Bleeding Brakes - Gravity Bleeding

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I just wanted to report in that gravity bleeding seems to work well enough.

I have a Ford F150 that I routinely do maintenance on by myself, so letting each caliper drip seemed to do the trick.

I'm going to guess it is easier on a truck since the height difference between the master cylinder reservoir and the calipers is greater than on a car. (I managed to gain some more height by jacking up the driver front corner)

The rear brakes had a fast drip while the fronts had a steady flow. The entire process took about 1.5 hours from beginning to cleanup, so you can work on other projects while each caliper bleeds out.

I have a Motive Power Bleeder on order because I haven't changed my fluid in a while. I'll need to do a few bleeding sessions to return the fluid color to the normal clear yellow it should be.

I guess the best part is that you really have no way of introducing air into the system since it goes so slow.
 
Originally Posted By: Audi Junkie
I bleed it dry and then refill. Works perfectly.


Is that safe to do? That seems to be the most efficient way to get new fluid into the system, but I imagine with all the plumbing that there are pockets of air that would cause problems later on.
 
Originally Posted By: Audi Junkie
I bleed it dry and then refill. Works perfectly.


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i would say letting everything go dry would be a bad thing on a car with ABS, unless you have a ABS capable scan tool.

when i turned wrenches, i would use a vacula, and if the pedal didnt get the way i liked it, i would follow up with a manual bleed with another tech. when i used the vacula, i had an autofiller on the master, basically a drip bottle.
 
I let them bleed almost dry and fill. Keep a light behind so you can monitor the exact level. Letting air in may make gravity bleeding ineffective.
 
I like to use ATE brake fluid that comes in blue and "gold" color. You alternate between the two and the color change tells you when the fresh fluid has come through.

I would never bleed a system dry unless I had to. Might work okay on some cars, but on others it can be a nightmare to get all the air out. Stubborn air bubbles can cling to crevices and corners all through the system.
 
Some thoughts on bleeding brakes:

No need to bleed the system dry. If you let some ABS valve blocks leak down, you may need specialized tools to refill and correctly re-bleed them. It's ok to leave the fluid stuck in the ABS block. That fluid leads a relatively cloistered life and is usually in good shape. But if you need to, you can run a couple "panic" stops post-flush to engage the system and mix in fresh fluid. Best to do this in winter on a snow covered parking lot. If you are changing fluid composition, then you have to bleed the ABS block.

I much prefer pressure bleeding to gravity bleeding. I don't have hours to fuss with fluid changes. If you repeatedly top off the master cylinder reservoir with fresh fluid, you can use the motive pressure bleeder effectively with just air pressure. It's much easier to clean up the motive tank later (there's no mess).

On older vehicles, you don't want to pump the master cylinder for bleed pressure, as this takes the seals outside of their wear patterns and often results in a master cylinder failure shortly thereafter.

The Typ200/Super Blue fluid swap is a popular technique on track vehicles. But believe it or not, ATE Super Blue, even though it is the exact same fluid as Typ200, is NOT DOT compliant for street use, due to the blue dye. Crazy DOT rules.
 
Just to add in since I hope this thread can be useful later on:

Up until the gravity bleed I mentioned in the first post, I had NEVER bled the brakes for 65k miles. Fortunately, I only lost a small amount of pedal firmness.

When I was draining the fluid out, it was BLACK and GREEN. Now that I have some fresh fluid in the system, it is less black and more green/light green. The pedal is noticeably firmer now, as well.

I'll be using the Motive bleeder to effectively bleed out the system a little at a time. At this point, it is difficult to tell apart the new fluid from the old. I imagine 3-4 sessions with the motive should result in crystal clear yellow brake fluid and a very firm brake pedal.
 
I would never bleed a modern (ABS) system dry. While many get by doing it I feel it is asking for trouble. My first choice is a professional pressure bleeding system. At Home I prefer to do a pressure bleed using a check valve on the caliper (speed bleeders) or a second person. I also notice that different vehicles have different sequences (RF, LR etc) to minimize contamination.
 
I had to replace the rear brake lines in my 528e. As said, it is a bad thing to let the ABS run out of fluid. I kept topping off the reservoir to prevent this. The whole process consumed about a qt of fluid. It was a combined flush and gravity bleed. I followed up ith a classic 2 man bleed and the brake pedal never felt so good.
 
Originally Posted By: andyd
, it is a bad thing to let the ABS run out of fluid.


That's why using a pressure bleeder is so convenient. The pressure bleeder keeps topping off the reservoir with fresh fluid. The pressure bleeder can also be assisted by pumping the pedal gently. Very easily done by one person.
 
Originally Posted By: Audi Junkie
I said my part and never had a problem draining the systems fully.


In case of your B5, how'd you get the fluid out of the ABS control unit without cycling it?
 
Originally Posted By: Volvohead
Some thoughts on bleeding brakes:

No need to bleed the system dry. If you let some ABS valve blocks leak down, you may need specialized tools to refill and correctly re-bleed them. It's ok to leave the fluid stuck in the ABS block. That fluid leads a relatively cloistered life and is usually in good shape. But if you need to, you can run a couple "panic" stops post-flush to engage the system and mix in fresh fluid. Best to do this in winter on a snow covered parking lot. If you are changing fluid composition, then you have to bleed the ABS block.

I much prefer pressure bleeding to gravity bleeding. I don't have hours to fuss with fluid changes. If you repeatedly top off the master cylinder reservoir with fresh fluid, you can use the motive pressure bleeder effectively with just air pressure. It's much easier to clean up the motive tank later (there's no mess).

On older vehicles, you don't want to pump the master cylinder for bleed pressure, as this takes the seals outside of their wear patterns and often results in a master cylinder failure shortly thereafter.

The Typ200/Super Blue fluid swap is a popular technique on track vehicles. But believe it or not, ATE Super Blue, even though it is the exact same fluid as Typ200, is NOT DOT compliant for street use, due to the blue dye. Crazy DOT rules.



I just bought Valvoline heavy duty dot 3 for my camry down here and it's blue coloured... any problems with the dye? http://valvoline.com.au/files/productpdfs/61.pdf
 
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Originally Posted By: crinkles
I just bought Valvoline heavy duty dot 3 for my camry down here and it's blue coloured... any problems with the dye? http://valvoline.com.au/files/productpdfs/61.pdf


While I don't know if DOT 3 is okay for your Camry, the blue dye in itself is not an issue unless blue brake fluid is not street legal where you live. Alternating standard yellow with blue ATE brake fluid makes flushing brakes very convenient since you can tell when the old fluid has been replaced with the new one.
 
Originally Posted By: crinkles


I just bought Valvoline heavy duty dot 3 for my camry down here and it's blue coloured... any problems with the dye? http://valvoline.com.au/files/productpdfs/61.pdf


Don't know about down under, but here in the States, blue brake fluid is a "violation". I personally don't agree with it (Superblue is the EXACT same fluid as Typ200 except for the dye), but those are the regs.

Over on Swedespeed, one R owner had Volvo NA deny his brake failure warranty claim because he used Superblue and was not DOT compliant. R's come OEM with Typ200. Totally bogus claim denial, but that's how it can bite you.
 
Gravity bleeding works ok if all you're trying to do is get new fluid in. A bit time-consuming, but usually works well enough.

But if you're trying to get air OUT of a system... then gravity bleeding may or may not work. You'd be better off with a pressure bleeder, vacuum bleeder, or pumping the pedal with a helper.

Personally, I think it's a BAD idea to drain a brake system completely dry. You might get away with it... but there's no reason to do it that way, and it's just ASKING for trouble.
 
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