1987 Toyota Pickup brakes

Tiny
DLIESMAN
  • MEMBER
  • 1987 TOYOTA PICKUP
  • 2.2L
  • 4 CYL
  • 4WD
  • MANUAL
  • 189,000 MILES
25% of the time when I try to brake the pedal goes to the floor before I have any brakes. If I let it up then press it again it works fine. Already checked the following, pads are 50%, fluid level is good, no signs of a leak anywhere. My thoughts are master cylinder or booster just not sure which one. Any way to narrow it down to which I need to replace?
Wednesday, February 18th, 2015 AT 7:57 AM

3 Replies

Tiny
DR LOOT
  • MECHANIC
  • 2,311 POSTS
You can narrow it down by pumping up the brakes then hold steady pressure downwards if the brake pedal fades to the floor then it's a bad master cylinder, if the brake remains hard you could have air in the lines.
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Wednesday, February 18th, 2015 AT 8:26 AM
Tiny
DLIESMAN
  • MEMBER
  • 2 POSTS
The pedal does not fade. How could the system get air in it with no leaks and its been 4 yrs since I last worked on the brakes? I can be sitting a light with good pedal let off and press again and it will go to the floor, just sometimes. But sometimes hit them and it goes to the floor the 1st time let off hit them again and good pedal again.
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Wednesday, February 18th, 2015 AT 10:49 AM
Tiny
DR LOOT
  • MECHANIC
  • 2,311 POSTS
It sounds like you got a small leak, you did not mention in your original post that you remove the rear drums and check the wheel cylinders. If I were you I would start with bleeding. Doesn't cost anything but brake fluid.
Note: the brake bleeding order:
right rear
left rear
right front
left front wheels.

This should be done about once a year because the fluid is like a sponge and takes on water from the air via the reservoir. When the fluid gets to around 3% water it has a lower boiling point and you need to change it out because you don’t want it boiling when the brakes get hot. When the fluid boils it makes bubbles which can compress and then the brakes don’t work very well.
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Wednesday, February 18th, 2015 AT 8:16 PM

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