Brake fluid refresh?

Rat407

Rat407

Joined
Dec 13, 2002
Messages
2,640
Location
North Carolina
Poor mans brake fluid change. Been busy and with this heat here in NC I don't care to be outside much. I hate it when i have to change clothes several times a day because I soak them with sweat. Anyway, is it worth sucking out the brake fluid out of the reservoir and filling back up with fresh every few days to get some fresh fluid in the system until I can bleed each wheel properly? I usually do it when I replace my brake lining but at the rate I'm going that will be years from now since I don't put the miles on like I used to. I wish they wouldn't have banned ATE Super Blue brake fluid. It was nice seeing blue fluid come out an knowing for sure it was fresh at each wheel.
 
Not particularly, I don't know of any system which circulates the fluid so everything in the master cylinder typically stays in the master cylinder. Its the calipers which really matter and that fluid shouldn't make it's way there unless bleed.

That said the fluid does absorb moisture so it could in theory slightly lower the moisture content of the fluid overall but to what degree is a complete guess.
 
I've done that many times with great results. In fact, I do it every year. We don't have serious corrosion issues here in FL. But even so, my calipers do not rust from the inside. They generally corrode from the outside in. 15 years is about the limit.

I have never found internal corrosion or dirty fluid at the caliper.

When I change brake pads, I generally just squeeze the pistons in and suck the fluid out of the res.
 
I did the fluid change on my Suzuki last week. Yeah it was hot and I tested my personal cooling system to the max. Toughest part of the jay oh bee was lifting the wheels back into position. Torqued the lug nuts to about 90.

Great satisfaction. Like the Nike logo, 'just do it'.
 
I schedule PM work on my car (and house) in the Spring & Fall.
July & August are for doing quick, easy jobs (and relaxing).

Brake fluid gets 'flushed' every two years.
In between, I exchange the fluid in reservoir.

Everything is on a schedule, .... everything gets done.
 
3800Series said:
Not particularly, I don't know of any system which circulates the fluid so everything in the master cylinder typically stays in the master cylinder. Its the calipers which really matter and that fluid shouldn't make it's way there unless bleed.

That said the fluid does absorb moisture so it could in theory slightly lower the moisture content of the fluid overall but to what degree is a complete guess.
Click to expand...
Maybe if the car uses a brake-by-wire system with an accumulator or an older ATE/Bendix ABS system with an integral power booster - also with an accumulator. Toyota trucks that don’t use a vacuum booster use a similar brake actuator as a Prius or hybrid version of the Camry/Highlander/RAV4. There isn’t cycling of brake fluid in a loop but the actuator is repressurized.

My MO for brake fluid changes - every 30K or when pads get swapped out.
 
Personally, I've been doing the " Poor man's brake fluid change" for years with great results. Granted, it doesn't get the muck out of the calipers or wheel cylinders, ( if you have them), but, something is better than nothing. Once a year I'll do the poor man's way, then the 2nd year, if I have time, I'll bleed the entire system. I squeeze off the caliper lines, and push the muck out the bleeders. Try not to play around with the wheel cylinders too much. They have a tendency to leak if you push them back and forth . I slowly do those to get the junk out. Either way, it could be 2 years poor man, then complete bleed. Don't let it go any longer than that.
 
I have done fluid different ways, actually several thru the years. Not so much lately due to very limited miles per year + medical issues.

#1) Lowered and refilled master cylinder. Really the least effective method. (honest dealership techs will tell you) That is what they do when they "renew the brake fluid." :rolleyes: They really do not flush the entire system often at all these days. You must specifically request and then?

#2) Always used to bleed the lines to each wheel after doing brake relining jobs. Drained each into partially filled plastic jugs to keep air out + eliminate spilling. Easier when alone. Cheap master cylinder funnels prevent pulling in air and the need for up and down to refills.

#3)My favorite method was with the vacuum pump, hose & gage set up I had years ago. Again, another super easy way for one man job.
*note* these days one can find just a ton of "one man + simple" to use brake bleed kits. From as cheap as can be , all the way to as much as you want to spend. That is if you like to collect tools you wont use very often as I once did. I been giving lots of my old tools to all the younger guys in the family since I can't use them much anymore. The young guys love to get a hold of some long lasting/well used tools for free. I pay them for doing jobs for me and always manage to send them home with some type tools they can put to use.
 
System does not recirculate, so exchanging the master doesn't impact the calipers. YMMV but IMO it doesn't do anything.

That said, I've had calipers seize despite changing fluid. I'm in the camp of, it doesn't extend the life of calipers. Exchanging so as to have fluid that doesn't boil, or damage the master, good thing--but for me, in my salty clime, it doesn't matter.
 
What I've been doing for years on end is this: TRY every 2 years : 4 wheel disc brakes: pinch off calipers hoses, compress piston and get the junk out thru bleeder. Close bleeder. Move on to next wheel, repeat, and so on until all 4 are done. Start with RR caliper, then LR, then RF, then LF......gravity bleed. Pump up system with brake pedal. Then final gravity bleed : RR. LR, RF,LF, Done....... Takes a while, but I'm retired. Brakes always seem to work better and have yet to have a seized caliper. Use DOT 3 or 4 synthetic fluid. Not the fastest way, but I kill an hour or so. Have a climate controlled garage, so slow cold fluid is not a problem. Pedal always at the top., & never spongy when finished.
 
Last edited:
Pinch a brake hose? sounds like a bad idea. I would think that having the bleeder open would be good enough to not push fluid back up the line.

It’s not a bad idea though, could even go a step further: pull caliper off rotor, put in a stop, and pressurize the system so as to push the piston out further. Then open bleeder and crank in. This would also test the caliper to see if it is going bad—if it pushes in hard, it will seize someday soon.
 
Yeah, it's a bit neanderthalish, I could collapse the interior of the hose. I think I will go with supton's idea instead. :) But, I am familiar that if the piston pushes in hard, it's time for a new caliper. a semi-seized caliper will just hang up on the brake pad, causing pre-mature wear and warping. I always go back with OEM calipers. Had too many re-man'd and " new", ( highly doubt they were), start leaking from the piston seals. Not liking doing double work :(
 
Rat407 said:
Poor mans brake fluid change. Been busy and with this heat here in NC I don't care to be outside much. I hate it when i have to change clothes several times a day because I soak them with sweat. Anyway, is it worth sucking out the brake fluid out of the reservoir and filling back up with fresh every few days to get some fresh fluid in the system until I can bleed each wheel properly? I usually do it when I replace my brake lining but at the rate I'm going that will be years from now since I don't put the miles on like I used to. I wish they wouldn't have banned ATE Super Blue brake fluid. It was nice seeing blue fluid come out an knowing for sure it was fresh at each wheel.
Click to expand...
Brake fluid doesn't "move" other than the movement of the caliper piston or drum brake secondary cylinder. The fluid in the brake caliber/drum secondary cylinder remains there unless its drained.
 
3800Series said:
Not particularly, I don't know of any system which circulates the fluid so everything in the master cylinder typically stays in the master cylinder. Its the calipers which really matter and that fluid shouldn't make it's way there unless bleed.

That said the fluid does absorb moisture so it could in theory slightly lower the moisture content of the fluid overall but to what degree is a complete guess.
Click to expand...
stay in master cylinder and not circulate? Then how does fluid get dark with seal wear particles etc. (coming up from calipers) ?
 
willbur said:
stay in master cylinder and not circulate? Then how does fluid get dark with seal wear particles etc. (coming up from calipers) ?
Click to expand...
Wear from the master cylinder seals. In no way, shape or form does brake fluid circulate through the system.
 
I somewhat have to agree with Wilbur. There has to be a little circulation somewhere, or the fluid would not keep coming back dirty after a turkey baster job on the master only. I've done 3-4 turkey baster master only jobs in a row, ( a week apart), and the fluid kept coming back dirty. Kept it up until it stayed clean. Granted, the BEST way is a full 4 wheel bleed, but sometimes, you just don't have the time to go thru all of that. Life gets in the way of things. SOMETHING is better than nothing,
 
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