I've got an 88 Pickup that I bought 1 year ago. In the few repair records that I did get, I noticed that it had recently gotten a new master cylinder. Over the past six months, I've been getting a "binding" in the brake pedal. It used to be very intermittent, now it is just about every time I use the brakes. Basically, if I press the brakes lightly, no problem. If I press the brakes harder, the pedal travels, then stops traveling (binding), then continues its travel with a squeaky thunk. The stopping of the brakes is always consistent with the position of the pedal, but it is impossible to smoothly press the pedal as it always binds. So, is it likely that the new master cylinder is the problem, or is it more likely the problem is in the pedal linkage? How would you go about troubleshooting this one? I'm just looking for some quick advice to get me started on the right track (hopefully). Thanks!

Sounds kind of like a bad master cylinder. Any leaks around the back of the master? Hows the fluid level?

Thanks for answering. No leaks that I can see. Fluid level is near Max and has not gone down.

If its not the MC, check under the dash at the bracket that the pedals hang from, it could be cracking. Common Toyota problem!!!!

may sound stupid but are your rear brakes adjusted right. you could just be bindig on the the master cyclinder because you can push it any more. they only push in about a inch and a half

Thanks, I'll check that.

Well, I don't *think* so, but I'm not sure. I'd say the binding occurs at between 40-50% of full braking. So there is quite a bit more travel that produces more braking (stopping). Does that add or detract from your theory?

So, I replaced the master cylinder. I started bleeding the system. When I bleed the front two brakes and the load sensing proportioning and by-pass valve, I have no problems. But BOTH of the back two brakes aren't producing any pressure when my helper presses on the brake pedal. Each stroke from the brake pedal is producing about 1/2" of fluid visible in the vinyl tubing I have attached to the bleed nipple. And it comes out S L O W . . .

When all the bleed screws are closed, the brake pedal goes to the floor with about equivalent effort as the clutch pedal.

Is it possible that I have so much air in the lines that I have a big air bubble that is compressing each time my helper presses the pedal? If this is the case, would a power bleed help?

Any other ideas?

when you bleed the brakes if you push to the flow you will bottom out the lspv what worked for me is have someone push on the brakes and tap on the lspv with a hammer you should here a tiny clunk noise. in most cases it can be fixed that way or crakc a bleeder on the rear wheel and it should release. does the front of the truck dive when you brake

Yeah, the more I got to thinking about it, the more convinced I becamse that something must be wrong with the LPSV.

So, you're saying to give it some tabls while someone is pressing the brake pedal. So something is bound up, and this should free it?

I have not taken the truck out of the driveway, so I'm not sure whether the front is diving or not. I assume that you're asking this to determine whether the front brakes are doing all the braking?

Thanks for your help! I'll give it a try (hopefully tomorrow), and let you know how it turns out.