Bleeding Brakes?
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Freshman User
Joined: Sep 2005
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From: Enfield CT
Bleeding Brakes?
Anyone ever gravity bleed brakes? I just did this last weekend, and it worked amazingly well. I just cracked each bleeder open, and let each one drip until it no more air bubbles came out. I didn't think it would work at first, but I was alone, and it did.
Any thoughts?
Any thoughts?
Senior User
Joined: Mar 2005
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I often use the 'one man brake bleeder' things you can buy. It's just a peice of tubing with a one way valve in it. They seem to work very well.. just open up the bleeder, attach the thing, put a bucket under there and go pump the brakes till your hearts content. Use it for flushing the fluid too.
Postmaster
Joined: Jul 2005
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From: Abilene, Texas
I have gravity bleed brakes alot. It almost always works. There has been a few times like maybey once or twice that it didnt work. I do alot of brake job too. So to me gravity bleeding is the best option. I dont like using the one man jobbers, because I never can get them to work for. I guess I dont do something right. I never tried that one with the tube though. The only ones I have used are the ball one that attaches to the master Cylinder. anyways I like gravity bleeding brakes when I dont have anyone there to pump up the brakes.
Scotty
Scotty
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You possibly won't get a true bleed as the piston have travel their full distance.
The fluid is only being bled with the distance the pistons move at time of bleeding.
If a Rear wheel cyl piston becomes freed up the fluid leaves the M/C and sucks air.
The system will have to be re-bled.
Maybe I'm tired and don't make sense...it's happened before
Also, the pin on the 79 PV has to be pulled to bleed the fronts
The fluid is only being bled with the distance the pistons move at time of bleeding.
If a Rear wheel cyl piston becomes freed up the fluid leaves the M/C and sucks air.
The system will have to be re-bled.
Maybe I'm tired and don't make sense...it's happened before
Also, the pin on the 79 PV has to be pulled to bleed the fronts
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Freshman User
Joined: Sep 2005
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From: Enfield CT
In this case I had brand new calipers, because my old ones were shot, the pistons would not retract back in.
I too do not like the one man check ball bleeders; I have never had one work well.
I was just really surprised gravity bleeding would work, I stumbled upon it purely by accident and since, I have talked to a couple other people that had done it. In this case I was not too sure how the proportioning valve would play with this, I didn't have it pulled out like the book says, and they gravity blead fine, but when I did pull it out, the fluid stopped dripping, so I just left it in its neutral state.
I too do not like the one man check ball bleeders; I have never had one work well.
I was just really surprised gravity bleeding would work, I stumbled upon it purely by accident and since, I have talked to a couple other people that had done it. In this case I was not too sure how the proportioning valve would play with this, I didn't have it pulled out like the book says, and they gravity blead fine, but when I did pull it out, the fluid stopped dripping, so I just left it in its neutral state.
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Elder User
Joined: Aug 2002
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From: CA
As long as your Brake warning light is not on, you can leave the pin in, as both sides of the system are open and of equal pressure (being 0) while gravity bleeding, and the pin won't effect this. Don't worry about the caliper or cylinder pistons siezing if the old fluid is relatively clean (not sure what mil1ion meant here), but keep an eye on the master cylinder so it doesn't run dry! While I prefer the two person method, I have gravity bled all my vehicles and it's always worked great.
Last edited by Polkat; Oct 18, 2005 at 04:03 PM.
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Thread Starter
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Freshman User
Joined: Sep 2005
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From: Enfield CT
Brake warning light? What’s that? Seriously though, where did / does the brake warning light connect to, and what was its purpose, and what models / years did it come on? I know I don't have one that works, if I even have one at all.
I was watching the MC to make sure it didn’t run dry. I was thinking about, just draining the system completely and putting all new fluid in too, the fluid in the MC is pretty nasty looking.
I was watching the MC to make sure it didn’t run dry. I was thinking about, just draining the system completely and putting all new fluid in too, the fluid in the MC is pretty nasty looking.
Elder User
Joined: Aug 2002
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From: CA
I agree that pressure bleeding is the best....for those that have the extra $$$. For those that don't, this technique works fine. However, if your old fluid is a mess as you say, then definately consider what 460me brought up if you can afford it. The brake warning light is used on a lot of vehicles that have front disk brakes. There is a brake fluid controlled switch in the proportioning valve. The front and rear brakes act as seperate systems, and should a leak or other flaw develop in one of the systems, the difference in pressure between the systems (when the brakes are applied) will force the switch to one side or the other (depending on which system side is bad), which turns the warning light on. You can tell if this has happened (say if the warning light has burned out) as the pin in the valve will be out. The light is on the dash, usually in the speedometer area, and comes on (with the oil light if you have one) when the ignition is first turned on as a test.
Senior User
Joined: Mar 2005
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Where is the proportioning valve on our trucks (mine is a 79 CC 4x4 if it matters)? I have a problem with my brakes where it takes quite a while to get them to apply sometimes. I am wondering if maybe there's something wrong with the rear brakes?
My understanding is that the proportioning valve ends up dumping fluid into the rear brakes until they apply and then the front starts to apply.
My problem is.. if I stomp on the brake, it takes a good 1/4 of a second or so to get it to start applying. It's hard to push and it's got to travel a ways before it starts to engage. I'm guessing that's not normal but I really don't know as I have nothing to compare it with.
Anyone have any ideas?
My understanding is that the proportioning valve ends up dumping fluid into the rear brakes until they apply and then the front starts to apply.
My problem is.. if I stomp on the brake, it takes a good 1/4 of a second or so to get it to start applying. It's hard to push and it's got to travel a ways before it starts to engage. I'm guessing that's not normal but I really don't know as I have nothing to compare it with
.Anyone have any ideas?
Elder User
Joined: Aug 2002
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From: CA
On the early 70's trucks the valve is on the frame rail, not too far under the master cylinder and back a bit. It has four lines going into it. Since the calipers take considerably more fluid then the cylinders in back, the valve feeds fluid to the rear at a slower rate then the fronts. It "proportions" the rear brakes, trying to also provide a 60/40 brake balance rate (or whatever it is). The stock valve isn't always successful at this, and/or, some folks have a custom setups, which is why adjustable valves are available [Note: This has been a somewhat simplified explaination].
Your problem sounds more like a bad master cylinder, and possibly gummy/dirty fluid! You may also have water in the fluid (brake fluid absorbes water). Particularly since you have some play before the brakes apply. Probably worn rubber. Rebuild or replace it before it quits altogether.
Your problem sounds more like a bad master cylinder, and possibly gummy/dirty fluid! You may also have water in the fluid (brake fluid absorbes water). Particularly since you have some play before the brakes apply. Probably worn rubber. Rebuild or replace it before it quits altogether.
Last edited by Polkat; Oct 20, 2005 at 08:23 PM.
Senior User
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I just replaced it and the front brakes have had all the fluid flushed. The rear hasn't (yet - I'm putting a new axle in soon.. new brakes too). It's not that the pedal has a lot of play in it.. it's just hard to get it to go down to where it should go fast (like in an emergency).
Maybe the front calipers are sticky or something? Brakes seem to work fine though, and I know the front releases well. It rolls very nicely.
Maybe the front calipers are sticky or something? Brakes seem to work fine though, and I know the front releases well. It rolls very nicely.