Hello, new member here but not new to the forum - I have owned a '98 Disco for about a year and a half now and have found this site a very useful resource. Anyway, I'm having a problem with my brakes. I've searched the forum but I can't quite find anything that describes my situation.

A couple months ago I replaced my brake pads and bled the lines. Other than normal wear there wasn't a problem, just routine maintenance. The vehicle was stopping just fine with a firm brake pedal both before and after the pad replacement. However, a couple days ago while waiting at a traffic signal with my foot on the brake I could feel the pedal very slowly depressing towards the floor under the slight pressure of my foot. A few seconds later the vehicle started to creep forward as the holding power of the brakes was releasing. I gave it a quick pump and the pedal had firm pressure again and the brakes stopped the vehicle. A few seconds later this same situation repeated, and has every time I've stopped since then.

I immediately checked for leaks (of which none were found, and the fluid reservoir was just as full as it was the day I topped it off after the pad replacement). I'm curious if anyone else has experienced this and could give me some advice on where to proceed on this problem. I'm very competent mechanically, on a previous vehicle I owned I had a similar issue which turned out to be the master cylinder. That car however was 40 years old and was much more simple to troubleshoot and diagnose.

I would really appreciate any advice and help I can get from other forum members before I purchase any unnecessary parts. Thank you.

 

Sounds like the master cylinder. Do not replace with an aftermarket part. There are plenty of reports of problems with non-OEM master cylinders.

 

Either a bad master cylinder or a vacuum leak.
In your driveway with the engine off pump up the brakes and hold, does the pedal still go to the floor?
Yes?
Master cylinder.
No?
Vacuum leak.
The power brakes are vacuum assist.

 

How are your brake lines? Stock rubber? Any sign of ballooning? If okay....

Agree w/ above, bad master.

 

I failed to mention in my original post that I did test the pedal in my driveway with the engine off, and indeed the pedal slowly goes to the floor when depressed.

I appreciate the responses to my problem, as I suspected it seems that the master cylinder is due for replacement.

 

Also Spike I see that you are located in Grand Rapids, Michigan. Whereabouts? I grew up near Leonard and Diamond.

 

I am in the SW side, by 54th St Meijer, about a mile away by a golf course.

 

It was indeed the master cylinder. I purchased a remanufactured OEM part, as opposed to a new aftermarket one. Brakes are working fine now.

On a confusing and unrelated note, my transfer case shifter that has been frozen for as long as I have owned the vehicle suddenly freed itself and began working as soon as I fixed the brakes.

 

Thanks for actually bringing the thread to a conclusion...drives me crazy that there are so many open-ended ones here.