Question on Service Intervals

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I have done brake fluid changes every 2 years (with every other battery check). My dealer has usually offered a discount for doing both together. I notice a firmer pedal feel after each fluid change so it is worth the expense to me. Testing the fluid in the master cylinder may not give a true indication because that is the highest point in the system and water goes to the lowest point (generally the calipers). Since there is no "engine braking" from regeneration if the battery is fully charged, the friction brakes could get quite hot during a long downhill drive so moisture in the calipers could boil and cause soft pedal feel or loss of braking effectiveness.
 
SageBrush said:
gncndad said:
Replacing brake fluid is cheap maintenance, to protect all components from rust/corrosion. We all know brake fluid is hygroscopic, so time is as critical as mileage. I will stay with 3 year brake fluid replacement interval, regardless of mileage, based on many, many years of experience.
Your experience is with cars that do not use regenerative brakes

Are You disagreeing with the man?

Since the Leaf Has no maintenance to speak of, then it can only be smart to change the transmission fluid AND Brake Fluid every 40K miles. And if you do not drive a lot, change the brake fluid every 3-4 years. Everything is very cheap and it is nice to have nice clean fluids regularly.

If you disagree, that is your own business, but do not tell other Leaf drivers and non-mechanical people that it is not necessary....
 
Brake fluid is hygroscopic.
Regen doesn't matter.
The brake fluid is going to continue to absorb water, the brake system is make of steel and other dissimilar metals which will be eaten away over time.

The reaction between water, brake fluid and metals in the brake system will break down and form gases.

I sure as hell wouldn't pay a dealer to do it. Just suck the old brake fluid out of the reservoir with some sort of fluid sucking implement, wipe out the left over gunk in the bottom of the reservoir with a lint free shop paper towel, refill with fresh fluid from a factory sealed container, bleed brakes and refill as needed.

If anyone thinks the leaf needs no preventative maintenance like this then all I can say is ignorance is bliss.
 
Brake fluid is hygroscopic.
Regen doesn't matter.
The brake fluid is going to continue to absorb water, the brake system is make of steel and other dissimilar metals which will be eaten away over time.

Water usually enters the brake system through the reservoir. EVs tend to have much lower brake wear, so the brake fluid drops more slowly and the fluid level gets checked less frequently (except visually, through the translucent reservoir body) and the cap is removed less often. The end result is less water in the brake fluid. No one is arguing for zero maintenance, just that replacing the brake fluid every year (and even every two years) is usually unnecessary.
 
LeftieBiker said:
Brake fluid is hygroscopic.
Regen doesn't matter.
The brake fluid is going to continue to absorb water, the brake system is make of steel and other dissimilar metals which will be eaten away over time.

Water usually enters the brake system through the reservoir. EVs tend to have much lower brake wear, so the brake fluid drops more slowly and the fluid level gets checked less frequently (except visually, through the translucent reservoir body) and the cap is removed less often. The end result is less water in the brake fluid. No one is arguing for zero maintenance, just that replacing the brake fluid every year (and even every two years) is usually unnecessary.

All good points.
I will stay with 3 year changes in ANY hydraulic brake system, whether or not it has regen capabilities. CHEAP!!!!!
 
SageBrush said:
Ignore that useless battery check with the pride that comes from saving $100. Your warranty is safe without it.

Right on, Sagebrush. Stay away from a Nissan dealer for everything except items covered under warranty. There are much better ways to spend your hard-earned money.
 
Oilpan4 said:
Brake fluid is hygroscopic.
Regen doesn't matter.
The brake fluid is going to continue to absorb water, the brake system is make of steel and other dissimilar metals which will be eaten away over time.
I rely on the advice and teaching of a fellow who calls himself 'hobbit' on the internet (presumably related to his tendency to walk around bare-foot.) Make no mistake though, this guy is an MIT trained engineer and one smart dude. He is probably one of the top 5 Prius hackers in the world.

On the subject of brakes he writes (as part of his 100k maintenance)
On a slightly different tangent ... after 5 years, what state is the brake fluid in? Many people would expect it to be way overdue for a flush/replacement. There are numerous articles and posts floating around on brake fluid and its affinity for water and how the more water content it collects, the more likely it is to corrode internal brake system parts and boil into vapor under severe heating and cause spongy braking. The forums are full of self-styled "experts" telling each other that no brake fluid can possibly be any good after two or three years, and when the ambient babble gets loud enough one might be tempted to start believing it.
Not so fast, bucko.
The remainder of his investigation and conclusions are here:
http://techno-fandom.org/~hobbit/cars/maint100k/
Starting from the 'Brake Fluid' section.
 
SageBrush said:
Oilpan4 said:
Brake fluid is hygroscopic.
Regen doesn't matter.
The brake fluid is going to continue to absorb water, the brake system is make of steel and other dissimilar metals which will be eaten away over time.
I rely on the advice and teaching of a fellow who calls himself 'hobbit' on the internet (presumably related to his tendency to walk around bare-foot.) Make no mistake though, this guy is an MIT trained engineer and one smart dude. He is probably one of the top 5 Prius hackers in the world.

On the subject of brakes he writes (as part of his 100k maintenance)
On a slightly different tangent ... after 5 years, what state is the brake fluid in? Many people would expect it to be way overdue for a flush/replacement. There are numerous articles and posts floating around on brake fluid and its affinity for water and how the more water content it collects, the more likely it is to corrode internal brake system parts and boil into vapor under severe heating and cause spongy braking. The forums are full of self-styled "experts" telling each other that no brake fluid can possibly be any good after two or three years, and when the ambient babble gets loud enough one might be tempted to start believing it.
Not so fast, bucko.
The remainder of his investigation and conclusions are here:
http://techno-fandom.org/~hobbit/cars/maint100k/
Starting from the 'Brake Fluid' section.
Interesting read. I've owned a Gen 2 Prius and bled the brakes on it, in addition to replacing the rear shoes. I haven't done a detailed comparison of how the braking systems differ, though the procedure/precautions on the Prius are less conventional than the Leaf. Also, perhaps Toyota is using superior materials, extending the life of the fluid?

I will say that I was surprised at how dirty and dark the original brake fluid was on my '17 Leaf after less than two years and a modest 15k miles. It was dirtier than I would have expected from a conventional car without regen, especially because I try to maximize regen when practical. But, my experience is just one data point. I think the Nissan maintenance schedule is a little out of whack with reality, though given what I saw this time, I will probably replace the brake fluid in another two years. By far the greatest benefit to fluid replacement for me was getting a firm brake pedal with a more progressive transition from regen to friction braking. It feels better than when new, though it could just be confirmation bias ;)
 
Oilpan4 said:
Dot 5 silicone based brake fluid is more than likely still fine after 5 years.
That's probably true, but DOT 5 is not recommended for ABS-equipped cars:
https://onestopauto.com/Can-DOT-5-Brake-Fluid-Be-Used-Instead-of-DOT-3-or4.html
 
Yeah I know that's why I put it in my toys that don't have anti lock brakes.
It's way thicker than organic brake fluid and won't flow through the anti lock solenoids at the correct rate to do the anti locking thing.
I'm still changing brake fluid every few years in the on road vehicles.
 
I'm at my 2-year anniversary of purchase. Last year, I changed the cabin filter and took the car in for its 1-year visit, with the old filter and new box sitting on the floor, so that they wouldn't ask to replace it for "only $50." The "battery test" was free, but I think there was a nominal charge ($35?) for "shop supplies" or something... no biggie, I eat their donuts & coffee while I use their DCFC sometimes.

This year, I could do the same thing, but also do a brake fluid change. The big bottle of Valvoline DOT3/4 is $7.50, and I need some for my motorcycle anyway. But I was wondering: is there an official procedure which needs to be followed? (I usually use a vacuum pump to suck-out fluid, one wheel at a time, starting with the wheels closest to the MC). The Maintenance Guide just says "Replace brake fluid", but the Owner's Manual doesn't give a procedure. Also, do I need to keep some documentation, other than the brake fluid receipt?

This is my first car under warranty, so I've never had to care about this stuff before.
 
LeafTaxi said:
I'm at my 2-year anniversary of purchase. Last year, I changed the cabin filter and took the car in for its 1-year visit, with the old filter and new box sitting on the floor, so that they wouldn't ask to replace it for "only $50." The "battery test" was free, but I think there was a nominal charge ($35?) for "shop supplies" or something... no biggie, I eat their donuts & coffee while I use their DCFC sometimes.

This year, I could do the same thing, but also do a brake fluid change. The big bottle of Valvoline DOT3/4 is $7.50, and I need some for my motorcycle anyway. But I was wondering: is there an official procedure which needs to be followed? (I usually use a vacuum pump to suck-out fluid, one wheel at a time, starting with the wheels closest to the MC). The Maintenance Guide just says "Replace brake fluid", but the Owner's Manual doesn't give a procedure. Also, do I need to keep some documentation, other than the brake fluid receipt?

This is my first car under warranty, so I've never had to care about this stuff before.

Here's the page from the service manual. Note: Turn the power ON without touching the brake pedal (i.e., 2 presses)
SOBgUnr.png
 
Interesting that the shop manual doesn't want techs to use a vacuum pump. If I'm alone, I typically pre-pump the pedal to remove residual vacuum from the booster, but then use a vacuum pump when I crack open the bleeder valve. Using no vacuum works fine, but is easiest with an assistant, which would add labor cost for the dealer.
 
LeftieBiker said:
That looks like SOP to me.

There's a bit more to it when viewed in the context of *replacing* the brake fluid instead of just bleeding air. There are specific steps listed under "draining" the brake fluid that I suspect pertain to making sure the fluid in the ABS gets replaced. Some cars specifically require connection to diagnostic equipment to flush the ABS so Nissan may have actually thrown us a bone here.

My thoughts in full, as well as the larger section of the manual in this thread: http://mynissanleaf.com/viewtopic.php?f=30&t=20866
 
That "procedure" page appears to have the wheel order wrong for bleeding the brakes.. The rears are done first, (right, then left). and then the fronts (right then left).. Strange...

Also, replacing fluid uses alot of fluid because you are changing the entire system. it is not just a few pumps for each wheel... You keep on bleeding until the color of the fluid turns clear (new fluid)..
 
Nubo said:
LeftieBiker said:
That looks like SOP to me.

There's a bit more to it when viewed in the context of *replacing* the brake fluid instead of just bleeding air. There are specific steps listed under "draining" the brake fluid that I suspect pertain to making sure the fluid in the ABS gets replaced. Some cars specifically require connection to diagnostic equipment to flush the ABS so Nissan may have actually thrown us a bone here.

My thoughts in full, as well as the larger section of the manual in this thread: http://mynissanleaf.com/viewtopic.php?f=30&t=20866
Why would the drain procedure be better for brake fluid replacement? My thought was that having the brake system energized would cause the pump to move fresh fluid through the ABS module without introducing air, though I don't have confirmation that it's so. I used the bleed procedure until I could see the fresh fluid — the old stuff (at 2 yrs) was surprisingly dark.
 
powersurge said:
That "procedure" page appears to have the wheel order wrong for bleeding the brakes.. The rears are done first, (right, then left). and then the fronts (right then left).. Strange...

Also, replacing fluid uses alot of fluid because you are changing the entire system. it is not just a few pumps for each wheel... You keep on bleeding until the color of the fluid turns clear (new fluid)..

I've bled the brakes on about a half-dozen ABS-equipped cars (various makes) that have a "non-intuitive" order. The results have been good. Barring some obvious mistake in the factory service manual, I'm sticking to the prescribed order.
 
Nubo said:
There's a bit more to it when viewed in the context of *replacing* the brake fluid instead of just bleeding air. There are specific steps listed under "draining" the brake fluid that I suspect pertain to making sure the fluid in the ABS gets replaced. Some cars specifically require connection to diagnostic equipment to flush the ABS so Nissan may have actually thrown us a bone here.

My thoughts in full, as well as the larger section of the manual in this thread: http://mynissanleaf.com/viewtopic.php?f=30&t=20866
...which says
the service manual doesn't explicitly give a "flush" procedure. There's a "drain", a "refill" and a "bleed" procedure.

I am personally satisfied that changing fluid in the reservoir plus in calipers and the connecting lines between them will eventually mix with fluid in the ABS, because this is a fluid, and it moves... but that's my own decision (I am frequently wrong). Draining the master cylinder dry sets you up for a lot of extra work, and I suspect that dealers would not take the time.

My primary concern is that I don't say something to the dealer that lets them twist my arm with a "well, if that's what you did, then you need to let us do it right, or else your warranty is void" argument. So if the Maintenance Guide says "Flush", but there is no maintenance procedure for Flush, what should I tell the dealer that I did?
 
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