Question on flushing/bleeding brake fluid

**Miles_on** · March 30th, 2023 01:33 PM

Old school mechanics used to siphon out the brake fluid reservoir while performing a complete replacement of a vehicle’s brake fluid. It’s increasingly common for most vehicles to have a fine mesh screen in the reservoir though that’s very difficult to remove. While this makes it difficult to siphon the fluid from the reservoir, I think its not meant to be taken out, so I’ll leave it as is.

Question-
Is it alright not to siphon the old fluid from the reservoir, and just keep alternately bleeding and topping up until all the old fluid has been replaced while doing a flush?

-I know mas time consuming and magastos ito, because you’ll need to use more new brake fluid than “the old way”, but baka masira ko yung screen if I try to remove it.

-I also don’t have any “hi-tech” tools, so I won’t touch the ABS system either.

Any thoughts/input?

**shadow** · March 30th, 2023 01:48 PM

Pagawa mo na lang sa shop na meron vacuum, less than 30 minutes na flush na completely yun brake fluid mo. It's like less than ₱500 lang ang fee.

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**Miles_on** · March 30th, 2023 02:14 PM

Madalas tinatangal nila yung screen kasi eh, tapos nabubutas/sira.

Wala pa naman mabili ata niyan, kadalasan set ata yan kasama yung buong reservoir?

Tangal screen din yung ginagawa ng tao ko dun sa mga truck namin (old school nga) so I figured ako na lang gagawa...

**12vdc** · March 30th, 2023 02:30 PM

Ganyan gawa ko DIY. Kung kaya punasan yung dirt sa filter much better.

Siphon the old fluid out, top-up. Bleed the front, top-up. Bleed the rear, top-up. Make sure fresh fluid gets into the bleeder valves.

Same din sa PS fluid. Siphon old, top-up, steer lock2lock then siphon, then top-up. Repeat, make sure new fluid circulated the pump and diluted old fluid.

Tools: 12V pump meron sa Deeco - use appropriate size aquarium or aerator hose. 8mm or appropriate size flare-nut wrench for the bleeder valve. 1.5L Softrink bottle to store old fluids.

**Flipo** · March 30th, 2023 03:03 PM

Originally Posted by Miles_on

Madalas tinatangal nila yung screen kasi eh, tapos nabubutas/sira.

Wala pa naman mabili ata niyan, kadalasan set ata yan kasama yung buong reservoir?

Tangal screen din yung ginagawa ng tao ko dun sa mga truck namin (old school nga) so I figured ako na lang gagawa...

Try this from YT:
How to do a Complete Brake Flush and Bleed

https://www.youtube.com/watch?v=n1NvtUwfRJc&t=566s

**yapoy86** · March 30th, 2023 03:32 PM

siphoning the old fluid sa reservoir is better.. hygroscopic yan kaya may moisture na yung nasa reservoir.. better remove it..

some ABS equipped cars, much better yung pump-stop-bleed na technique.. mahirap gamitan nung vacuum kasi restricted yung fluid sa ABS pump..

make sure na lagi puno yung reservoir during bleeding, mahirap pag pinasok ng air yung ABS pump.. need mo pa ng diagnostic tool dyan to let the pump cycle

**Vodka** · March 30th, 2023 07:41 PM

Originally Posted by Miles_on

Old school mechanics used to siphon out the brake fluid reservoir while performing a complete replacement of a vehicle’s brake fluid. It’s increasingly common for most vehicles to have a fine mesh screen in the reservoir though that’s very difficult to remove. While this makes it difficult to siphon the fluid from the reservoir, I think its not meant to be taken out, so I’ll leave it as is.

Question-
Is it alright not to siphon the old fluid from the reservoir, and just keep alternately bleeding and topping up until all the old fluid has been replaced while doing a flush?

-I know mas time consuming and magastos ito, because you’ll need to use more new brake fluid than “the old way”, but baka masira ko yung screen if I try to remove it.

-I also don’t have any “hi-tech” tools, so I won’t touch the ABS system either.

Any thoughts/input?

the purpose of sucking out the fluid from the reservoir is to make the flushing faster coz you don't have to pass all the old fluid in the reservoir through the lines

**jick.cejoco** · March 30th, 2023 08:04 PM

most asian cars have strainer/screen at the filler mouth of the master cylinder. this can be removed carefully for service. so far, i have not torn any screen. options removing the old brake fluid from the master cylinder include using a basting syringe, or vacuum, or you can modify a plastic catsup bottle and extend with a clear polyethylene hose that is readily available at hardware stores. with abs, it is recommended that the ignition key is on to activate the hydraulic pump. on some vehicles, there is what appears to be a master cylinder but it's not. the pressure comes from the hydraulic pump. when i do a routine two year brake fluid flush, i empty the master cylinder as much as i can extract fluid, then bleed the system according to whether it is diagonal split or front/rear split. compress the piston to expel most of the fluid inside then proceed with bleeding. for typical diagonal split, the sequence is 4-3-2-1(RR,LR,RF,LF). for diagonal split like nissans, 4-1-3-2 otherwise, follow the repair manual sequence.

on some cars with manual transmission with hydraulically actuated clutch release share the same brake fluid from the same reservoir. this clutch hydraulics has to be flushed too.

**Miles_on** · March 31st, 2023 09:46 AM

I agree naman it's better to get as much of the old fluid out of the reservoir (without letting it go completely dry of course!) but there didn't seem to be much space to even get a thin hypodermic needle in the strainer gap (puwang) in the fluid reservoir...

It doesn't seem to be a critical step though. It will just take longer nga lang to completely flush (imbes na tanggal na yung fluid na yun sa reservoir, you have to flush it out through the bleeder valves). Bleed - tapos top up na lang ng top up ginawa ko

(RR tire side, LR then FR & LR).

The ABS light stayed on mga 1 second longer than usual when I started it up, but went out. Normal naman na afterwards.
--->I'll try the suggestion to keep the ignition key on next time para madamay yung fluid sa ABS.

Drove it afterwards (road test) and again today, no problems.

Regular DOT3 lang ginamit ko. Its been an industry standard fluid naman na for mga 50 yrs na, so palagay ko any brand's fine. (P280 something per liter)

--- > I don't know if there's any truth in the rumors (urban legend?) of a cheap local brand ("S.B.") ruining your brake hoses daw in the long run, but palagay ko, hindi totoo yun. Usually kasi ginamit ata in a poorly maintained PUV that had a tendency to break down naman talaga no matter what.

**jick.cejoco** · March 31st, 2023 04:09 PM

on older volvo 240 dl, there are two brake hoses to the front left, two brake hoses to the front right and one brake hose each on the rear. talking about redundant systems, volvo has it. in 1965, the u.s. d.o.t. requirement for dual brake system was enacted. if one system fails, the other system is used as a backup, vice versa. but volvo took the cream.

(FVMVSS) federal Motor Vehicle Safety Standards paragraph 5.1.2.1