85 K10 Brakes

[modhunt]

Okay so before my engine blew roughly a year ago my brakes worked fine fast forward to now and I have some issues
1. I put new rubber and metal lines on in the front while I was waiting for the engine
2. We got the truck running and went to bleed the brakes it would build pressure when the truck was off but would fall to the floor when it was turned on no brake pressure at all
3. Chalked it up to the bleeders on the caliper being stuck and being able to properly bleed them
4. put on new calipers bled the lines and same issue
5. I check all the front lines they arent leaking from anywhere and im getting fluid into the caliper

any help would be great

 

[frankin5]

You hook up vacuum to booster or is hydo-boost.

 

[modhunt]

You hook up vacuum to booster or is hydo-boost.

It’s vacuum could you elaborate where the line from the vacuum booster is to the pump or is into the back of the carb

Edit: I do have it hooked up

 

[frankin5]

when you push pedal with engine on is there any noise heard. It could be just air in the lines or proportion vale tripped. Is there vacuum at the booster with engine running, could be a leak in the booster.

 

[modhunt]

when you push pedal with engine on is there any noise heard. It could be just air in the lines or proportion vale tripped. Is there vacuum at the booster with engine running, could be a leak in the booster.

There is vacuum no air in the lines just re bled them and it was shooting fluid out like no tomorrow in a constant stream and I dont hear any noise with the engine on The fronts are getting fluid for sure and i pressed the button on the valve to double check

 

[Wes Harden]

sounds like there is a problem with your booster. Try disconnecting the vacuum hose, be sure to plug it, and start engine and see if problem is still there.

 

[modhunt]

sounds like there is a problem with your booster. Try disconnecting the vacuum hose, be sure to plug it, and start engine and see if problem is still there.

Ill try that tomorrow before i head to class I bench bled my master as well

if it is the booster I should just replace the master and booster at them same time while im at it right>?

 

[frankin5]

Did you bleed the rear lines since you had the master off? If the booster proves bad and they are an unknown old, I would replace both.

 

[modhunt]

Did you bleed the rear lines since you had the master off? If the booster proves bad and they are an unknown old, I would replace both.

Yeah I redid them after i put the booster back on. Can anyone recomend a really good booster price isnt that big of a deal I havent heard the best about like napas and autozones stuff

 

[Wes Harden]

if you have a nice firm pedal when w/o the booster. Your master is probably ok. New master cyl aren't terribly expensive, so would be your call. piece of mind is worth

 

[modhunt]

if you have a nice firm pedal when w/o the booster. Your master is probably ok. New master cyl aren't terribly expensive, so would be your call. piece of mind is worth

yeah when i pump it 2 or 3 times with out the engine on it builds and is pretty stiff

 

[Fordum]

Forget the booster. Your last post showed the problem.
Turn off the engine. Pump the pedal 4 or 5 times to be sure you have bled off all the vacuum. Let the pedal return all the way up. Wait a few seconds just for luck, then press the pedal down firmly until it stops.
Don't pump it. It should stop from 1/4 to a little over 1/2 way to the floor. And be nice and firm when it stops. If it stops but is spongy, you have air somewhere, either the master cylinder, a caliper, or back wheel cylinder or a line.
But, I suspect it will go all the way down or almost all the way. If so, stop, jack up the rear wheels and adjust the rear brakes until the shoes lightly touch the drums.
If that gives you a firm pedal in the correct range, then we can check the booster.
If it still goes all the way down, then its probably going to be the master. But just for fun, pump the pedal until you have it in the range mentioned. Then bear down on it fairly hard to see if it is spongy.
A very slight amount of give is OK and is due to the rubber lines and compressing brake friction material. Lots of give is air.
If its firm, then its most likely a bad master. Have someone push the pedal down slowly while you watch the fluid in the master. A slight amount of fluid jetting up as they begin is OK, but you will probably see the fluid moving during the entire stroke as it slips past the piston.
You MUST have a good hard pedal in the proper range with no booster first. The booster has no effect on the workings of the brake parts. It simply increases your normal pedal pressure.

 

[modhunt]

Did you bleed the rear lines since you had the master off? If the booster proves bad and they are an unknown old, I would replace both.

if you have a nice firm pedal when w/o the booster. Your master is probably ok. New master cyl aren't terribly expensive, so would be your call. piece of mind is worth

Forget the booster. Your last post showed the problem.
Turn off the engine. Pump the pedal 4 or 5 times to be sure you have bled off all the vacuum. Let the pedal return all the way up. Wait a few seconds just for luck, then press the pedal down firmly until it stops.
Don't pump it. It should stop from 1/4 to a little over 1/2 way to the floor. And be nice and firm when it stops. If it stops but is spongy, you have air somewhere, either the master cylinder, a caliper, or back wheel cylinder or a line.
But, I suspect it will go all the way down or almost all the way. If so, stop, jack up the rear wheels and adjust the rear brakes until the shoes lightly touch the drums.
If that gives you a firm pedal in the correct range, then we can check the booster.
If it still goes all the way down, then its probably going to be the master. But just for fun, pump the pedal until you have it in the range mentioned. Then bear down on it fairly hard to see if it is spongy.
A very slight amount of give is OK and is due to the rubber lines and compressing brake friction material. Lots of give is air.
If its firm, then its most likely a bad master. Have someone push the pedal down slowly while you watch the fluid in the master. A slight amount of fluid jetting up as they begin is OK, but you will probably see the fluid moving during the entire stroke as it slips past the piston.
You MUST have a good hard pedal in the proper range with no booster first. The booster has no effect on the workings of the brake parts. It simply increases your normal pedal pressure.

After all the help from you guys I got it fixed on my own with out having to call my mechanic buddy for help which I think is a good thing seeing as this is my first truck and my first real major learning experience to figure out how to do stuff on my own with some guidance.
He was there watching to make sure I did okay and to give me a final check because hes a family friend and he values my safety a lot and wouldn't let me move it till he gave me one final check over to make sure I had brakes and wouldn't get hurt. Hes a nice guy to take time out of his extremely busy week to come down and have a beer or 2 with me and just bs around while i try to fix it
Now onto what the issue was
As @Fordum said at the start of his post the rear shoes needed a lot of adjustment the reason I went into detail about my mechanic friend is he drove the truck when I got it and felt the brakes then He said he honestly didn't think I had any rear drum brakes the entire time the truck ran and drove now this fixed the issue a whole lot but not all the way
As me @Wes Harden and @frankin5 Where talking about the booster there is an issue with it which I thought there was a small issue with it from the start. It works but will definitely need replacing before I get my inspection and take it out and start driving it again under orders from my mechanic who will be doing the inspection. Its old and the seals and everything are starting to go in it

All in all you guys helped me fix one of the last major things to get the truck running now there is only 2 things left big thanks to you guys for taking time out of your day to reply and help me out