  • 1998 TOYOTA T-100
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 150,000 MILES
Front brakes are vibrating and overheating. Pedal travel seems restricted. It does this intermittently. Pedal travel is normal when brakes are not tight. Front left brake hose was colapsed and replaced. Tried same thing with front right hose but did not fix the problem. Could master cylinder cause front brakes to tighten during driving? System only has master cylinder, hoses and calipers. Calipers and hoses are good?
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Friday, August 14th, 2009 AT 6:37 PM

13 Replies

Tiny
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When you say restricted, do you mean it is hard to press the brake pedal?
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Saturday, August 15th, 2009 AT 12:03 AM
Tiny
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There is very little travel to the brake pedal. Again, this seems to be intermittent. After coolling down, I drove the truck again and everything seemed normal. This has occurred several times now.
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Saturday, August 15th, 2009 AT 5:31 AM
Tiny
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Based on your description, I would say there is a problem with the power brake booster. What to do is have it vacuum tested to see if it holds vacuum or if there is a leak in the vacum line running to it. If it is loosing vacuum, you will lose power assist and it will feel restricted and it will be much harder to stop.
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Saturday, August 15th, 2009 AT 9:02 PM
Tiny
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Will this cause the calipers to close down on the rotors and overheat the brakes? My truck does not have ABS brakes. Is the power brake booster specific to ABS applications?
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Sunday, August 16th, 2009 AT 5:48 AM
Tiny
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No, it isn't specific to ABS brakes. However, it will make the brake harder to push. As far as the booster, it is the large round thing that the master cylender bolts to. It will feel like it restricts the brakes if it isn't working properly. However, it won't cause the brakes to hang up or stick on. I've never seen a master cylender do that either.

The vibration is most likely warped rotors. If they are warped badly enough, they may be making contact with the brake pads causing them to heat up. Also, when you replaced the brake hoses, are you sure the slides on the calipers are releasing as well as the caliper pistons?
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Sunday, August 16th, 2009 AT 8:21 PM
Tiny
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Yes the calipers are functioning normally.

Why does this occur intermittently? When I start driving everything is normal, nothing is rubbing, brake pedal is normal. After driving a while, the brake system seems to tighten up and the front right brake in particular begins to drag and pull the steering right. Drag gets harder and heats up, vibration begins. Then like it started it subsides and returns to normal. Warped rotors would not go away. Is there anything in the brake system that controls pressure besides applying the brakes. Could the power booster fail in this way?
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Sunday, August 16th, 2009 AT 8:52 PM
Tiny
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The proprtioning valve determines how much pressure goes to the front brakes and rear. However, it can't apply pressure until you press the brakes. You did say you replaced all rubber hoses correct? Also, the power brake booster wouldn't do this. And am I correct in assuming that it only happens after you use the brakes and doesn't start by itself?
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Sunday, August 16th, 2009 AT 10:40 PM
Tiny
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Yes, the system begins to tighten up after about 10 to 15 minutes of operation. Up until then the brake action is normal. Could the proportioning valve for the front brakes be failing and keeping pressure from releasing. The symptoms seem to cycle from tight back to normal.
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Monday, August 17th, 2009 AT 8:11 PM
Tiny
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I don't feel the proportioning valve could cause this, but stranger things have happened. The part that I'm confused about is it sounds like a bad caliper, or a bad rubber brake line that connects to the caliper, but you said they were both replaced.
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Monday, August 17th, 2009 AT 9:14 PM
Tiny
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Master cylinder replaced and problem solved. Still can't understand how the master cylinder can cause brake pressure to increase?
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Wednesday, August 19th, 2009 AT 9:09 PM
Tiny
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Master cylinders can cause the symptoms described when the rear piston is not returning fully due to contaminations. Rust forms when there is minor leaks from the seal and this would cause the pistons to stick.

Another possibility is that the seals are damaged due to oil in system and this would cause the seals to expand covering the return holes.

It is similar to brake pedal to booster push rod insufficient free travel. When this occurs, fluid is prevented from returning to reservoir. After driving some distance, the pressure builds up due to the fluids heating up and this would cause the wheels to lock up.

I have seen tham happen before.
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Thursday, August 20th, 2009 AT 1:22 PM
Tiny
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Thanks for the information. Sure would have been nice to have these insights about a week ago at the other end of this thread.

What does money back guarantee mean? I was never given an answer until the brakes were fixed.
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Thursday, August 20th, 2009 AT 9:47 PM
Tiny
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Maney back guarantee means if the goods or services provided is not up to expectations, you can request for a refund.

If you feel that we have not been helpful, you can always email to our administrator.
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Friday, August 21st, 2009 AT 12:51 PM

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