Yes I tested the booster.
I took two 6 in brake lines and bent them into an "S" and pounded them flat with a hammer. Then I hooked them up to the master cyl.
Next I pumped the brakes a few times, have pedal.
Then I started the truck, pumped brakes, have pedal.

So the master and booster both worked.

Then I took off the proportioning valve, looked at the end of it where the stem was. Tapped it in with a hammer and pulled it back out with vise grips.
Felt really stiff and not free moving, so I purchased a new one online.

I'll post after I get the part and if it works.

( PS Im pretty sure this is the issue, because when bleeding the front brakes very little fluid was flowing when I was bleeding where as the rear bled perfectly. )

 

I hate this damn truck....

I bought that proportioning valve and put it in tonight, tried to bleed the brakes, NOTHING!!!

So I'm back in my original situation with no friggin brakes.

To the shop this heap goes...

(brake pressure until I start the truck, then the pedal goes to the floor. I get very min brakes at the end of the pedal)

 

The only thing that changes with the brakes when you start the truck is that the vacuum booster kicks in. This would suggest to me that it is at least part of the problem.

 

Hi,

How did you test your booster?

Usually when they fail, the pedal will be super hard. I would check the boosters check valve, as well as for vacuum leaks going to the booster.

It sounds like you have zero power assist...and you are 100% positive you have no brake line leaks right?

 

OK so its lunch time and I took the truck to the shop while on break.

He calls me after a bit and says that he too can not get the brakes to bleed, low pressure to the front brakes. ( same issue I was having )

He says its a bad master cylinder and wants to know if he can charge me and put in a new one. I tell him that the master in there is already brand new but go ahead. ( I figure at this point what ever, I'll return the one I bought )

So he is doing that right now, I'll let you know the verdict....

PS

So you all know what I have done thus far. I have replaced the master cyl, every brake line/hose , slave cyl's , proportioning valve, calipers , shoes, pads, and springs. EVERYTHING.

I bleed in the correct order, BR , BL, FR, FL.

I even "tested" the master by plugging the two brake line ports with caps.

When I "tested" the master with the caps, I had pedal like I should. With and without the truck running.

When I put the brake lines back on after removing the caps and re bleed the lines, I get pedal without the truck running, but NO pedal ( well very little ) when it is running.

Also, when bleeding the lines it appears that the front calipers bleed slowly while the rear ones bleed quickly. ( perhaps a pressure issue? )

As for testing the booster, it SEEMS to work fine. Hard to press pedal when not running, easy to press when running. ( too easy, lol )

So I will post what the shop says when I hear from them.

THANKS SO FAR!!!

 

FIXED!!!!!!!!!!!!!!!!

SO it was a bad master cylinder.

I had some not so kind words for Advance Auto when I found out that for the past week under the hood I was fighting a bad "new" master cyl.
Ohh well....

Thanks guys!

 

Don't you hate when that happens. It is a 50 mile trip every time I go for parts. Nothing pisses me off more when I am working on a vehicle than to get replacement parts that are bad. One thing I do to help prevent this is I never buy rebuilt if I can buy new parts instead.

 

Hi,
Im glad it fixed! But i hope you didnt yel at the Parts Sellers.....they dont make the parts, just sell them. I would give the company that made that product wether its new or remanned a call.

 

Ouch! You suffered a lot from a defective part. Lots of time and money for nothing.

A mechanic friend of mine tells me that the failure rate of new parts is very high these days. He blames it on them being made in China.

We used to buy kits and rebuild our own wheel and master cylinders.

 

Hi,

I wouldnt put all the blame on defective parts these days down to it been a problem from China. Alot of American parts are JUNK also. And most aftermarket rebuild kits for master cylinders, calipers and brake cylinders come from Mexico