'93: Brakes: Sprong! noise, ABS light, pedal gets weird

[EurekaExplorer]

After extensive search, can't find a thread that describes what my '93 E. Bauer is doing.

Pressing brake pedal, there is a "sprong!" noise (actually sounds like something rotating and not meshing) and pedal is pushed back at me hard....sounds like coming from other side of firewall. Happens right after startup, first mile or so of driving. (at first only did this on sharp, low-speed turns, now happens first few stops). Then ABS light comes on and this *usually* disappears.

Following this, the brake pedal travels to the floor but normal pressure returns after one or two pumps. Goes through this cycle a couple of times, then brakes seem normal, but ABS light remains on.

Getting worse...pedal traveling to floor more frequently.

Now am having episodes of vehicle suddenly yanking to the left.

Is this all an ABS problem...the noise, the pedal being pushed back at me, the pedal traveling to the floor, the pulling to one side?

Master cylinder full, but fluid dark and dirty...can find no obvious leaks on my garage floor.

Also...noticing very low growly seemingly from left wheel starting about 35 mph...feel it more than hear it really.

Wondering if this is all related.
Thanks.

 

[BP_93explorer]

the ABS kinda sux on these vehicles. the pushing back thing i feel at times. i hear a grinding type noise with it. mine went away for the most part with new pads although it still does it at weird times (like before the brakes have warmed up). hopefully someone here will know exactly what your problem is because i've never had the pedal go to the floor before. i'd take it straight to a shop if that happened to me.

 

[EurekaExplorer]

Thanks for the input. Have been researching the ABS problem on this site the past few days and have learned a lot. Trying to figure out if the pedal going to the floor is definitely a faulty master cylinder or if a problem, such as air, with the ABS HU could be causing it.

Will take it to a shop if necessary, but I want to diagnose the problem myself first to the best of my ability.

Another thing I am not clear on...if I replace the master cylinder myself, is there a way to stop air from entering the ABS HU, or is there no way to prevent it?

This forum is a very valuable resource. Thank you.