Brake Fluid change

[hypervish]

Hey everyone, hope everyone is doing well and happy holidays!

I want to change out my brake fluid sometime next week after my road trip. I don't want to damage the master cylinder as I've heard that's easy to do when bleeding brakes.

Here is the procedure I plan on using, please let me know if it's safe for the master cylinder.

1. Open brake fluid cap.
2. Pump brakes.
3. Open bleeder valve.
4. Close valve.
5. Pump brakes again.
6. Open bleeder valve.
7. Close valve.
8. And, continue that till the fluid is clean and I've done all 4 calipers.
9. Finally, close the brake fluid cap. ( I will monitor brake fluid and add as needed throughout the whole procedure)

 

[Cardenio327]

Your plan sounds good to me.

I'm probably going to get jumped for saying it, but if you damage the master cylinder by pumping it to the floor when bleeding you need a new master cylinder anyway. Worrying about debris or residue applies to fossilized collector cars that aren't daily drivers. If it were mine, and a daily driver, I wouldn't worry one bit about it. Besides, if you keep it bled out every 2 or 3 years there won't be enough residue in there to cause a problem.

 

[RiceCake]

Only issue is it can be a serious pain to do it that way without someone to hold the brake pedal down when you crack the bleeder open. Some cars you barely get a trickle of fluid without someone holding real pressure on it.

But yes that should work, just don't let the reservoir get too low like you said and you should be okay.

 

[hypervish]

Originally Posted By: Cardenio327
Your plan sounds good to me.

I'm probably going to get jumped for saying it, but if you damage the master cylinder by pumping it to the floor when bleeding you need a new master cylinder anyway. Worrying about debris or residue applies to fossilized collector cars that aren't daily drivers. If it were mine, and a daily driver, I wouldn't worry one bit about it. Besides, if you keep it bled out every 2 or 3 years there won't be enough residue in there to cause a problem.


That's the thing, *puts flame suit on* I haven't bled the system in at least 7 years.

Would it be safe if when I pumped the brakes I didn't take them all the way to the floor, just half-way?

 

[hypervish]

Originally Posted By: RiceCake
Only issue is it can be a serious pain to do it that way without someone to hold the brake pedal down when you crack the bleeder open. Some cars you barely get a trickle of fluid without someone holding real pressure on it.

But yes that should work, just don't let the reservoir get too low like you said and you should be okay.


I'll keep that in mind. I will have a second person handy, if need be.

 

[yonyon]

If you're going to have a second person handy, you might as well just put them in the car to save time.

I once had that not work out for me as my handyperson kept pressing the wrong pedal.

 

[JamesBond]

If you are by yourself you can just gravity bleed the brakes. Open cap, wrench on bleeder, hose on bleeder in a question mark shape "?" with open end in a bottle or jar, then open the bleeder. It's a slow process but it requires little supervision, you could run out and check on it during the commercials. The higher the master cyl. is in relation to your bleeder valves, the better this works. Your suv should work fine.

 

[Donald]

Originally Posted By: hypervish
Originally Posted By: RiceCake
Only issue is it can be a serious pain to do it that way without someone to hold the brake pedal down when you crack the bleeder open. Some cars you barely get a trickle of fluid without someone holding real pressure on it.

But yes that should work, just don't let the reservoir get too low like you said and you should be okay.


I'll keep that in mind. I will have a second person handy, if need be.
A second person can also pass the beer.

 

[tig1]

Every engine oil change I turkey baster my master cyl and PS pump.

 

[heyu]

I always had good luck just changing out the fluid in just the master cylinder alone ,all the fluid in the lines does purge back and forth back to the cylinder so draining the master cylinder and refilling 3 - 4 times is usually all clean after that AND as mentioned above,,a turkey baster works great

 

[hypervish]

Thanks for the advice guys! I appreciate it.

 

[mechtech2]

Suck out the old fluid first, and put in fresh.
THEN start your bleed.
In this case, there should be absolutely no need to pump them up.
Slowly press the pedal, open the bleeder , then shut the bleeder before you hit bottom.

For one man a vacuum bleed is fantastic.
Good luck with a two man bleed.You have to be in EXACT synch. And people lie.

 

[RiceCake]

Originally Posted By: heyu
I always had good luck just changing out the fluid in just the master cylinder alone ,all the fluid in the lines does purge back and forth back to the cylinder so draining the master cylinder and refilling 3 - 4 times is usually all clean after that AND as mentioned above,,a turkey baster works great


Not really. Your brake lines are very long, narrow, and have no cyclical flow. Changing the brake fluid in the master cylinder regularly does cause a tiny bit of fluid to cycle into the top of the lines, but even in a million stops I doubt it will never cycle more then %5 new fluid to even the halfway mark down the lines.

 

[Jim Allen]

Originally Posted By: mechtech2
Suck out the old fluid first, and put in fresh.
THEN start your bleed.
In this case, there should be absolutely no need to pump them up.
Slowly press the pedal, open the bleeder , then shut the bleeder before you hit bottom.

For one man a vacuum bleed is fantastic.
Good luck with a two man bleed.You have to be in EXACT synch. And people lie.


^This is the way.

If you release the brake pedal with the bleeder open, you will suck air back into the system.

I recently changed the brake fluid in our Honda Accord. I have an stick I wedge between the steering wheel and the brake pedal when it's on the floor. Go back, close the bleeder, repeat. Use a clear plastic hose from the bleeder to a catch can

I have often gravity bled vehicles; i.e. you suck out the reservoir, fill it with fresh, then open the bleeder farthest from the m/c (clear hose attached to bleeder). In many systems, gravity will allow the fluid to slowly dribble into you catch can and you can observe the color of the fluid. When it comes out clean, you can close the bleeder and move on to the next bleeder. Obviously, you keep the reservoir full. No air enters the system. It may take a while but you can do other service things at the time. I just did this with my old Ford F250. Tried it with the Honda Accord but it didn't work well.. I presume it was the ABS plumbing, so I used the method above.

 

[Bgallagher]

Pretty standard my friend. You got it!

Remember to start at the farthest caliper from the master and work your way up. usually when I am doing this I would adjust my rear brakes (if drums) and clean the brakes. Might as well when you are in there

 

[mechtech2]

I am quite familiar with starting at the farthest wheel when bleeding. Everyone has heard this.
The more I think about it, the less I am convinced that this is necessary at all. In a closed hydraulic system, a good bleed ends up the same.

BTW, with ABS systems, do your homework first on your specific car! Many require specific bleed techniques.

 

[Jim Allen]

Originally Posted By: mechtech2
I am quite familiar with starting at the farthest wheel when bleeding. Everyone has heard this.
The more I think about it, the less I am convinced that this is necessary at all. In a closed hydraulic system, a good bleed ends up the same.

BTW, with ABS systems, do your homework first on your specific car! Many require specific bleed techniques.


Good point. I remember some being quite bizarre.

 

[charbaby]

I like the hand held vacuum pump(~$35).

I don't like the 2 person bleed as the MC piston can often score it's own cylinder wall or it's seal(if pushed too far) and can lose pressure from there on causing the replacement of the MC. This happens to alot of people.

Some MC pistons won't extent that far but, IDK which ones will and which ones won't. You'll never know until it happens!

Remove the brake fluid as-much-as possibe from the MC and pour in fresh fluid.

Using the vacuum pump, bleed each brake one at a time in the proper order by the MFG, pumping up the vacuum to the proper Hg & cracking open the bleeder and doing this several times for each brake until you're satisfied, keeping the MC resivior full until you're complete.

 

[Vikas]

Quote:
I don't like the 2 person bleed as the MC piston can often score it's own cylinder wall or it's seal(if pushed too far) and can lose pressure from there on causing the replacement of the MC. This happens to alot of people.


Suppose there is a ridge formed in the master cylinder.

My question:- What if I had to emergency brake somebody and stood on the pedal? Is my pedal going to give in during that braking?

Wouldn't it be better to find and fix the ridge before that happens?

What are the holes in my logic?

 

[charbaby]

Originally Posted By: Vikas
Quote:
I don't like the 2 person bleed as the MC piston can often score it's own cylinder wall or it's seal(if pushed too far) and can lose pressure from there on causing the replacement of the MC. This happens to alot of people.


Suppose there is a ridge formed in the master cylinder.

My question:- What if I had to emergency brake somebody and stood on the pedal? Is my pedal going to give in during that braking?

Wouldn't it be better to find and fix the ridge before that happens?

What are the holes in my logic?


Well, IDK the answer to any of your questions but, I have stood on my brake pedal in an emergency/panic situation and, the brake pedal didn't go to the floor. As long as the braking system(master cylinder/power booster) is in good condition, the pedal should hold pressure in situations like that.

The only time I have ever had the brake pedal go all the way to the floor is when I did a 2 man bleed or when the MC was in need of replacement.

But, I can't really say what would happen in all situations...Hope for the best, I guess!