Brake Fluid Flush Technique

[artbuc]

Years ago on another forum, a person I respected greatly for his auto repair knowledge said he always cracked the bleeder and compressed caliper piston as the first step in replacing brake fluid. He said it was good to expel old fluid in the caliper to make sure it was completely flushed. His theory was that if you just open the bleeder you do not get pure plug flow and some old fluid will not get flushed as it sits stagnant in the caliper. This made sense to me and I adopted that practice. It means a lot of extra work so I couple brake fluid flushes with tire rotation and/or routine caliper service. Anyhow, was just wondering what you all think about this. Is it worthwhile to compress clipper pistons to expel old fluid? Thanks.

 

[CharBaby]

Well, it is just another method of achieving the same end result. But, maybe there is some validity to this and I do understand his/your reasoning! This seems like a good PM during a tire rotation...just remove the old fluid from the caliper(between complete flushes) where the most heat builds up!

I have talked to guys who, like to bleed/flush between brake jobs. And I have talked to others who, like to bleed/flush during tire rotations. And several who, like to bleed/flush about every 2 years whether they're installing new brakes or not. And I have talked to many who, don't ever bleed/flush, not even when doing a brake job. That last one is just messed up!

When I bleed brakes, I alway remove as much brake fluid from the reservoir and add new fluid as my first step. Then I bleed/flush starting with the furthest caliper away from the M/C.

Should I ONLY be installing new brake pads, I always open the bleeder valve when pressing in the caliper piston, as not to push back old fluid into the system. Lots of people do this!

 

[demarpaint]

I siphon some fluid from the reservoir replace it with clean fluid. Then I crack the bleeder and have someone step on the brake. When the pedal is bottomed I close the bleeder and they release the pedal. Then I crack the bleeder and let gravity do its thing. I repeat the process for each bleeder. I do this every three years, usually with a tire rotation. I start with the right rear caliper.

 

[CharBaby]

Originally Posted By: demarpaint
I siphon some fluid from the reservoir replace it with clean fluid. Then I crack the bleeder and have someone step on the brake. When the pedal is bottomed I close the bleeder and they release the pedal. Then I crack the bleeder and let gravity do its thing. I repeat the process for each bleeder. I do this every three years, usually with a tire rotation. I start with the right rear caliper.


Indeed! Although, I have stopped using the 2 person method as, I can't often find the 2nd person to HELP! Plus, using 2 people with one pressing on the brake pedal(on certain vehicles) this method has often destroyed the brake master cylinder(M/C) by, scoring the cylinder wall from pressing the pedal tooooo far/fast! Usually on cars such as Pontiac Grand Am's and similar older GM's. And it can happen to other vehicles!

I like using a Mityvac or gravity bleeding as I am just more comfortable doing so! But, I know tons of people still using the 2 person method without issues!

 

[SteveSRT8]

It is always worthwhile to open the bleeder when compressing pistons back into the caliper. Mostly to protect the MC, but fluid replacement is a great idea.

On track days one of my many preps was to gravity bleed the entire system until clean fluid is seen at each wheel...

 

[demarpaint]

Originally Posted By: Char Baby
Originally Posted By: demarpaint
I siphon some fluid from the reservoir replace it with clean fluid. Then I crack the bleeder and have someone step on the brake. When the pedal is bottomed I close the bleeder and they release the pedal. Then I crack the bleeder and let gravity do its thing. I repeat the process for each bleeder. I do this every three years, usually with a tire rotation. I start with the right rear caliper.


Indeed! Although, I have stopped using the 2 person method as, I can't often find the 2nd person to HELP! Plus, using 2 people with one pressing on the brake pedal(on certain vehicles) this method has often destroyed the brake master cylinder(M/C) by, scoring the cylinder wall from pressing the pedal tooooo far/fast! Usually on cars such as Pontiac Grand Am's and similar older GM's. And it can happen to other vehicles!

I like using a Mityvac or gravity bleeding as I am just more comfortable doing so! But, I know tons of people still using the 2 person method without issues!

Good point about the two person method. One thing worth mentioning is the assistant slowly and steadily pushes the pedal to the floor, they are told not stop it through the firewall. When they feel it kiss the floor they hold it there and I tighten the bleeder. I do this once, then let gravity take over. I've been doing this for many years with no issue, but your point is well taken.

I like the Miti Vac idea and might invest in one. This way I don't have listen to my wife complain when I tell her I need her to help. LOL

 

[Falken]

Here is another really good tip:

If your piston is extended all the way out, before pushing it back in clean it with a bit of canned or compressed air to remove dirt and brake dust.

Then take a pea sized glob of high quality Wurth silicone lube and wipe it on the piston BOOT.

This is done to prevent it from tearing when you compress it back into the caliper.

If the boot binds when it is dirty and dry, it will tear. Cleaning it and using silicone grease eases it back into the caliper tear-free.

Always do this, a torn piston boot is a bummer.

 

[CharBaby]

Oh yeah indeed! I have used the 2 person method for many years in the past. I don't do it today mostly(MOSTLY) due to not having a helper!

But, I caution others when doing a 2 person method, as this cylinder scoring is always a possibility(not a given)! Just Cautious is all!

Good thread for sure!

CB

 

[barkingspider]

I rotate my tires once a year (5000-7500 miles), I use the 2 person method and I flush the rears brakes one year, then I do the fronts the next year. Never had problems using regular dot3 in my vehicles. I will try the gravity method next. I think my wife will appreciate it.

 

[Astro14]

I have a Motive Power Bleeder. I flush the fluid annually on the Euro cars.

Siphon out old fluid in the Master cylinder, refill with fresh, hook up the motive and pressurize it, start with the farthest caliper, let the fluid run until the color changes (fresh fluid, used to use ATE Super Blue, alternating with regular DOT-4, then it was easy to see, but you can still see the old/new difference)...then let it run a bit more, close the bleeder and move on to the next caliper.

I'm certain that I got all the old fluid out, you can see the color start to change pretty quickly (new fluid mixing with old) but once the color change stops, there is no more old fluid being mixed...it's all new fluid in that caliper.

By the way, in the 8 years that I've had this thing, and the cars on which I use it, I've not replaced a single caliper, master, or hydraulic component. I've done rubber hoses for age/cracking but the hydraulic components last a long, long time when the fluid is kept fresh.

 

[SteveSRT8]

Originally Posted By: Astro14

By the way, in the 8 years that I've had this thing, and the cars on which I use it, I've not replaced a single caliper, master, or hydraulic component. I've done rubber hoses for age/cracking but the hydraulic components last a long, long time when the fluid is kept fresh.


Here we have not replaced a caliper in ages. Admittedly our weather is part of it, but in my sig car purchased August 05 the calipers are 4 piston fixed Brembos and they are OEM...

 

[HTSS_TR]

Originally Posted By: artbuc
Years ago on another forum, a person I respected greatly for his auto repair knowledge said he always cracked the bleeder and compressed caliper piston as the first step in replacing brake fluid. He said it was good to expel old fluid in the caliper to make sure it was completely flushed. His theory was that if you just open the bleeder you do not get pure plug flow and some old fluid will not get flushed as it sits stagnant in the caliper. This made sense to me and I adopted that practice. It means a lot of extra work so I couple brake fluid flushes with tire rotation and/or routine caliper service. Anyhow, was just wondering what you all think about this. Is it worthwhile to compress clipper pistons to expel old fluid? Thanks.

I think this method of compressing the caliper is better, but it requires a lot more work.

Originally Posted By: demarpaint
I siphon some fluid from the reservoir replace it with clean fluid. Then I crack the bleeder and have someone step on the brake. When the pedal is bottomed I close the bleeder and they release the pedal. Then I crack the bleeder and let gravity do its thing. I repeat the process for each bleeder. I do this every three years, usually with a tire rotation. I start with the right rear caliper.

You have Mityvac 7201, you can use it to bleed the brake, it's very easy, fast and no chance for air to get into brake system. I used Mityvac 7201 to bleed my car brakes many times without any problem.

I had Motive power bleeder with several adapters, it didn't work well for the rear brakes of both LS400 and E430, I sold it on eBay and Craigslist. I had been using Mityvac 7201 for more than 7-8 years now.

 

[demarpaint]

Originally Posted By: HTSS_TR


Originally Posted By: demarpaint
I siphon some fluid from the reservoir replace it with clean fluid. Then I crack the bleeder and have someone step on the brake. When the pedal is bottomed I close the bleeder and they release the pedal. Then I crack the bleeder and let gravity do its thing. I repeat the process for each bleeder. I do this every three years, usually with a tire rotation. I start with the right rear caliper.

You have Mityvac 7201, you can use it to bleed the brake, it's very easy, fast and no chance for air to get into brake system. I used Mityvac 7201 to bleed my car brakes many times without any problem.

I had Motive power bleeder with several adapters, it didn't work well for the rear brakes of both LS400 and E430, I sold it on eBay and Craigslist. I had been using Mityvac 7201 for more than 7-8 years now.


I'm impressed that you remembered!

Thanks for reminding me, I have not tried it yet with the Miti-Vac and really should. I use it for extracting ATF which has been great. Next time I will try it for brake fluid flushes. Thanks again!!!!!

 

[HTSS_TR]

I don't remember which member has what tool, you are one of a few I remember. Probably because you're special and probably because your son is serving our country in uniform, and it is a very special to me, that is why I remember what you bought.

What you need to do brake bleeding with Mityvac 7201 is a thick but flexible hose that fits the bleed screw snugly. Connect this 8-12" hose(you can but it at any hardware store) to the black adapter then to the main hose then to reservoir. After all connections are done pump the Mityvac 2-3 times before loosen bleed screw, this will not let any corrosive brake fluid on any car part.

 

[demarpaint]

Originally Posted By: HTSS_TR
I don't remember which member has what tool, you are one of a few I remember. Probably because you're special and probably because your son is serving our country in uniform, and it is a very special to me, that is why I remember what you bought.

What you need to do brake bleeding with Mityvac 7201 is a thick but flexible hose that fits the bleed screw snugly. Connect this 8-12" hose(you can but it at any hardware store) to the black adapter then to the main hose then to reservoir. After all connections are done pump the Mityvac 2-3 times before loosen bleed screw, this will not let any corrosive brake fluid on any car part.


Thanks! And thanks for the tips on how to use it. At some point this summer my Jeep is due for a brake fluid flush, I will check it out! It sounds like a clean and easy way to use the tool.

 

[cjcride]

Originally Posted By: demarpaint
Originally Posted By: HTSS_TR
I don't remember which member has what tool, you are one of a few I remember. Probably because you're special and probably because your son is serving our country in uniform, and it is a very special to me, that is why I remember what you bought.

What you need to do brake bleeding with Mityvac 7201 is a thick but flexible hose that fits the bleed screw snugly. Connect this 8-12" hose(you can but it at any hardware store) to the black adapter then to the main hose then to reservoir. After all connections are done pump the Mityvac 2-3 times before loosen bleed screw, this will not let any corrosive brake fluid on any car part.


Thanks! And thanks for the tips on how to use it. At some point this summer my Jeep is due for a brake fluid flush, I will check it out! It sounds like a clean and easy way to use the tool.
Clear hose is best.

 

[cronk]

I always crack the bleeder open before compressing a caliper piston while doing a brake job. It's amazing the dark nasty fluid that comes out, certainly don't want to push that junk back up the lines. When it's all back together, I siphon all the old fluid from the master cylinder, replace with fresh fluid, and crack the bleeders and let them gravity bleed till clear fluid comes out.

 

[jk_636]

Easiest method to flush the brake system? Thats an easy one.

Step 1. Drive to an authorized BG service center.

Step 2. Pay money for brake flush and service.

Step 3. Drive home.

It is as easy as 1,2,3!

 

[GenesisGuy70]

Originally Posted By: jk_636
Easiest method to flush the brake system? Thats an easy one.

Step 1. Drive to an authorized BG service center.

Step 2. Pay money for brake flush and service.

Step 3. Drive home.

It is as easy as 1,2,3!

+1. I hate bleeding brakes.

 

[HTSS_TR]

Originally Posted By: Throt
Originally Posted By: jk_636
Easiest method to flush the brake system? Thats an easy one.
Step 1. Drive to an authorized BG service center.
Step 2. Pay money for brake flush and service.
Step 3. Drive home.
It is as easy as 1,2,3!

+1. I hate bleeding brakes.

What I hate doing brake bleeding are: raise the car, put jack stands under the car, remove the wheels, reinstall the wheels, remove jack stands, lower the car. These are the kind of work I hate the most, brake bleeding with right tool is as easy as a walk in a park.