Ok...some of you have seen the slow but sure complete overhaul of the brakes on my beloved sin bin. Today I replaced the master cylinder. I don't have a bench and vise to do a normal bench bleed on it, so I slapped it in the van and bled it with the pedal before hooking the lines to it....so far so good...

After hooking up the lines I jack the van up and start to bleed the whole system with my trusty one man bleeder kit. I go around the truck in standard fashion; right rear, left rear, right front, left front. All kinds of icky stuff came out and I ran new fluid through until it bled crystal clear.

Now for the moment of truth...I start it up and test the pedal....not bad. Idrive it slowly around the neighborhood, and the brakes are as bad as before. There is only about 1 or 2 inches of actual engagement at the bottom of the pedal's travel. The drums, shoes, rotors, and pads are new. There are no leaks and the wheel cylinders and calipers are dry.

Does anyone have an idea of where to go next? I don't think this thing has a proportioning valve that could blow out. Could it be I need to adjust the pushrod longer so it has more stroke? HELLLLP!! I need to take this thing on an 800 mile band road trip in 2 weeks!

 

Don't adjust the pushrod too much, 'cause you need some free-play in it, or the brakes will bind.

You sure there is no proportioniong valve?
Seems to me, years ago, I had a similar problem and had to push the pin on the valve in when bleeding the brakes. It did the trick.
Did you check the shop manual?

 

I have not had good luck with one man bleeders, they always seem to leak just enough air to make the brakes soft. I think the speed bleeders might be a better idea.

 

No manual handy....but I haven't been able to find a part number for a prop valve anywhere. As much of my weekend time as this has been eating up, I might just take it into a shop and see what they say.

 

I don't know much about the van setups, but my trucks proportioning valve is just below the master cylinder mounted to the frame. On mine the brake lines from the master cylinder connect directly to the proportioning valve. Just follow the lines down from the master cylinder and they should endup at ther proportioning valve before they are sent off to the front and rear brakes.

 

Go to http://www.autozone.com and on the left click on "Repairs".
Follow the links and see if there is a manual for your van.

Edit: I just checked, it is not listed.

 

You do need to open the proportioning valve to bleed system properly. Pull the pin out and hold it out by slipping a "c" clip or cotter pin behind it, or use small locking grip pliers.

(To bleed master cylinder, you need to make a short adapter line bent to feed back into reservoir; then bleed per cylinder directions - assume you did this.)

Buy, borrow, or "browse" a Haynes manual for more info -
you may also have a vacuum booster problem.

 

It's been bled down well and is much better. I just had to do the 2 man bleed...the one man tools/kits are ok in a pinch, but the old fashioned way is better. Now, if I could just get the self adjusters on the rear to work properly......

 

The main problem with doing it THAT way is that the MC sits at an angle that is all wrong for properly bleeding it. All too often air remains in a kind of "nose pocket" and doesn't quite get bled out. Seems to me by your description this is what has happened, and ESPECIALLY so because of the one-man bleeder, which pulls fluid thru the cylinder but doesn't necessarily void the air pockets. That's also why you got better results (altho not perfect) with the two-man system.

Self-adjusters are for mainaining an adjustment. you have to set them up properly adjusted FIRST. annoying, I know, but necessary. If you have access to a caliper, adjust them that way first. also make sure all your springs have plenty of life left in them. I new spring kit is really only about $17/ side.

 

I think the last spring kits I bought were less than $10 a side. The determining factor in brake pedal travel is ultimately the rear brakes. If the shoes are good but the drums are shot or vise-versa you can get a lot of travel in the pedal. There SHOULD be a proportioning valve on the frame almost directly below the MC IIRC. I've seen on there on almost all my ford vans.