Brake system flush

Whats a good cleaner for flushing brake system ? I have started draining and overhauling brake calipers and need something to clean system before refilling.

Thanks

Just keep pushing that brake fluid thru there until it comes out clear.

"Dot 3 from a sealed container" as they say.

I use common household rubbing alcohol for cleaning disassembled master cylinder and caliper parts.

The squeeze type sprayer nozzle from a squirt bottle fits onto a plastic bottle of rubbing alcohol, and works well for this purpose.

Alcohol may be squirted through the brake lines (detached from master cylinder and caliper) if deemed necessary, followed by compressed air.

Parts, and lines, should be blown with compressed air to remove residual alcohol, and dry them.

Lightly coat master cylinder piston and caliper piston with fresh new brake fluid before reassembling.

May attach a short length of plastic tube to the bleeder valve nipple, and use a new bulb syringe to refill the system by injecting fresh fluid through the bleeder valve.

The normal routine maintenance "flushing" of the brake lines to "change" the fluid --- usually entails only removing most of the old fluid from the m/c (try to avoid exposing the supply holes at bottom of reservoir to air). Then keep the reservoir topped up with new fluid while steadily pumping it through the system to waste from the bleeder valve, until eventually, new fluid appears from the bleeder valve.

Good Luck!

I know this is gonna stirr up a hornets nest, but , I have used carb cleaner followed by compressed air to clean everything out of the lines.
Then, I use dot 5 fluid, I have had it in the rear brakes on the 1000 now for about 2 plus years and a friend had it in his entire brake system for 10 and never had any issues.
So I am gonna stay with the dot 5 when I clean or rebuild the brake system

suck out all the bad stuff in your master with a syringe and wipe out all the left over goo with a paper towel then take the same syringe and put it on the bleeder fill up your master cylinder then crack the bleeder and start sucking out the old brake fluid out of the caliper and lines always keep an eye on your level in the master top up as needed. that will fillthe system with fresh fluid and not allow any air in to the system.

Just flush with DOT-3 until everything comes out clear.

I'll second or third the push the DOT 3 through until it comes out clean. A related question, how do you guys clean the sight glass in the front master cylinder that has old nasty stains on it? Thanks.

grumpy56 wrote:

I'll second or third the push the DOT 3 through until it comes out clean. A related question, how do you guys clean the sight glass in the front master cylinder that has old nasty stains on it? Thanks.

I used a nylon broom bristle(the fuzzy end)and a drop or two of oven cleaner first and after a minute or two I followed up with alcohol to rinse. I stuck the fuzzy end in the slot and made it flex while spinning it in my fingertips. It worked like a charm, rubbed all the discoloring right off!

BSKZ650 wrote:

I know this is gonna stirr up a hornets nest, but , I have used carb cleaner followed by compressed air to clean everything out of the lines.
Then, I use dot 5 fluid, I have had it in the rear brakes on the 1000 now for about 2 plus years and a friend had it in his entire brake system for 10 and never had any issues.
So I am gonna stay with the dot 5 when I clean or rebuild the brake system

I thought many carb cleaners aren't friendly with rubber parts, what brand do you use?

I your using a pressure bleeder, DOT5 is ok.
DOT5 is slightly more compressable, and actually has a lower boiling point than DOT4.

DOT5 is doesnt eat paint though... nor does it absorb water...

I think DOT5.1 is the way to go.

The fact that DOT-5 doesn't absorb water is one of the problems with DOT-5. DOT-3 and DOT-4 are hygroscopic (they absorb water) so any water entering the brake system is fairly evenly distributed throughout the fluid. DOT-5 does not absorb water, so water that enters the brake system collects as "puddles" and will rust or rot areas where it collects. Racers use DOT-5 in non-ABS systems for the higher boiling point which may matter for heavy-duty repetitive track braking. However, on the street you do not need to worry about boiling the brake fluid because you don't build up the heat from repetitive extremely hard braking. Pro racers change their brake fluid very often, so water "puddling" is not an issue for them. Some folks here swear by DOT-5, maybe they live in dry climates? Check the other threads on this site and check the internet before deciding on DOT-5. See how many bike or car manufacturers you can find that recommend DOT-5 (even in high performance street machines). If you do switch to it, remember it is NOT compatible with DOT-3 or 4, so you need to figure out how to COMPLETELY purge all traces of DOT 3 or 4 from your system before switching. Ed

rayellis wrote:

Whats a good cleaner for flushing brake system ?

clean brake fluid