I have a '90 3/4 ton 4x4 Sub. I had a problem w/the brakes, the pedal felt funny. It would go down part way, easy, and then get harder. The brake light would come on when it did that. Then, when I pumped it, it would pump up and get hard (like normal) and the light would go out.

I figured that it was a master cylinder. So, I got one from Napa and put it on. Initially, it bled up just fine. I was flushing out the fluid by having my daughter step on the pedal and then letting the fluid out. I was getting rid of the black fluid.

I did the fronts and went to the passenger's rear wheel (yeah, I know that is supposed to be the 1st one done, but I was standing over the driver's side front, the wheel was turned and I could just about see the bleeder and it was calling to me). I did it about half way, topped off the fluid, went to the other side and did it. It took about 3 pumps, and the fluid came out clear....odd the other side had about 10 pumps and it was still dirty. I don't remember the exact sequence, but I figured that there was plenty of fluid in there....so I went back to the other side in the rear and about 3 pumps later, it stopped ejaculating out....OOOOps, out of fluid.

Now, I just used up a quart of BF. So, I root around in the shop and find some more. This bottle is old, open and when I put it in, I immediately notice that it is clear, but amber colored. Well not immediately, as I'm about half way filled up when I notice. It smells like BF and it came from a Dot3 bottle.

The MC bled just fine, then I went to the same wheel. I got the dirty fluid out, in a few more tries. But, it no longer ejaculates out like before...still no trace of air.

So, I drive it, and it acts like before the new MC, and now the brake light is on. The fronts lock up, on gravel and it doesn't seem like the rears are working at all.

I am going to get ride of the BF and put some new stuff in. Any other ideas?

 

Well, the matter is resolved. I scooped out the brake fluid w/a taco-sauce cup, and then got the rest w/a paper towel. Then, I started flushing the system. As soon as I re=bled the MC, I could tell an immediate difference in the ejaculation/stream. I used a full 12 oz bottle of BF.

I don't know if the brakes are working like they should, but the rears lock up on a gravel road, and also across the street from my house on asphault (w/a bunch of pebbles on it, that you can't see). The brake light also went out.