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Old 12th October 2011, 14:02   #1
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DIY Gravity Brake Bleeding

Tried searching for this DIY on the TBHP forum, but unable to find anything.

I have been searching about brake bleeding and brake fluid replenishment on the net and came across this simple DIY method of flushing the old fluid and replenishing it with new.

The procedure involves:

1. Opening the lid to the master cylinder
2. Siphon off the excess fluid directly from the cylinder, leaving just a little towards the bottom (optional, but if done, will allow new fluid to enter the system faster)
3. Top up with new brake fluid (don't mix DOT3/4)
4. Leave the master cylinder lid open (atmospheric pressure?)
5. Reach for the wheel farthest from the master cylinder (typically one of the rear wheels)
6. Open the bleeder valve a little so the brake fluid starts dripping out (alternatively you could attach a plastic pipe to the valve and collect the old fluid in a container)
7. Continue this till the new liquid starts coming out of the valve (during this dripping process, keep watching the master cylinder. If the fluid level seems to be going down, top up with the new fluid. Never run the master cylinder dry or you will have to repeat the whole process)
8. Once the valve starts dripping the new liquid, close the valve.
9. Repeat the procedure #6 onwards onto the other wheels (any specific sequence to be followed, for e.g. if I start with the rear RH wheel, should I then take the front LH wheel? Or do I go for both rear wheels first, before moving onto the front wheels?)

This method does not involve any specialized tools (other than probably a plastic pipe and a container to gather the drained fluid) and does not involve pumping of the brakes. So it's quite simple, actually.

Has anyone tried this DIY and with what results?

I am thinking of trying it on my Ikon, as the brake fluid may already warrant a replacement.
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Old 12th October 2011, 14:11   #2
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Re: DIY Gravity Brake Bleeding

The fluid wont drip out just by opening the bleeder nipple as the viscosity and density of fluid is such that atmospheric pressure is insufficient to pressurize it and throw it out of bleeder nipple.

Pumping of brakes will be required.
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Old 12th October 2011, 14:22   #3
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Re: DIY Gravity Brake Bleeding

Some observations :

- How will you know if the new fluid had started bleeding from the rear wheel, if the colour of the fluid is same.
- Oil bleeding by Gravity will take hours
- The bleeder valves are sometimes hard to open/ reach and at the inside of the wheel, if you break something you will end up paying more than you thought you would spend.

You dont have to do this frequently so get it done during your service.
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Old 12th October 2011, 14:26   #4
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Re: DIY Gravity Brake Bleeding

Good thread.
One question - on many vehicles, brake fluid and clutch fluid are the same. In this case, if I want to bleed both, will it have to be done separately for the clutch master cylinder and brake master cylinder?

Thanks.
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Old 12th October 2011, 14:27   #5
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Re: DIY Gravity Brake Bleeding

The car would be jacked up at the wheel, and the tyre would be removed. This can provide easier access to the bleeder valve (though I must confess this will also take more time).

Won't the colour have changed over the years? If not, this problem will persist in any type of bleeding, won't it?

I have also read that gravitational bleeding won't work if the master cylinder is positioned level with the wheel cylinders/calipers, which is not the case here. Fine, you may not see a running drip immediately, but will it just be impossible without depressing the brake pedal?

Please note: These are simply questions coming to my mind, as I am no expert in these matters.

@ anandpadhye, thanks for mentioning the clutch. The Ikon has the same setup: Brake fluid and clutch fluid is shared. So I too have the same question: Will replacing the brake fluid also replace the clutch fluid, or will the clutch need to be bled and replenished separately?

Last edited by honeybee : 12th October 2011 at 14:30. Reason: Added query on clutch fluid replacement
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Old 12th October 2011, 15:50   #6
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Re: DIY Gravity Brake Bleeding

@ Honeybee
I just want to know if your intension is to flush the entire system and fill with new fluid. How many kilometers did you run with the existing fluid.
The bleed screw is always on the top most point of the wheel cylinder. So by opening it up and draining the fluid your are ignoring a part of the brake fluid inside the wheel cylinder and at a level below the brake line attachment. And most of the dirt will stay stagnant at the bottom of the cylinder. I have tried it on my 118NE. The results wont be anything worth appreciating if the brake system is drained and filled by gravity. As well if the car has done 70 - 80K on the odo, I think it you would experience better results with replacing the wheel cylinder kits. I can help on this if you want a DIY.

In your procedure for gravity bleeding, this is a small suggestion I would like to add on point no 6. Always better to attach a small pipe to the bleed screw and collect the drained oil and dispose it off in a safe manner than letting it down on the soil.
Regards,
Ilango
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Old 12th October 2011, 16:47   #7
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Re: DIY Gravity Brake Bleeding

Gravity bleeding works, but very slowly, and the chances of inducing air are higher than pressure or vacuum bleeding. If there is no second person to help, and one has lots of time, it can be an appropriate way to get fresh fluid in the system without too much hassle.
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Old 12th October 2011, 17:09   #8
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Re: DIY Gravity Brake Bleeding

Yep requires pumping the brakes as well.

And yes things could get messed up and I would get this done at the authorized center not a DIY for me. - but then maybe 10-15 years before who knows - but somehow not for me now.

Thanks still you got the steps in correctly except for the pumping bit.
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Old 12th October 2011, 17:53   #9
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Re: DIY Gravity Brake Bleeding

ilangpop, for the Ikon I don't know when the brake fluid was last changed. The car has already completed ten years before I acquired it and the brakes are sure hard to pump and a bit slow in biting. During the suspension work the mechanic did say the brake pads looked alright, but again if they have been on the car for ten years, they might just be replaced. So I might replace the brake pads, liners and the fluid all in one go.

Cylinders may not need a replacement unless they are leaking, so your question on the old oil in the cylinders might be a worry. I have also read that tapping the cylinders gently while gravity-bleeding them helps.

Why discuss this approach? Because this is the simplest approach a single person can take to change the brake fluid. Any more and it might be better to pay the mechanic to get it done.

I am not looking at a DIY for a cylinder change, but if you can post a DIY tutorial, I shall go through it and see if I could give it a shot. I have gone through SirAlec's tutorial on the front brake pad change, and it sure is interesting to know how the work is performed. So whether I do it or not, I would request you to please share the DIY.
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Old 12th October 2011, 22:28   #10
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Re: DIY Gravity Brake Bleeding

DIY tools can be made by using pearlpet jars. very easy to make but little time consuming. i have bought all the stuff beginning of the year but didn't start due to other work that were more important. Will definitely do this in future when i have little bit more time.

now to the topic.
this is not the effective way to do it. As it is painfully slow, the brake fluid will flow even if there is air in the system.

Quote:
Siphon off the excess fluid directly from the cylinder, leaving just a little towards the bottom
This is how air goes inside the system. people driving without checking the correct level.

Last edited by SirAlec : 12th October 2011 at 22:29.
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Old 12th October 2011, 22:42   #11
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Re: DIY Gravity Brake Bleeding

I have a ten year old ikon as well. 1.6 2000. I have noticed that the brake fluid is a pale green instead of the usual crimson. On research I found that it should be pale yellow / colourless. I have dealt with brake fluid before but this is about the first time I have seen pale green.

My guesses are that it is contaminated or ford has some special fluid. Can anyone confirm if pale green is the right colour? much appreciated
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Old 13th October 2011, 12:23   #12
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Re: DIY Gravity Brake Bleeding

Quote:
Originally Posted by SirAlec View Post
This is how air goes inside the system. people driving without checking the correct level.
How about making a pinhole into the protective cover on the brake fluid container (new one) and turning it upside down into the master cylinder, so that it starts a drip of the fresh fluid into the master cylinder, while you open each bleeder valve and bleed the old fluid out?

If this can remove 99% of the air, though slowly, I think it would still be worth while to try it.
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Old 13th October 2011, 15:00   #13
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Re: DIY Gravity Brake Bleeding

I have tried this in my car and faced 2 problems:
1. it is s--l--o--w
2. air did seep in; despite ensuring that the brake master cylinder always had fluid upto the halfway mark. So ultimately had to bleed the brakes by pumping.
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