Proportioning valve problem?

[MikeB]

Originally Posted by PbFut

Mike, Good to see you got it working. Did you figure out the actual fail point on the valve you replaced?

No. But I did pull out the valve and spring, and another piece fell out. The only rust I see is on the threads and o-ring. There's a sleeve inside the casting that also looks OK, but not great.

The aftermarket brass valve is working OK and not leaking (yet). It came with a later model switch and pigtail that I'll use. I'm pretty disappointed that the new OE switch replacement failed so soon.

I have to make a confession here. I'm actually wondering if there was any problem at all, other that the switch being too sensitive. When I started to bleed the rear brakes yesterday, I initially had the same problem -- low flow out of the bleeder screw again. Oh, no!

But here was the problem: It's really hard to get much of a turn on a box end wrench with the bleeder's location in the wheel cylinder casting. So I was able to insert the wrench in a way to get maybe another 45 degrees on the turn, and lo and behold, fluid streamed out! Really strange because I have bled brakes dozens of times over the years w/o screwing up like this.

Oh, well. I can tell myself 1) I learned something, 2) I have new fluid end-to-end, and 3) I'll end up with a rebuilt OEM combination valve!

It was also a good day because we fixed a couple brake problems with my buddy's new-to-him 99 Silverado 1500. One of the rear caliper pistons was stuck (!) and the parking brake adjustment was too tight. No bleeding problems, though.