1995 GMC Safari 6 cyl All Wheel Drive Automatic
I changed out the calipers a couple of years ago, manually bled the system and everything worked fine, for about 18 months when the system started pulling to the left. Ok, sounded like the drivers side caliper was hanging up. So I have replaced the calipers and found that the drivers side caliper was hanging up. Now I seem t have a new problem. I have very little fluid flow to the passengers side caliper I have visually inspected all the lines and do not see any kinks or other problems. My question is this What could be causing the low flow? The ABS light is on now as is the brake light. Alldatadiy. Com does not give me a procedure for troubleshooting the braking system. Can you folks give me a path to go in? Thanks!
Hi cmangell. Welcome to the forum. Simple problem; easy fix. There is a valve in the master cylinder that is normally centered and leaves all of the ports open. Think of a level and balanced teeter totter. When anything happens to cause a difference in fluid pressure between the two hydraulic circuits, that valve moves to block off two ports and that stops fluid from flowing to a potential leak. Pedal bleeding with a helper can cause the same thing if the pedal is pressed more than half way to the floor. That is always something to avoid with any vehicle because it runs the lip seals over crud and corrosion in the bottom halves of the bores where they don't normally travel.
The fix to recenter the valve is to open one of the bleeder screws that isn't flowing fluid, and give it a short burst of compressed air. Not enough to force air all the way up to the master cylinder; just enough so fluid starts flowing again. Let that wheel gravity bleed. Close the bleeder, stroke the pedal about 1/3 of the way until the piston has applied, then crack the bleeder open once more to get the last couple of bubbles out.