Quote:
Originally Posted by SaxAndLiz
Are there any other tests I can do? I was thinking of topping off and bleeding the brakes. I know a bad master cylinder can cause the problem intermittently. Just hate throwing parts at a problem without being sure.
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According to the FSM these are the following causes of a low or spongy brake pedal:
1) Fluid leaks
2) Air in system
3) Piston seals
4) Rear brake shoe clearance out of adjustment
5) Faulty master cylinder
6) Booster push rod out of adjustment
You've confirmed there's no external leaks which eliminates 1 and 3. Air in the system (99 percent of the time) does not cause an intermittent low brake pedal so 2 is out. Rear brake shoe clearance out of adjustment and booster push rod out of adjustment also don't cause an intermittent low brake pedal so 4 and 6 are out as well. That just leaves 5. Faulty master cylinder.
If you replace the master cylinder make sure to bleed the master cylinder per the factory service manual instructions. If you don't you'll have a bad pedal again.
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2000 SR5 V6 Manual 4WD
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2000 Limited V6 Auto E-Locker Sold 3/2022