Brake fluid replacement

[bildr]

Can anyone tell me why BMW says that my brake fluid should be replaced at the 4 year service. It only has 30,000 miles on it and I hardly ever even use the brakes. Seems like a waste.

 

[TOEd]

In my experience the 2 year interval recommended by the dealer for our ev is a waste.
In the old days we never changed brake fluid. It was only flushed during a brake job. To this day many older guys refuse to do this preventive work.
https://bottomlineinc.com/life/car-main ... d-of-flush
Corrosion inhibitors in brake fluid must be pretty good these days. Voltmeter test is based on principle of galvanic corrosion that occurs in presence of moisture, a reading of less than 0.3 volts is ok when measured between negative battery terminal and the brake fluid reservoir. This voltage is temperature dependant so I would err on the side of caution in cold weather. I tried this on my 2013 Honda CRV (reading was 0.020 volts) and my 2015 BMW i3 (reading was 0.012 volts). Low values indicate that brake fluid is very dry. Brake lines on Honda were bled during brake job that I performed last summer. Dealer bled brakes (for free) last Fall.

 

[vreihen]

Brake fluid is hygroscopic, which means that it absorbs water from the air. Estimates are that it absorbs 2-3% water per year. Water doesn't compress as well as brake fluid, and also causes corrosion in the system. If it was better or the same as brake fluid, trust me the manufacturers would be filling brake reservoirs with water to save a penny! It is also why you should never use the contents of a previously-opened bottle of brake fluid to top off your car.

In a normal car, the brakes generate heat with every stop. That heat helps to boil some of the water out of the brake fluid, since water has a lower boiling temperature than brake fluid. Manufacturers who specify fluid change intervals on ICE cars frequently use 3 years, regardless of mileage.

On an EV, regenerative braking limits the waste heat that boils the water out of the fluid when you're not using the brakes hard. The BMW-specified two year change interval regardless of mileage sounds reasonable to me!

Given that the two year brake fluid change is the only scheduled maintenance on the BEV model that I know of, it isn't exactly going to break the bank to pay for this service every two years. This and the scheduled two-year dealer inspection cost me a smidge over $300 last month when I paid out-of-pocket for my new-to-me 2015 i3's scheduled fluid change. I'm afraid to look up the cost of a replacement ABS pump, to see how much it would cost me if it was damaged due to corrosion from water in the fluid.....

 

[jadnashuanh]

Brake components are expensive especially the ABS controller/pump. Moisture can cause things to corrode from inside. Preventive service is a good idea, and a staple of German tech. As noted, the moisture absorption is constant, and moisture is the culprit for that corrosion. Best to avoid that by replacing it on a timely schedule. It has no relationship with the miles driven, it's time. The boiling point also drops as moisture is introduced. This could be a big issue if you live in hilly or mountainous areas. Ignore at your own risk. There are tools you can use that can measure the moisture content, and you could use that to determine if it's time to replace the stuff. There are also test strips that can measure other problems.

 

[Srivenkat]

I am curious about the difference between brake fluid in an unopended can and the same in a sealed brake system. Specifically I would be interested to know if there are points of entry for moisture to enter the brake system. Or could moisture creep into an unopened can as well over time? I heard some cars have a rubber lid that can expand into the tank as the brake pads wear to prevent moisture from entering the system from the air that would be sucked in otherwise. Does the BMW brake reservoir use such a rubber lid? Thanks in advance.

 

[jadnashuanh]

While lots of the brake system is metal, there are some rubber components (seals) and some sections of flexible rubber hoses. Any rubber seal or hose can let some moisture into the system. The brake fluid REALLY likes water...it will suck it through the rubber. That's one reason why they always tell you to only add brake fluid from a new, unopened can...once you open it, you'll likely never reseal it well enough to prevent that action from happening.

 

[i3Alan]

Brake fluid is hygroscopic, which means that it absorbs water from the air. Estimates are that it absorbs 2-3% water per year.

Does it make any difference if the year-round climate has an average humidity well over 50% (most of the eastern US) as compared to the Sonoran desert surrounding Phoenix where the average humidity is 10-20%? That is, if a 2 year flush is enough for New Orleans, wouldn't a 4 year flush interval be more than enough for Phoenix?

 

[jadnashuanh]

Brake fluid is hygroscopic, which means that it absorbs water from the air. Estimates are that it absorbs 2-3% water per year.

Does it make any difference if the year-round climate has an average humidity well over 50% (most of the eastern US) as compared to the Sonoran desert surrounding Phoenix where the average humidity is 10-20%? That is, if a 2 year flush is enough for New Orleans, wouldn't a 4 year flush interval be more than enough for Phoenix?

Maybe, but is it worth the savings? Cost is less than $100 done at a BMW dealership, and probably less elsewhere. I think you'll find that the cap on the reservoir tends to let air in, but not out easily, so heating up the fluid to drive off moisture, at least in a non-track situation, probably isn't a big factor...once in, it stays in. It needs to let air in to compensate for the level dropping as the brake pads wear...not very fast in the case of the i3!

AT least in the USA, that service is covered at least once during the free maintenance period.

 

[Srivenkat]

Especially with the rest of the vehicle being rustproof (CFRP, etc.) and long-lasting, I would be inclined to maintain the brake lines well. I would be looking to get twice the life of a normal (metal) car out of this, with a battery and strut/spring upgrade at some point, as needed.

 

[PBNB]

Mine is due this month as well.

I bought an extended warranty so I guess I had better make sure it gets done to avoid any issues.

 

[stumbledotcom]

The two-year brake fluid replacement is required maintenance for all BMW models—not unique to the i3. Also worth noting that the two-year sequence starts with your vehicle’s manufacture date not the in-service date that triggers the warranty/maintenance plan period. My E90 3–series was assembled in February but I didn’t take delivery until September. As a result, the first two brake fluid services were covered at no-charge. The i3 requires so much less service that this one item takes on added importance. The two-year mark was the first time my ‘17 BEV went in. They did a bunch of software updates and the standard vehicle check as well. For me, it’s well worth going to a location that has full access to BMW tech bulletins, recall notices, etc.

 

[i3Alan]

Maybe, but is it worth the savings? Cost is less than $100 done at a BMW dealership, and probably less elsewhere. I think you'll find that the cap on the reservoir tends to let air in, but not out easily, so heating up the fluid to drive off moisture, at least in a non-track situation, probably isn't a big factor...once in, it stays in. It needs to let air in to compensate for the level dropping as the brake pads wear...not very fast in the case of the i3!

AT least in the USA, that service is covered at least once during the free maintenance period.

My '14 came with a 4 year warranty, so the break flush was done twice under warranty. I asked what the next one will cost me, and was told about $250 (including their free safety inspection, car wash, and lounge coffee). The question is not whether it is worth the savings, but whether the service is helpful at all more often than say every 3 or 4 or 5 years in Phoenix. There is a difference between saving and wasting money. I was thinking every 3 years might good, and probably more than useful.

On the other hand, I don't know if I can go 3 years between car washes.

 

[Anonymous]

I was thinking every 3 years might good, and probably more than useful.

Some manufacturers recommend every 3 years, some every 2 years. For BMW even their ICE cars, the recommended interval is every 2 years. As far as cost after the 4 year free maintenance agreement (not the 4 year warranty) has expired, you can purchase additional years of maintenance. BMW 'says' that by pre-paying for additional years' service, you can save up to 30% from what you would spend paying at the time of each service over the year. That may be a stretch, but my figuring, you'd at least be at break-even, if not ahead - at least with a Rex. Alternately you can find an independent BMW service garage, and have it done for less, because all they will do is flush the brakes and put in new fluid - no charging systems check, no software update, no 24 hr BMW Roadside Assistance, and no BMW Dealership mark-up, etc. A local independent shop in my area which only services BMWs, run by two BMW-trained former dealership master-mechanics, charges $100 to do a brake flush.

 

[jadnashuanh]

If you only ask them to do the brake flush, my BMW dealer gets about $80 for that. You can probably get it done in a independent garage for less. While you might want them to check the rest of the car out, a lot of the stuff they check, you can yourself. If there's a fault light, then, I'd want them to look at it if I couldn't identify the source of the problem myself. My dealer will give the car a once over each time it comes in. Probably not as detailed as what they were offering. FWIW, my dealership washes and vacuums my cars each time regardless of what it came in for. Not all are created equal.

 

[Badasblkbmwx5]

I was quoted $266.00 plus tax and hazardous waste fee. That would put it over $300. I rarely use my brakes, as the regeneration braking is so effective.

This is so overpriced. My son, a tech sad it was way
overpriced.... he would be glad to service it but cannot reset the computer. Said it literally a 10 minute job.

So sad as I need this service to keep my warranty.
I am taking it an Indy and have them reset the computer.

 

[jadnashuanh]

Resetting the computer is easy. Do a search for how to get into the service menu - you'll need your VIN. My BMW dealership charges about $80 or so for the job. IT works best to use a pressure system as pumping the brake pedal can stress the seals when you get to the bottom of the stroke which, under normal circumstances, is never reached and gunk up some things.

Whether you use your brakes or not, it's the fact that the fluid absorbs moisture through any of the rubber seals/hoses. This can promote corrosion of things that can get REALLY expensive, and, worst case, it lowers the boiling point of the fluid, so you could lose them. That last part may not be very likely with the regen braking, but is quite true for most any 'normal' car. FWIW, it's every two years from the date the vehicle was built, not necessarily when you bought it.

 

[Timjohn]

It is so disappointing to hear stories like this. Probably in reality not just BMW but across the board. I would invest in some tools, use whatever means to educate myself on how to do it myself and plunge into the task myself but that's just me. When I took delivery of my 2020 they offered me an extended warranty for about $3000 but with 4 years already, I decided to not to take it. I know after reading lots on this site and others that there are some very expensive components that could fail on the i3. But on the other hand, over all the reliability of the i3 is also well documented.

 

[FiremanDan2928]

Extended warannty

I want to let everyone know that BMW makes an exceptional complex vehicle. I have owned many since my first 1983 320is.

For so many reasons, I totally recommend purchasing an extended warranty. My X5 was purchased as a CPO. I didn't experience many
issues, as it was new. Fortunately, I had purchased an additional 48 month, 48k warranty, that would start once the CPO expired. What a GOD send!

The tows, car rentals and repairs, far exceeded the $4500 warranty. I had so many things that wore out, and were covered.

At 140K miles, our X5 still drives like new. The entire suspension was replaced, all the infamous oil leaks, all covered under warranty. Had I not had an extended warranty, I woud had replaced her several years back.

At this point, our car has been paid off for quite some time and many other the common problems/ issues have been addressed. We are planning to keep her till she turns10 and replace her with an S drive, (rear wheel drive), as I live in south florida. I would buy another CPO X5 and again, purchase an extended warranty.

 

[spartacus68]

The brakefluid change is straight forward and I do it every 2 years starting with the wheel furthest from the brake reservoir. My wife's 15-plate i3 REx is outside warranty now so I do the maintenance, including the oil and filter changes, and as they say prevention is the name if the game given BMW costs if it goes wrong.

FiremanDan, my brother has an 3.0 TDI V6 X5 (2006). It's basically a truck. Everything is huge from his current road tax bill £500 a year) to tyre replacement - don't ask! I have to use a small step ladder to access the air filter which is buried at the back of the engine in the most inaccessible place. It's old technology compared to the i3, a bit like a T-REX staring at an incoming meteor! These kind of cars are heading for extinction on this side of the pond, and although petrol prices are low just now they will creep back up again.

 

[jadnashuanh]

I had one car, quite a long time ago now, that did not recommend changing the brake fluid on a timed basis...the antilock brake actuator failed...cost over $1200, and that was like 40-years ago. Had another car, again, didn't recommend that sort of thing...the brake lines rusted out from the inside.

It's cheap insurance to change it. The issue is, the rubber components will let some moisture in. This decreases the boiling point of the fluid, and can lead to corrosion...neither of which is a great thing in something as critical as brakes and being able to stop!

It's along the same idea of replacing your tires after 5-years or so...the rubber ages, so even if there's a lot of tread left, they will not perform as they should - they get harder with less capacity to grip, and the rubber can check, and leak air faster, or fail, as it can expose the cords to moisture. Some things are mileage related, some are time related.