slantflat

Hi everyone.

This is your run of the mill 90 Beauville 350 automatic. A buck forty on the clock. Rear cylinder had a leak, master went dry, now with new cylinder and master full the rear brakes won't bleed. Classic symptoms of the proportioning valve meter sliding to the rear and blocking off the rear brake lines.

Here's my dilemma. Watched several YouTube videos where they say all Chevy truck prop valves are the same. They are not. What I have are two blocks, inboard has lines coming from master, a couple lines going to wheels and a couple lines going to the second block. Outboard block has a couple lines going to wheels.

Question. Which block has the meter, and how do I reset it? Inboard block has plugs on both ends, outboard block has a line going into the rear and a plug in the front. And now that it's been tripped, will it do it again easily, such as when I'm bleeding the rear brakes?

Thanks everyone.

Beau Oszman

Not sure, I think I got what you're talking about. Sounds like your valve went to block the rear at some point and got stuck in that position. Will probably need to be replaced. There are videos on how to check/test valve. Good practice most don't bother with when dealing with that valve is to use a tool (I've only seen it used once personally) to lock valve in place during bleed process. If your valve is still working properly, find something that'll work to lock valve in place then bleed. Aside from that, the system should go: Master-proportional valve-ABS solenoid (if applicable)-brake cylinders. Never heard of a system with 2 valves after master. I don't claim to know everything though.

cablesplicer

I am not sure i understand what your trying to say but if the second block is mounted on the rear axel with a arm attachment that changes the fluid going to rear breaks according to how much load you are carring and shouldn't hinder bleeding . Biggest trouble bleeding rears on my 87 g30 i had was from having an older master cyc. That when pedel pushed to the floor caused it to stick from the difference in the bores ware [between where it usualy stopped and where it had never has to]. I hope it helps. Maybe some photo's could help me understand your description. Good luck and if you get it fixed please tell us how the trouble was caused/fixed.

slantflat

No both blocks are mounted next to each other, left side of engine, right under the master cylinder. I'm not close to the van now so I'll get a picture when I get home.

slantflat

Okay I'm gonna see if I can get this picture to attach. Sorry if this is too big, my computer(or the operator) isn't good at this sort of stuff.




This picture is taken standing at the grille looking toward the motor. Driver's side is on the right. What am I looking at here?

Beau Oszman

One of those is the proportioning valve and the other is... I'm not sure. Unless someone else knows right off, the research begins. I like learning new things.

Beau Oszman

Alright, fairly certain the left side of the picture is a proportioning valve.

Similar to this one.

Uses a tool like this.
Still trying to figure out the other block. May be metering block for rear, though that should be built into the valve starting mid 70's models. Still looking for an answer for that one.

Beau Oszman

Had a feeling I poured over the info for my '93 before. Chilton refers to the proportional valve as a combination valve instead.


Step 5 deals with proper bleeding procedure.
Looks like the other block quit possibly is the isolation/dump valve.

#'s 10&7