Okay so i went through my 83 k5 blazer and replaced the two front side brake lines, front to brake calipers, the two rear wheel cylinders, and rear brake shoes, i also had to replace one brake line on the driver side rear. And i keep bleeding the system but the pedal just keeps feeling squishy and doesnt even start braking till its close to the floor. Can someone tell me what im doin wrong?
CK5
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brake question.
- Thread starter K5Titan83
- Start date
what process have you used to bleed the brakes.
Im using the process from the chilton manual. Start at the right rear and hook a tube to the bleeder and run it into a container of brake fluid. Have my buddy pump the brakes 3 times slowly and hold it. I release the pressure untill i see the fluid stop and i close it.
I repeat that 3-4 times a tire going from right rear, left rear, right front, and left front
If there is still air in the system,the pedal should pump up higher after several strokes...after you let off the pedal,if it goes close to the floor next time you apply the brakes and it remains low,unless you pump it several times ,chances are the rear shoes are not adjusted close enough to the drums...
After adjusting the rear shoes,try bleeding it again..the pedal should remain high after the first application,not gain height after several pumps,if its bled completely..
I had a rear rubber brake hose plug up solid on my van,it drove me nuts for 3 days,I had replaced the rear steel lines and even tried a rebuilt master cylinder,and could not get ANY pedal unless I pumped it like 15 times--then it would go right to the floor after I released pressure and went to pump the pedal again...found out the plugged hose was not letting ANY fluid pass to the rear wheel cylinders,so I couldn't bleed the new steel line running from the front of the van to the rear hose...once I put a good hose on it,I bled it in 5 minutes...
A quick way to test if the master cylinder is leaking internally is to plug off the two ports with suitable fittings--the pedal will be rock hard and not "leak down" with light pressure if the seals are still OK--I did this to make sure my "new" master was working OK,and it was...and I bet the original was too!--and I replaced it for nothing..
..but it was 1981 vintage with almost 190K on it,and only costed 20 bucks,so it was worth replacing anyway..
After adjusting the rear shoes,try bleeding it again..the pedal should remain high after the first application,not gain height after several pumps,if its bled completely..
I had a rear rubber brake hose plug up solid on my van,it drove me nuts for 3 days,I had replaced the rear steel lines and even tried a rebuilt master cylinder,and could not get ANY pedal unless I pumped it like 15 times--then it would go right to the floor after I released pressure and went to pump the pedal again...found out the plugged hose was not letting ANY fluid pass to the rear wheel cylinders,so I couldn't bleed the new steel line running from the front of the van to the rear hose...once I put a good hose on it,I bled it in 5 minutes...
A quick way to test if the master cylinder is leaking internally is to plug off the two ports with suitable fittings--the pedal will be rock hard and not "leak down" with light pressure if the seals are still OK--I did this to make sure my "new" master was working OK,and it was...and I bet the original was too!--and I replaced it for nothing..
..but it was 1981 vintage with almost 190K on it,and only costed 20 bucks,so it was worth replacing anyway..
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Okay. Well i just checked it. With the truck off. I can pump the pedal and it doesnt go all the way to the floor. It seems really squishy but its pretty even pumping. Nothing is pumping up. So that means i need to adjust the rear dums?
But if the vehicle is running it does what you said, it pumps up harder, but it i let off then push it again it goes to the floor. So yeah, the rear drums need adjusting. Do i need to take the drums off again? My dad said spinning them backwards gets them adjusted? Is that right?
rear drums are 'supposed' to be self adjusting by backing up and hitting the brakes - they're supposed to hit a star adjuster inside.
However, they don't always work properly. See if you have a plug in the bottom of the backing plate - should expose a slot. Use a flathead screwdriver or 2 to manually spin the star adjuster.
Here's a pic of what you're trying to hit. (not my pic)
http://s16.photobucket.com/user/LaneJ/media/IMG_4349.jpg.html
However, they don't always work properly. See if you have a plug in the bottom of the backing plate - should expose a slot. Use a flathead screwdriver or 2 to manually spin the star adjuster.
Here's a pic of what you're trying to hit. (not my pic)
http://s16.photobucket.com/user/LaneJ/media/IMG_4349.jpg.html
Well I just took the drums off and adjusted them to the point where the shoes are just barely rubbing against the drums and I bled again (which doesn't appear to have any air in the lines anymore at all), and the same thing. the pedal is just soft and you press it and it slowly falls to the floor, same thing while its running. and at a low speed it feels more firm compared to a high speed just after acceleration where it feels very soft. I'm not sure what to do next here. could the brake booster or master cylinder be bad?
Could be, but you would have had the same issue before all the changes.
When i bleed, i leave the bleeder open long after first sight of fluid, but just before the pedal hits the floor. On the rears, I've been known to open the bleeder and walk away, fill the master cylinder, walk back and watch it weep before closing it. Would probably do the same on the front. Then bleed them again.
When i bleed, i leave the bleeder open long after first sight of fluid, but just before the pedal hits the floor. On the rears, I've been known to open the bleeder and walk away, fill the master cylinder, walk back and watch it weep before closing it. Would probably do the same on the front. Then bleed them again.
If you can pump it up and when you hold it, it slowly goes to the floor, that's an internal leak in the master cylinder.
Brake booster just pushes on the input to the MC, it can't affect anything aside from how much force winds up on that piston. It can amplify problems, but it can't make hydraulic pressure disappear. If you have the same problem when running and when not, you aren't looking at a booster issue.
If you are able to activate the brakes (and safely stop), and the pressure bleeds off while you're pressing on it, you are losing fluid from the hydraulic circuit. If you don't find any external leaks, you may well be dealing with a leak inside the MC (fluid leaking back to the reservoir, so you don't see any puddles). If this is the case, replacing or rebuilding the MC should solve the problem. If the pedal is just soft all the time (and you can't make the wheels lock up, even when you stomp on it several times rapidly), the cause is less certain. Could be MC, air in the lines, or any of the other causes already mentioned.
I assume this problem started after you installed all the new parts?
It's possible that your MC gave out right at that moment, but it's not very likely. I'd keep checking for air bubbles & leaks.
okay. well I talked to a mechanic friend and he told me to try something, said the proportioning valve might not be letting all the air out or something I don't remember exactly, and to try backing up pretty quick and slamming the pedal. so I did and it finally kinda locked em up and I slid on the gravel and after that I didn't have brakes at all. so I figured it pushed some air out. so I went to bleed them and, the right rear pushed a lot of fluid and water the first time, after that nothing, and the left rear didn't bleed at all. I haven't even tried the front yet. asked my mechanic friend and he said it sounds like the master cylinder, so I guess tomorrow il try that.
I started all this because it was lurching bad to the left when I pressed the brakes, it stopped good just lurched left real bad so when I got into it I realized no one has ever done anything to the brake system on this truck. I know I haven't for the past 6 years iv owned it. so I started going through and replacing what it needed, so go figure everything would start coming apart. just my luck haha
so we will see what tomorrow brings
I started all this because it was lurching bad to the left when I pressed the brakes, it stopped good just lurched left real bad so when I got into it I realized no one has ever done anything to the brake system on this truck. I know I haven't for the past 6 years iv owned it. so I started going through and replacing what it needed, so go figure everything would start coming apart. just my luck haha
so we will see what tomorrow bringsI just remembered and I don't know if this will tell you anything or not but I added brake fluid to the reservoir before I started any bleeding, well in my carelessness I left the lid off of the reservoir and it shot fluid up damn near to the hood while it was open, this is probably normal idk but I figured id let ya know, maybe that means something 
yeah, you want to set the lid back on when pumping the brakes. And that brake fluid will quickly strip paint and melt a lot of plastics, be sure it's cleaned up.
I agree that you don't have all the air out yet, but I'm not yet convinced that you're looking at an MC problem. You should never have had water inside your brake lines. Assuming that you didn't add water into the reservoir while you were bleeding, that water is old fluid. And if you haven't gotten all the old fluid out, there's a good chance that air bubbles are still trapped in the high spots.
Backing up and slamming the brakes is how you automatically adjust the rear brake shoes (like you did manually). If they are loose, the shoes will rotate slightly and the little lever will tighten the adjuster by one click each time you lock the rear up. If they are tight, they will not be able to rotate and they will stay where they are. Great idea when the parts are new and shiny, less useful when the parts are rust or broken. When you are done with the bleeding, you may wish to do this a few times to dial in the shoes. But I wouldn't think that would have much affect on bleeding.
Sorry i typed it wrong. Idk why i said water. I meant a lot of fluid and air came out. My bad. Well if it isnt a MC problem what could it be? Should i just keep bleeding the system and see what happens? I dont need the truck so it can sit and i can keep trying to bleed it every so often.
So before i tried the reverse thing and the brakes totally stopped working i drove it and i could get it to stop, but it felt like the pressure was bleeding off of it. So i could stop effeciently but if i were to need to stop in an emergency it wouldnt do it. Pedal was to soft. But like i said that was before i did the reverse thing because now i have no brakes, it wont even pump up now.
