[pavel]

The other day, I got a quick hint that somethings wrong with my brakes in our low mileage '96 Disco I - went over a slight pothole and the ABS system sent a short pulse back through the pedal along with that typical ABS sound. This only lasted a for a second.

Today, the first time I stepped on the brake, the pedal was stuck and then it gave way and started to work properly again. There were no further problems.

Clearly something is wrong...worn master cylinder? Bad accumulator or other power brake or ABS component?

front rotors/all calipers/pads are relatively new - 1-2 years old.

Can anyone shed any light on this problem?

 

[Jagfixer]

After a days use, is it still sticking or was it a one time thing?

 

[pavel]

It happened once, two days ago when I first applied the brakes after start up. Then again yesterday a few minutes after start up - that time the brakes were fine until I went over a very minor bump and the ABS kicked in for a second or so and the pedal was stuck for just an instant - or maybe the pedal "pulsed". Very strange.

 

[Jagfixer]

Might flush brake fluid. Flush the ABS and brakes.

 

[pavel]

I flushed the brake fluid (dot 4) last year but have no idea how to flush the ABS pump and controller itself - never thought of that.

 

[Jagfixer]

In the RAVE or just pump the system entirely with a couple qt bottles of fluid. I used five qts one time on a hard to clean system.

 

[pavel]

Sounds like a good plan - brake fluid isn't expensive.

I phoned Atlantic British - they do not carry the Autel brand code readers which might be able to read the ABS codes on my '96 Disco (but I doubt it). The tech recommended I check that the ABS wheel sensors are properly seated. I did replace the rotors last year and might not have put the sensors back all the way. Again, another inexpensive procedure.

Phoned the dealer... they have increased their hourly rate to $150. Ouch!

 

[Jagfixer]

If ABS light is not on reading is null. Check sensors as above and flush the ABS hydraulics.

 

[pavel]

It became obvious over a couple of weeks of driving, that it was the ABS that was causing the problem... every time the ABS light came on the brakes returned to normal function (this happened often a few minutes into driving - after a dozen or so brake applications complete with sticky pedal, strange grunting sounds etc.). So, I was pretty sure it is not a master cylinder or booster problem. In other words, with the ABS off, the brakes were OK.

Yesterday, I found time to pull the front wheels and pull the front ABS sensors. The ends that face the cog wheel were coated in grey coloured grease. Once I cleaned the ends of the two sensors and reseated them, the problem has disappeared. I am tempting fate a little, but I may have solved this strange malfunction. It does seem odd that a bit of "One Shot" grease could interrupt the ABS signal to the sensors. I'm pretty sure the sensors were fully in place before the "repair."

I'll report back if the problem re-appears but have already received a big kiss and a squeeze from the Mrs...

Could this be another cheap repair?

Pavel