DIY brake fluid replacement without expensive tools?

[C02less]

I would like to replace my brake fluid (as I have on other cars many times) on my 2021 Kona EV, but without buying an expensive scan tool to control the ABS and parking brake.

I found a reference to KiwiME's gravity bleed method here: https://www.insideevsforum.com/comm...led-maintenance-costs.9234/page-4#post-106065 Is anyone doing this on their Kona EV to replace (most of) their brake fluid?

Any other recommended methods without $pecial tool$?

Thanks
Don

 

[C02less]

OK, so 5 minutes after posting I saw this article: https://www.brakes-shop.com/brakepedia/general/bleeding-anti-lock-brakes

The gist of it is: if you bleed the brakes conventionally with cheap tools, like my trusty mityvac, you will not remove all the old fluid. When you use the ABS (or EPB?) you will mix a little old fluid with the new to make it 75% new. Or, you can invoke the ABS by skidding then replace the brake fluid over again to make it 95% new. Or, like KiwiME suggested just flush and replace the fluid once, but do it every year. The point is to minimize contaminants in the brake fluid and not let them linger where they can cause more expensive problems like internal corrosion.

Any feedback by those who have actually done a brake fluid replacement on their Kona EV?

 

[C02less]

Another forum participant sent me a pdf of the factory air bleed procedure, and surprisingly, it does not require a special tool to manipulate the Kona's ABS. It's not the same as a full fluid replacement but it gives some clues for how to work around Kona's ABS etc. Unfortunately, the procedure couldn't be uploaded as a pdf so here's my summary:

First: disconnect the negative battery terminal and bleed the system with a pressure bleeder at 43-51psi for 15 seconds per corner, refilling the master cylinder as required. (my opinion: At that kind of pressure it should blast copious quantities of brake fluid right out in 15 seconds and could replace all the fluid in the lines and master cylinder, especially on the front brake lines).

Next: (cut and paste from factory manual, there were no pictures)
Pertform the air bleeding mode. Air bleeding mode Prcoedures 1) Set the front wheels straight forward and the shift lever knob in Parking After with the vehicle on. 2) Hold the ESC OFF switch and operate the brake pedal 10 times in full stroke. And then turn off the engine. • When stepping on the brake pedal, press 40mm or more, and when releasing it, press down 10mm or less. • The ESC OFF switch must be held down until the pedal operation is finished and the engine is turned off. 3) Start the engine. And then press the ESC OFF switch for more than 3 seconds to enter ESC OFF mode. • When entering the Air Bleeding Mode, it is possible to check whether you entered the mode by checking the illumination of the ESC OFF lamp, EBD/ABS lamp and parking brake/brake lamp. (Check whether you entered the Air Bleeding Mode through the lamp before starting the additional work. If the lamp is off retry to enter the Air Bleeding Mode.) The brake warning lamp turns on if you start the air bleeding work without entering the Air Bleeding Mode. Air bleeding mode Release 1) Igniton OFF and shift lever knob in D/R/N 2) Detecting DTC 3) ESC off mode released

Finally: have an assistant help you bleed the brakes the old fashioned way by pumping the brake pedal. (my opinion: why would you ever do that if you have a pressure bleeder? In my experience a pressure bleeder or vacuum bleeder always better than the marriage tensions that arise when I get my assistant to help, lol).

 

[electriceddy]

Another forum participant sent me a pdf of the factory air bleed procedure, and surprisingly, it does not require a special tool to manipulate the Kona's ABS. It's not the same as a full fluid replacement but it gives some clues for how to work around Kona's ABS etc. Unfortunately, the procedure couldn't be uploaded as a pdf so here's my summary:

First: disconnect the negative battery terminal and bleed the system with a pressure bleeder at 43-51psi for 15 seconds per corner, refilling the master cylinder as required. (my opinion: At that kind of pressure it should blast copious quantities of brake fluid right out in 15 seconds and could replace all the fluid in the lines and master cylinder, especially on the front brake lines).

Next: (cut and paste from factory manual, there were no pictures)
Pertform the air bleeding mode. Air bleeding mode Prcoedures 1) Set the front wheels straight forward and the shift lever knob in Parking After with the vehicle on. 2) Hold the ESC OFF switch and operate the brake pedal 10 times in full stroke. And then turn off the engine. • When stepping on the brake pedal, press 40mm or more, and when releasing it, press down 10mm or less. • The ESC OFF switch must be held down until the pedal operation is finished and the engine is turned off. 3) Start the engine. And then press the ESC OFF switch for more than 3 seconds to enter ESC OFF mode. • When entering the Air Bleeding Mode, it is possible to check whether you entered the mode by checking the illumination of the ESC OFF lamp, EBD/ABS lamp and parking brake/brake lamp. (Check whether you entered the Air Bleeding Mode through the lamp before starting the additional work. If the lamp is off retry to enter the Air Bleeding Mode.) The brake warning lamp turns on if you start the air bleeding work without entering the Air Bleeding Mode. Air bleeding mode Release 1) Igniton OFF and shift lever knob in D/R/N 2) Detecting DTC 3) ESC off mode released

Finally: have an assistant help you bleed the brakes the old fashioned way by pumping the brake pedal. (my opinion: why would you ever do that if you have a pressure bleeder? In my experience a pressure bleeder or vacuum bleeder always better than the marriage tensions that arise when I get my assistant to help, lol).

ESC OFF switch? Is that the one on the lower panel to the left- electronic stability control?

 

[KiwiME]

Yes, that's the button.
It's such a complicated procedure (much like others in TSBs) that it's no wonder Hyundai techs have the thousand-yard stare.
And the pressure specified seems positively horrifying regarding the plastic reservoir structure.

I can't see myself trying it as-written. For decades I've used pressure bleeding but the last time I did my ICE car I used vacuum on the four corners and frankly found that easier because it was more controlled, less risk of a mess and far more convenient to add fluid with the reservoir cap off.

Two possibilities to move forward are to (1) rewrite the procedure with just the main steps so it's easier to follow, or (2) try out a vacuum bleed at the slight risk of drawing in air, noting that I have no evidence to suggest that this would happen. If the latter can be proven safe, despite not catching all the fluid doing that once every 12-18 months has got to be the easiest path for us DIYers.

 

[C02less]

So I did the vacuum bleed like I would on any other car. I was only able to replace about half a litre of the brake fluid this way. Two of the calipers let me bleed a little fluid and two almost nothing. I probably got most of the fluid out when I used my vacuum bleeder to remove some brake fluid from the reservoir. The old fluid was still very light in color, but I did notice that after a few days it darkened slightly in the master cylinder reservoir, indicating that the new and old fluids were mixing. So the old fluid was being improved by diluting it with new fluid.

I didn't notice any difference in pedal feel afterwards, so it's not likely any air got in. I had a chance to drive a brand new Kona back to back with mine and the pedal feel was about the same. I always though that the brake pedal on a Kona was a bit mushy, but it's no porsche and I wasn't expecting that level of quality. Modulation is still excellent on the Kona.

Next time I will just bleed any air from each caliper and change the brake fluid in the master cylinder reservoir. I'll let the brake fluid circulate naturally through the system to dilute the old fluid with the new. Maybe get one of those testers to indicate how much water has been absorbed. Either that or let the dealership change my brake fluid (which really hurts my pride).

 

[KiwiME]

As it's been three years since the last (dealer) fluid change, instead of taking a walk or drive in the spring weather like a normal person I decided today was DIY brake fluid refresh day. I drew out the old fluid from the substantial reservoir, refilled with new and tried vacuum removal on the right-front wheel first, since I could reach it without lifting the car while keeping an eye on the reservoir.

I drew out a perhaps 50ml of surprisingly-clear fluid but didn't see any drop in the reservoir level, so closed it up and pumped the pedal gently a few times. The fluid level still didn't drop much but the pedal did pump up a bit and felt OK, as rubberey as usual. Obviously I was concerned that there was a 50ml air pocket somewhere - but more so about having to explain my idiocy to the dealer.

I then attempted the two procedures outlined in post #3 which produced some clicks and clunks, then went for a drive up and down some hills. Everything seemed normal and there were no warning lights or OBD codes.

I think I'm going to agree with @C02less, including that this is not straightforward and the fluid appeared clean enough that renewing the reservoir fluid perhaps every 1/2 to one year may be good enough and is way more practical on a DIY level. I'll grit my teeth and ask the dealer about the cost of a replacement cap so I can fit it with a pressure barb, as I normally do with my ICE cars. But given that they only charged me $80 for the flush job last time, it's hardly worth the trouble.

Next time I will just bleed any air from each caliper and change the brake fluid in the master cylinder reservoir. I'll let the brake fluid circulate naturally through the system to dilute the old fluid with the new...

Just before I went on my test drive I snapped a photo behind the wheel to see if there was any fluid spilled. Good thing I did...