Gravity brake fluid flush

[barryh]

If you have the time, what I like about gravity bleeding is that provided you keep the reservoir topped up there is zero chance of introducing air. In my experience it's vacuum bleeding that pulls air in around the bleed nipple threads. I've never had that problem with gravity.

Gravity bleeding has got a touch quicker since the advent of low viscosity fluids and I would always do it in warm weather too.

I admit I would use pressure bleeding if I had the kit but gravity bleeding is the same in principle just at a lower pressure that the head of fluid provides. I've found it works nicely on motorcycles which have much shorter brake lines and greater head height of fluid so the fluid flows faster.

 

[DCDG]

I admit I would use pressure bleeding if I had the kit but gravity bleeding is the same in principle just at a lower pressure that the head of fluid provides. I've found it works nicely on motorcycles which have much shorter brake lines and greater head height of fluid so the fluid flows faster.

I pressure bled in the past it worked out fine but still didn’t have the pedal feel I was looking for. One man bleeding with a final gravity bleed cured the famously soft rogue pedal feel wasn’t perfect but livable.

 

[Capt W]

The one-person methods are cool indeed, but my wife would feel neglected if she wasn't in the driver's seat hearing me yell "DOWN and "UP" for 15-20 minutes.

 

[DCDG]

The one-person methods are cool indeed, but my wife would feel neglected if she wasn't in the driver's seat hearing me yell "DOWN and "UP" for 15-20 minutes.

It’s a one person bleed I don’t rely on a pumper. I do it myself now, last pumper I had made my brake pedal and master develop a creaking groan by over pumping the pedal.

 

[oilboy123]

Yes I pull old fluid out of the reservour. Refill, then get a hose with a bottle on all 4 wheels. I crack the bleeders, and will push on the pedal a few times. But not too far on the pedal.
I will have to see if my newer scan tool can activate my ABS. But I would need to maybe just do one wheel at a time. With the hose securely to the bleed screw.

 

[Capt W]

last pumper I had made my brake pedal and master develop a creaking groan by over pumping the pedal

Careful now...this is a family-friendly forum

 

[JeffKeryk]

Worst cars to bleed properly are the C3 Corvette disc brakes. You have to pressure bleed them, on low pressure.

 

[HowAboutThis]

Hi,
Planning to change my brake fluid on my 2016 Mazda 3 (~80K miles). I might just do gravity as it is much simpler.

Is there any benefit between the gravity method and 2 person or just time savings?

The process seems to be opening the bleeder screws and keeping the reservoir topped up?

On a 99 and 02 I used gravity and a MityVac years ago. Now, for $100, I let the dealer do it because they also cycle the ABS for a full exchange.

Gravity on the old Hondas was fine. I just stuck buckets under each with a piece of hose connected and loosened all the bleeder screws. Then I'd do something else in the garage but frequently check the reservoir. It'd start running clean after about 15-20 minutes. The MityVac was faster as it would suck the fluid through quickly.

Aside from not activating the ABS, don't know if Mazdas like one method versus another.

 

[wtd]

I've rarely done the gravity bleed method and in a couple of instances where I had to replace some brake lines, gravity bleed did not work at all. In those instances, the vacuum bleed method also did not work, and I had to have a partner pump the brake pedal to get it to bleed.

I've have mostly used a vacuum bleeder both with a manual pump and with one that hooked to an air compressor and they both did decent jobs other than I did have to put grease around the bleeder valves because the process would draw air from around the threads and you would always get air bubbles in the fluid unless you added the grease.

A few years ago, I bought a pressure bleeder, and it is now my preferred method of bleeding. It's a lot faster and does a great job.