Brakes and Anti-Lock Light

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
This '98 Disco I picked up for my son is the cleanest, smoothest, quietest V8 Rover I've ever owned. I'm sure I took it off road for the first time in it's life yesterday, when I made it tow the trailer down the hill to pick up the trees we've cut down.

However, there is some oddities with the brakes.

  1. The brakes and pads are "new". Look to have about 90% life left in them.
  2. The anti-lock braking does work, I've tested it in slippery conditions, and you can feel the feedback, and hear the buzzing just like normal.
  3. The anti-lock light is on at start-up, like normal.
  4. About 40% of the time, the light stays on after the initial check and driving.
  5. About 20% of the time, the light will come on at some point during the drive, wet or dry conditions.
  6. There is plenty of suction at the plenum to the brake booster, but I could not test the hose itself to see if it was blocked. It does not seem to have a leak.
  7. There does not seem to be any fluid leaks anywhere
The brake pedal...

  1. Is very soft when you start the car
  2. Seems a tiny bit soft after you've been driving a bit
  3. Does not compress when you repeatedly pump
  4. Does not lose compression when you hold it
Question: Could there be a leak in the booster at the firewall that makes it so the vacuum has a hard time building up at first, but catches up after a few minutes of driving? Is there anything else I should be looking at?
 

rocky

NAS-ROW Addict
I'm surprised its still working. My 95 lost is ABS after a few years.....The sensors are the likely culprit.
If the calipers and pads are ok, and rotors have the correct thickness, what kind of condition is the brake fluid in?
 

Red90

Well-known member
The booster in the Disco 1s do seem to have a high failure rate. Went through three used trucks last year and they were all bad. Pick up a vacuum pump tester. They are cheap.

There are also a million places for vacuum leaks and checking ti all out is a worthwhile exercise.
 

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
I'm surprised its still working. My 95 lost is ABS after a few years.....The sensors are the likely culprit.
If the calipers and pads are ok, and rotors have the correct thickness, what kind of condition is the brake fluid in?


I can't say when the fluid was bled, but it isn't bad looking. And I thought I remembered that the pedal would compress with pumping if air was in the lines, etc...


Everything seems to work, so I'm thinking it is something with the booster, or a sensor that is going bad and repeatedly tripping the warning. I want to make sure it isn't something that is going to fail, and cause the brakes to stop working.
 

Jeff B

Well-known member
I can't say when the fluid was bled, but it isn't bad looking.

I can't speak for others, but my opinion is if you dont know when it was bled... bleed it!

And actually, I'd replace all the fluid in an unknown truck.

Start at the reservoir, and suck out as much old fluid as possible. Empty it.
Then refill with new.
Then bleed and bleed a lot. So you've got new fluid everywhere.

I use the Motiv power bleeder.



.
 

ezzzzzzz

Well-known member
Tap the abs sensors down at each wheel to ensure minimum air gap. Completely bleed the system any way you choose because it sounds like you've got excessive air which easily compresses causing a soft pedal. I prefer to push fluid up to the reservoir from the calipers but conventional pump, hold, bleed will work fine.
 
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