When do you replace brake fluid?

Discussion in 'Kia Niro' started by Texas Niro EV, Apr 8, 2021.

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  1. Texas Niro EV

    Texas Niro EV Active Member

    I would venture to say that there are many cars out there that are decades old that have never had a brake fluid change, I've got one sitting in my driveway. I'm sure a great many cars go from manufacturing plant to junk yard without a single brake fluid change. Neither the Niro EV owner's manual or service manual even mentions regular intervals for brake fluid replacement.

    Both the Niro EV owner's manual and service manual do identify regular intervals for "inspecting" brake fluid. Basically "inspecting" the brake fluid means taking the top off the master cylinder and looking at the brake fluid. In addition to verifying the fluid level you have to look closely at the color.

    The worse thing that can happen to the brake system fluid is for someone to put in the wrong type of fluid. The wrong fluid is detectable by two different colors in the fluid. The wrong fluid will react with all the rubber components of the brake system and you will have to disassemble all the brake system components and replace all the O-rings, rubber plungers, etc.

    The second worse thing is water contamination. Water contamination will be evident by a milky color brake fluid. Water contamination is usually corrected by replacing the master cylinder cover gasket and flushing the brake system.

    The least worse thing that can happen to brake fluid is just old age. When brake fluid is new, it is clear or almost clear but the fluid gets darker as it ages. If your brake fluid is very dark you may want to replace it.

    So if you take your car into the shop and the shop recommends brake fluid replacement, be wary. Do your own brake fluid "inspection" and see if you concur with the shops diagnosis. It sure wouldn't hurt to know a little about what good brake fluid looks like and it may just save you an unnecessary charge at the mechanic shop.
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  3. ENirogus

    ENirogus Active Member

    If you plan on keeping a car, flushing the brake fluid every 4 or 5 years is a good idea. A car gets frozen calipers due to rust. Rust comes from water in the fluid. Any newer car with ABS one must be careful not to get air into the system or you may need to bring it to the dealer to bleed.
    If you are not keeping a car for more than 5 years, it is not that important.
    All US cars use compatible brake fluid since the 1970s
    if you have an air compressor, a few bucks in parts can make a pressure bleeder. A spare cap with a hole drilled in it and a tire valve stem, or specially made pressure cap, a regulator for a spray gun and a turkey baster. Empty the reservoir with the turkey baster and refill with new fluid. Set the regulator for 10psi or less. Screw the cap on and walk around and bleed all 4 calipers. a short length of hose that fits on the bleeder keeps it neat, or a rag. Monitor fluid level in the reservoir and top up as required.
    IF you accidentally let in air from the top, take a caliper off and push the piston back, this will push fluid back into the reservoir and keep air out of the abs pump. REmember to then pump the brakes until the pedal comes back after replacing the caliper, as that brake caliper will need to be refilled

    Unless you are racing or have some reason to believe that your brake fluid is especially contaminated there is no reason to worry about getting every last bit of old fluid out.

    Shops have computers that can cycle the ABS pump and make flushing easy, so if a mechanic gives a reasonable price for doing it[perhaps while doing brakes] let them do it.
  4. snowy2020

    snowy2020 New Member

    Last edited: May 5, 2021
  5. snowy2020

    snowy2020 New Member

    I'd love to know what happened between 2019 and 2020.

    Suddenly the coolant for the 2020 needs to be replaced every 37k instead of 120k? That's a huge difference. Suddenly the brake fluid needs to be changed every 30k?
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  7. Hedge

    Hedge Member

    Because they needed to increase the revenue from maintenance items on EVs to keep the dealerships in business.
    ENirogus likes this.
  8. ENirogus

    ENirogus Active Member

    Could be the coolant corrosion inhibitors are not working as well as they had hoped
  9. I just had my 2019 serviced at the 15k interval. They said the brake fluid was "discolored" but didn't need changing....yet.
    This was a surprise to me since I am pretty sure I rarely have braked hard enough to engage the calipers much, with region doing all the work (or nearly all...I suspect the last few mph of velocity HAVE to use the physical brakes since the emf generated by turning the motor gets smaller as the speed drops which would result in a lower and lower delta momentum per unit time (aka braking force), but how much wear and tear is that really going to cause.

    Does essentially unused brake fluid change color over time, even just sitting there more or less unused?

    Additional data point. The inspection claims my pads were 7mm thick. I don't know the thickness of new OEM pads on the Niro. A quick google search implies new pads can vibe anywhere from 8-12mm thick. Even if they started at 8mm, losing ~1% per 1000 miles seems a lot considering my Prius only needed new pads after a couple hundred k. If they are thicker than 8mm to begin, this becomes even harder to believe.

    The service center ALSO failed to rotate my tires like I asked (well, they did not bill me for that step and I doubt they would have forgotten that!) AND they gave me a courtesy wash which I specifically asked not for them to do since I had a meeting to get to (sure enough, they said my car was ready, I pay and then wait outside for 20 minutes because "it was being washed") . I think I will try a different dealer service center next time. smh

    Has anyone purchased OEM pads ? I imagine a maintenance manual also has starting pad thickness.

    Last edited: Sep 12, 2021
  10. ENirogus

    ENirogus Active Member

    I wonder if our pads will wear faster through disuse. IOW rust buildup might wear them faster than mild use

    brake fluid in the reservoir is always discolored from environmental factors. It is really time not use.
    Kinda sad they won't just bleed them through at least.
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  12. snowy2020

    snowy2020 New Member

    Wait…so what DID they even do? Rotating the tires is the only actual service you needed and they didn’t do it, so what did you pay them for?
  13. The tire rotation was an extra fee which they did not charge me for. There is a set labor cost for the 15k inspections so that was most of it. They also replaced my cabin air filter. Probably needed it after all the smoke I was driving in last month. I know they also ran some sort of battery health diagnostic.

    I would have to get the sheet to tell you all the inspections they did to give you the full list. Let me know if you are interested.

    I did not realize the air filter would be extra. I will go to pep boys and do it myself the next time.

    I am not big on the regular service interval thing and skipped the 7500 mile one. I am mostly concerned about the reduction gear fluid, and wanted that inspected, what with all the trouble too many folks have had with their motors. Maybe the problem starts dumping metal shavings in there or overheating it. Otherwise, that should be good for quite a while.
  14. Texas Niro EV

    Texas Niro EV Active Member

    I have almost 40k miles on my Niro EV so I decided to try to change my brake fluid. I couldn't get any fluid to come out. I was trying to use a vacuum systems but my service manual says I need to use a pressure bleed system and then it says I have to perform the "Fluid Circulation Mode" by KDS.

    Has anyone replaced their brake fluid yet and, if so, did you replace the fluid yourself or have the dealer do it?
  15. why? Just on principle? Most braking has been via inductive coupling between the wheels the motor and the battery, do it is unlikely up your fluid has ever been hot.
  16. Well, since you've had no answer I'll mention that the dealer did this job on my Kona at the second service per the manual. Afterwards I checked that each wheel bleed fitting showed evidence that it was done, which they did. I suspect they have a machine that forces fluid through from the master cylinder and presumably have to use their computer to manipulate the many valves and the 2nd electro-hydraulic cylinder that provides pedal feel without actually applying the brakes. Now that my EV is out of all warranties except the battery, this will be the one service job I will have them do every two years even though I've always done this sort of maintenance myself.
    The main reason to do it is because it's called out as a maintenance item. Heat has nothing to do with it but drawing moisture through the vented cap does. Looking at how complicated and expensive the entire system is and that it's in use whenever the pedal is pushed (irrespective of whether braking is by regen or disks), I think it's the right call to follow the manufacturer's recommendations.
  17. ITown

    ITown Active Member

    Just curious, how much did the dealership charge for the air filter replacement? And which dealership?
  18. Texas Niro EV

    Texas Niro EV Active Member

    The service schedule for the 2020 Niro EV recommends replacing the brake fluid every 30k miles. I just had to replace the brake calipers on my 2004 GMC Envoy that has only 87k miles because the calipers had seized up. Maybe the calipers would have lasted longer if the brake fluid had been changed more often.
    KiwiME likes this.
  19. ENirogus

    ENirogus Active Member

    it is not about use, it is about absorbing moisture which is more related to time than mileage
  20. Paul K

    Paul K Active Member

    For non EV specific stuff I take mine to the same shop that has services my ICE car. I've dealt with them for over 30 years. When I get my seasonal tire changes I usually ask them to clean and lube the brake calipers before the winter tires and rims go on. With the amount of road salt used here this is a must. With EVs the problem is even worse as the brakes don't seem to get hot enough to dry out.

    My mechanic charges around $70 to perform this service. The dealers? $240. Go figure. In the past I have had brake calipers seize up on my ICE cars but since I started requesting this annual service have not had a problem.
  21. I'll add something else to this somewhat dreary subject, our shared brake master cylinder costs around US$2500 at a parts supplier, twice the cost of the gear reducer that could benefit from preemptive rather than just scheduled maintenance.


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