Brake Fluid with low freezing points?

*DizzyEdge* · 01-02-2009, 09:30 PM

I've noticed once in a while, on a very cold winter morning, that the first time I depress my brakes things are fine, but the second time it's like they're frozen solid (which sucks when you're headed for a stop sign). They are useable, but you practically have to stand on them like your forcing the piston through cold molasses. This only happens the first time, and when I say cold winter morning I mean the car has been sitting outside in -15 to -30 F weather. after sliding through one stop sign I now make sure I do the pump of doom right after I pull out from the curb. I also notice the same issue has been mentioned years back in the Canada forum.

I'm wondering if the brake fluid is actually approaching it's freezing temp? I checked some random DOT 3 specs for freezing point (most don't seem to list it but I found a few), and I came up with -40 to -50 F.. if you assume -40. and you assume the fluid is a few years old and has absorbed some water, I'm wondering if you might end up with a frozen solid temp only 10 to 15 F less than the outside temps? Either way I'm replacing the fluid in the next week, but I'm curious if anyone else has experienced this?

96blkonblkse · 01-02-2009, 11:12 PM

Are you sure your brakes arent getting wet? I have this problem every time it rains. With my BBK, i had to remove the back splash shield to accomdate a thicker larger rotor. Whenever its wet out, my brakes flat out suck *** for the first application. I am designing a new shield to put on, because its like driving around with no brakes at times.

If it was a problem with the brake fluid, logicically, it would happen all the time its cold. Brake fluid aborbs moisture though, so if your fluid is old, its a good idea to flush it out!

Perhaps its just that cold, the moisture is freezing on your rotors when you drive and your getting like an instant layer of pre-rust?

*DizzyEdge* · 01-02-2009, 11:16 PM

Quote:

Originally Posted by 96blkonblkse

Are you sure your brakes arent getting wet? I have this problem every time it rains. With my BBK, i had to remove the back splash shield to accomdate a thicker larger rotor. Whenever its wet out, my brakes flat out suck *** for the first application. I am designing a new shield to put on, because its like driving around with no brakes at times.

If it was a problem with the brake fluid, logicically, it would happen all the time its cold. Brake fluid aborbs moisture though, so if your fluid is old, its a good idea to flush it out!

Perhaps its just that cold, the moisture is freezing on your rotors when you drive and your getting like an instant layer of pre-rust?

It's really hard to say.. .it only happens when the car has been sitting 8+ hours at -15/-20F or colder, and when I get in the car, the first time I press down the brake it's fine, it's once I lift my foot off the brake and drive off the NEXT time i have to press insanely hard to get it to brake, it's not rock solid, but there's an incredible amount of resistance to basically get the piston through the master cylinder.. but once I do finally succeed, it's fine for the rest of the trip, and it's never ever happened during warmer temps.. and I seem to recall now that my 3rd gen maxima did that sometimes as well. I guess I'll just check and see if there's improvement after the lines are all bled. I just figure if the specs are that unopened fluid would freeze solid at 20 degrees colder weather, that it might be terribly thick at -20 F or so, but I suppose that doesn't explain why it only had issues the first 'squeeze'

***talkinghorse*** · 01-03-2009, 06:42 AM

While you could have moisture in the fluid, the pattern of your problem does not lend itself to that...if the fluid was "frozen" you'd continue to have the problem until it was warmed....and given the brakes work well the first time you depress the pedal kind of tells me something else is going on. No way they're wet at those temps.

Just guessing, but since the brakes work fine the first time you depress the pedal, perhaps it's a problem with the vacuum assist not regenerating quickly enough at those cold temps??? I'm thinking of the brake pedal sensation you would get by depressing the brakes with the engine off...it will work fine the first time you depress the pedal, but after that, the effort needed to push the brakes down increases tremendously. Just a thought.

*DizzyEdge* · 01-03-2009, 07:26 AM

Correct me if I'm wrong, but I'm thinking one way to test would be to get it to 'jam up' like that, but while parked, and just wait and see if it comes back to life eventually without massive foot pressure?

***talkinghorse*** · 01-03-2009, 07:31 AM

Quote:

Originally Posted by DizzyEdge

Correct me if I'm wrong, but I'm thinking one way to test would be to get it to 'jam up' like that, but while parked, and just wait and see if it comes back to life eventually without massive foot pressure?

It's definitely worth a try...press the pedal a few times, while parked & running, after you first start the engine and see if you can duplicate your problem...if you can duplicate it, let the car run for a bit and see if it regenerates. ed

*johnnyd2k2* · 01-04-2009, 07:02 AM

You're not the only one this happened to me twice this week it really freaked me out I was pulling out of my driveway and almost T-boned a car I'm gonna flush all the fluid soon hopefully it will help. I just pump the brakes a bunch of times before I put it in drive now to keep it from happening again.

*DizzyEdge* · 01-04-2009, 06:34 PM

Quote:

Originally Posted by johnnyd2k2

You're not the only one this happened to me twice this week it really freaked me out I was pulling out of my driveway and almost T-boned a car I'm gonna flush all the fluid soon hopefully it will help. I just pump the brakes a bunch of times before I put it in drive now to keep it from happening again.

And there's 3 or 4 similar comments on the Canada forum from a few years ago, so I guess it's not really an anomaly. Any idea what the temps were when this happened to you? or what they were overnight if it happened in the morning?

**Matt93SE** · 01-07-2009, 02:59 PM

Fiddling with the brakes in the driveway before you go anywhere is a good way to see if it's the fluid.

BUT.. considering that you're seeing the problems after the first brake application, I wonder if it isn't something to do with the rotors and pads themselves.

what kind of brake pads do you have on the car?

Is it possible that the first application warms up the rotors just enough to cause water to condense on them and then cause a wet rotor no-brake issue?

Also try the mechanical parking brake and see what happens. If the car still slows as usual with the parking brake, then I would agree that it's a hydraulic problem. But if you can't stop with the parking brake at all either, then it's possibly a glazing issue on the rotors..

Do any of you guys experiencing this have drilled/slotted rotors?

*durckelg* · 01-22-2009, 09:22 AM

Was a solution found?

I am having the same problem. I was planning on changing the fluid this weekend. I hope this will help, however I am running Auto Zone Duralast pads and rotors, so that may be the problem. This combination initially had great bite.

I doubt the problem is condensation on the rotors. For that to happen the rotor would have to be cooler than the air, correct me if I am wrong?

BluFlame · 01-23-2009, 06:51 PM

it's the booster, just pump it once or twice before moving.

*johnnyd2k2* · 01-25-2009, 07:50 AM

I had my brakes looked at and found that the problem was the caliper pins were rusted and had no greese left on them and it was causing it to stick, had them cleaned and relubed and now they're fine.

*durckelg* · 01-26-2009, 09:13 AM

Thanks johnnyd2k2

I changed the fluid. The brakes seem to work a little better now. I think the majority of the lack in performance was due to the rotor and pads being ~5 degrees F. I did few runs from 60-10. The abs was easier to kick in each time.

I did check the pins while I was at it. They were still very greasy.