93 850 ABS PROBLEM?

2volvoken · Post by **2volvoken** » 16 Feb 2005, 15:09

HAS ANYONE EXPERIENCED THIS PROBLEM. WHILE BRAKING THE BRAKE PEDAL WILL GO ALMOST TO THE FLOOR. THERE IS NO RHYME NOW REASON AS TO WHEN THIS HAPPENS.IT CAN HAPPEN WHILE BRAKING HARD OR SOFT BRAKING. THE ABS LIGHT NEVER COMES ON WHEN THIS HAPPENS. BRAKE FLUID IS FINE. VERY INTERMITTENT. THANKS 2VOLVOKEN

Tsquared · Post by **Tsquared** » 16 Feb 2005, 18:31

2volvoken wrote:HAS ANYONE EXPERIENCED THIS PROBLEM. WHILE BRAKING THE BRAKE PEDAL WILL GO ALMOST TO THE FLOOR. THERE IS NO RHYME NOW REASON AS TO WHEN THIS HAPPENS.IT CAN HAPPEN WHILE BRAKING HARD OR SOFT BRAKING. THE ABS LIGHT NEVER COMES ON WHEN THIS HAPPENS. BRAKE FLUID IS FINE. VERY INTERMITTENT. THANKS 2VOLVOKEN

ABS is the Anti-Lock Braking computer that controls the brakes to keep them from locking up during hard braking or braking on slippery surfaces.

As far as the pedal going to the floor you most likely have air in the brake lines, moisture in your fluid, a caliper/master cylinder that is failing, or a leak in a brake line.

To eliminate the air or moisture problem you need to purge your system of the old fluid. To do this you need a quart of DOT4 fluid. Remove as much fluid from your reservoir as possible (I have a kitchen baster that I use for this). Top off the reservoir with new fluid (it will be almost clear). With the passenger side read tire off and with a 3/8 open end wrench, take a 1/4 ID tube and place on the caliper bleeder nipple, (You will need a friend to assist by pressing the brake pedal and holding it) crack open the bleeder and let the old (dark color) fluid drain into a container. Tighten the bleeder, have your friend let up on the pedal and pump it back down and hold it, crack open the bleeder, tighten bleeder, have friend pump brake, repeat until fluid runs clear. Be sure to check the reservoir and top it off every 10th time you pump and clear the bleeder. Once the fluid runs clear tighten the bleeder, re-install the wheel and go to the other rear tire and repeat the process, then go to the front passenger tire and repeat, and finally go to the drivers side front last.

The process described will purge the old fluid. You go to the rear passenger first because it is the longest run - it will also take a long time to purge this line. In moist climates Volvo recommends doing this every two years. By pyrging the old fluid you will also be inspecting the calipers and hoses to see if their are any leaks. You will have covered all of the ares except for a bad master cylinder or caliper.