Bled the Brakes and Now I Have None

[The Baron]

I have a 1984 M1009. A week ago I decided to switch out my brake pads. I noticed for the front brakes the caliper never fully released. I then proceeded to change the calipers. Once I did that there was no difference, the calipers were still sticking. Some employee at Autozone said that it could be my brake fluid was no longer good. Sure enough I remembered that the brake fluid coming out of the Blazer was black ( I'm not sure why this didn't concern me at the time), so today I started flushing my brakes with new fluid. Half way through the job I completely lost pressure on my brake pedal. Now when I try to bleed them the fluid only trickles out. I think I may have accidentally let the smaller compartment of the reservoir run dry or almost dry. If that is the problem how can I fix it? Also how can I tell if it's the master cylinder that went bad? Thanks for any help and sorry for the dumb question I'm still a novice at this.

 

[The Baron]

Also, the brake light ( which usually comes on for the parking brake) came on. Also we were pushing the brake all the way down when bleeding, which from what I just read your not supposed to do.

 

[AECS]

Just keep at it. You have a big air pocket that will have to come out, it will take a while. Happened to me once, took over an hour to get them to pump up tight.

 

[The Baron]

Should I just bleed it normally or bench bleed the master, Also Do you think it's the fluid that's making the calipers not release all the way?

 

[3rdaavbn]

Always bench bleed a new master.

 

[The Baron]

I forgot to say that there was a lot of time between when the compartment running out of fluid and the brakes dying. I did top it off when I noticed. If the brakes lost pressure because of running out of fluid during the bleeding would the brakes stop working right then and there?

 

[rsh4364]

I bought a cheap vac.pump as I normally have no help around,works great.Also easy to see when you have good clean dot 5 coming out.

 

[dependable]

It is common for the rubber flex lines of this age to internally collapse even though they look fine from the outside. Suggest replacing all 3 if they are original.

The fluid probably is not the problem unless you mixed DOT 3 (alcohol based) with DOT 5 (silicone based), in that case you need to completely flush system. Lots of threads here on that topic.

 

[Mainsail]

Just keep at it. You have a big air pocket that will have to come out, it will take a while. Happened to me once, took over an hour to get them to pump up tight.

I bought a cheap vac.pump as I normally have no help around,works great.Also easy to see when you have good clean dot 5 coming out.

I let some air in the last time I was bleeding the brakes. Once you get a big air pocket in there it compresses and your pedal pushing becomes significantly less effective. My wife's leg was getting tired. I pulled the vacuum pump set-up out of the garage and plugged it in. Positioned the wife at the reservoir with the bottle of DOT-5 and turned on the vacuum- it took just a few seconds to pull all the air and the clean fluid through.

 

[MarcusOReallyus]

Don't do anything else until you have verified what type of fluid was in it and what type of fluid you added.

 

[The Baron]

I always put dot three into it. But what I was wondering is there was a five minute period between the point where I may or not have let air into the system and the point where the pedal stopped working, if there was air in it wouldn't the pedal have stopped working immediately?

 

[dependable]

Your combination valve may be stuck. That controls light and also stops flow to fluid low (ie leaking) part of system (front or back) so the other half still works. If you did have DOT 5 in there at first, that might explain it sticking, as mixing the two types of fluid can really gum things up. And cause calipers to seize.

The flex line internal failure I mentioned previously can cause calipers to seem seized up tight. The failure can happen pretty fast and it can lock it right up, taking hours to bleed back though constriction.

Also confirm you did not spring a leak in rear brake system while bleeding. A rusty line or wheel cylinder failure while pumping them up is common. The small reservore in master cylinder is for the rear brakes.

Might be time to go right though them, all getting old, fluids may be mixed, multiple problems.

 

[MarcusOReallyus]

I always put dot three into it.

Okay, you put DOT3 into it.

What was in it before you started putting DOT3 in it?


Here's what we know for sure:

1. It served in the military with DOT5 in it.
2. You have put DOT3 in it.
3. 5 and 3 do not play nicely together.

Unless somebody before you purged the system and cleaned out all the DOT5, you now have a major problem. You don't know. You are talking about brakes and you don't know.


I really think you need to flush the whole system thoroughly.

 

[Recovry4x4]

Being a novice at this brings up some concerns. When bleeding brakes with a master cylinder that has been in service for a while, there are some precautions that must be followed. Pumping the pedal to the floor often does more damage. You are forcing seals into an area of the bore that may be contaminated with rust. In doing so you can damage the seals. If it were my truck and considering all the facts we have, I would replace the master and do a complete flush. A power bleeder would be a huge help about now.

 

[the skull]

^^^yes.^^^
I flushed mine out after replacing both rear lines, I used the Harbor Freight
brake sucker. But they were spongy afterwards, we manually bled them at
all 4 corners. THAT fixed it. I really believe in a manual bleed, there are
air pockets all over that don't respond to a siphon gun. Also, try the power
bleeder with the brake pedal part way down. DOT 3 is cheap. I priced the
master cylinder, like $50? I bought one but took it back, it stops better
than I would have expected from a 3 ton beast. I have an 81 2wd C20 with a
vacuum booster, I like the cucv brakes better.

 

[The Baron]

I see no visible leaks and the flex lines are about a 2 years old. Could they go bad that quickly? The mechanic who originally did the brake job used dot 3 and I guess I just assumed that was the right stuff. That explains why the fluid looked so bad, Looks like I'm going to be flushing the system. So for this you just run deprotonated alcohol through the system? Also once I flush it can I start using dot 3 or do I have to use dot 5. I read something about the rubbers in the systems being different

 

[dependable]

If the flex lines are only 2 years old, I would think they would be good, unless some really cheep import parts(who knows, these days). Take flex line off and test with air, it should be unobstructed.

The black fluid part makes me wonder if some other (petroleum based) contamination got in there at some point, that could wreck flex lines and seals.

Neither the DOT 3 or 5 should attack the rubber or seals if these are normal brake components. They just should not be mixed.

If you get all the DOT 5 out, you can used DOT 3 no problem.

 

[MarcusOReallyus]

You might want to do more reading on this. There's a difference of opinion out there on the correct procedure.

http://www.type2.com/library/brakes/dot5.htm

http://www.garagejournal.com/forum/showthread.php?t=61389

https://duckduckgo.com/?q=how+to+flush+dot5