Flush your brake fluid!

How old is your Roadster, Frequency Dip?

Without looking it up, I think I saw in my owner's manual they recommend replacing brake fluid every 2 yrs regardless of miles because it absorbs moisture and forms the corrosive gel that you saw. I think better quality brake fluid might prevent that.

Have you notified Tesla? Maybe they simply haven't had enough Teslas that are 2 years old to notice the problem.

I've had 10+ year old vehicles that never had the brake fluid changed and I've never seen what you describe. Something seems odd there.

Ranger Larry said that bleeding the breaks is done once every two years. (If my memory serves me correctly) I may ask if we(he) can do mine today.

Brake fluid is hydroscopic and should be changed/flushed each year. I bleed out the fluid on my buddies 1.0 about a month ago. Luckily things were still liquid, but very dark. Make sure to use DOT4 only. The local dealer here only charges a little over $100 to bleed the brakes which isn't any more than any other car would cost.

Since the brakes are a sealed system where is the moisture coming from? Yearly brake flushes? That sounds crazy.

Moisture can come through the seals on the calipers, master cylinder through the breather on the resovoir.

Mine is going in for its second annual service this coming Monday (Menlo Park store). I will raise this question and see what happens...

Fluid on my BMW gets changed every year by BMW at their cost while under warrenty.

Lloyd said:

Moisture can come through the seals on the calipers, master cylinder through the breather on the resovoir.

Click to expand...

If moisture can come through the caliper seals wouldn't brake fluid leak out of them? Are they building master cylinders differently now? I don't remember seeing a breather on any master cylinder, they always had a sealed cover with no vent. I've just never encountered the brake fluid dynamics that some of you are describing.

it's a piston with with a wiper seal. Each time it goes each way a little moisture has the opportunity to be absorbed by the fluid. This is especially true in rain and moist environments. It is not as completely sealed as you might think.

There are many things to consider.

For one, when the atmospheric pressure (temperature) changes, the difference has to come from somewhere, and usually some part of the brake system pulls in "air" - but note that air always has some amount of water vapor. So, it's not pulling in water, per se, but pulling in air that eventually condenses into water.

Four wheel drive vehicles have to design around this because often the systems are under water, and the pressure changes will suck in water through every available avenue. Such systems have venting at a high point in the vehicle so that it's easier for air to come in up high than for water to come in down low. But the point is that if they could just make it "perfectly" sealed then they wouldn't bother with all of this venting, which just provides evidence that perfect seals are not really feasible in consumer or even most military vehicles. Note, the venting I am describing is not for brake lines, but it should illustrate the difficulty in making perfect seals on any system that is exposed to environmental changes.

For another thing, there are many grades of brake fluid, up to DOT 5 and DOT 6, I recall. Some of these are better than the DOT 4 that is in the Roadster, but they're also more expensive and more trouble to deal with. In other words, there is nothing substandard about the Tesla Roadster brakes, it's on par with the bulk of vehicles out there.

But the fluid issues reported and the change intervals are not standard from my experience. In fact I've had a number of off road vehicles that regularly went in deep water and mud and I never saw excessive water or gelling in the brake fluid and never did yearly brake flushes. In most cases unless I had to change system components they never got a full flush and never had any issues, and this was with regular DOT3 fluid. I'm just mystified by the fluid change intervals some of you seem to think are standard. If some mechanic suggested to me a yearly brake fluid flush I'd think he was trying to rip me off and I'd never go back there again, but I've never heard of such a thing before. Maybe the DOT 4 and up fluids are more sensitive to moisture?

FYI Ranger says, "The fluid (brake) is bled every two years." and that if you are seeing fluid gelling you have some sort of contamination in the fluid. (And should call Tesla Service)

All brake fluid absorbs moisture, that is their intention. It prevents water from accumulating in the system and creating steam when hot and affecting braking ability, or corrosion internal to the calipers or master cylinder. High performance cars are usually more sensitive to this due to the higher temperatures, generated. Street vehicles with normal operation are not as critical. I bleed my wife's car every couple of years. Airplanes are bled annually. I took my M6 on the track with a professional race team. They insisted on bleeding the brakes after the racing run and returning the car to the street!

Heat cycling is what causes most of the moister to develop and allow contaminants into the brake fluid along with seals, cap, vent etc. As some have mentioned, track use is the most critical because brake fluid has an incredibly high boiling point. Water of course, does not. Little particles of water can boil and tadda, they can compress! Ever gotten brake fade? That's a part (not all) of why brake fade happens.

These are $100k cars, spending $100 or so to care for part of a system that has such an impact on safety seems non-debatable to me.