Can (old) brake fluid freeze?

[Dackelone]

Ok, so last week I go to look at an (13+ years) older used BMW... the owner and I go for a spin... as he makes the first turn and go to put the brakes on... the car has no brakes(!) and he pulls the E-brake in order to advert a crash. I thought at first the guy just can't drive! lol

Anyways.. he calls his Mechanic friend... and his friend tells him its either water in the brake fluid(bc the fluid is really old!) or... a bad master cylinder. btw... the brake pedal was ROCK hard and the outside temps were in the single digits('F) and the car had not been driven in two days(also parked outside in the super cold weather).

To my thinking it might be (more likely) water in the brake booster - causing no assist. We have had highs of only -8' C in the day and close to -25'C this last week or so - over here.


So... this guy's story sounded a bit BS-like to me! I got to thinking... can brake fluid freeze? I did notice the brake booster on this car was new. The master cylinder looked old though.


Any thoughts>???

[Focusedintntions]

Well brake fluid, specially the older stuff, will absorb water moisture out of the air. Thats what will cause rust in brake lines eventually. So if enough water has been absorbed, then yes, it could freeze in the lines. I'd say it's improbable, but possible if the braking system has been neglected enough.

[GaryS]

Is it a race brake fluid? Afaik all name brand street brake fluids are good at resisting moisture. But some race fluids that are intended to be changed frequently absorb moisture very quickly in exchange for a higher dry boiling point.

[Dackelone]

Originally Posted by GaryS

Is it a race brake fluid? Afaik all name brand street brake fluids are good at resisting moisture. But some race fluids that are intended to be changed frequently absorb moisture very quickly in exchange for a higher dry boiling point.

No. Just plain old street stuff. Probably DOT3 or DOT4.


I ened up passing on that used car bc some of the other things did not add up. Current owner only has the car for one month. Now his friend (with a used car lot) is selling it for him... as a favor. Something was fishy with that car. I found another good clean e39 though. With a much better service history.

It is just that I have never heard of brake fluid freezing. I still think it was a BS story. We all know how used car salesman can "bend" the truth. lol

[RedTRex]

Here is a simple link to explain, but more or less, neglect is very very bad.....

http://www.aa1car.com/library/bfluid.htm