how to tell quality of brake fluid - need for change

[bob3dsf]

Hey all, haven't found any threads touching on this aspect, pretty much have only seen about time intervals. So is there a way to tell if the fluid needs changing based on appearance? Mine looks clear/golden. Most people have described their fluid as looking dark and obviously dirty in some way. I've had my Runner a little over a year and unsure when the last time brake service was done before I bought it.

I guess I'm answering my own question if I either 1. just do a flush and start from square 1, or 2. give it another year and do it then to keep with the typical interval recommendation (and assume some service was done recent to my purchase by the dealer) and still start at square 1 then. I guess I'm just wondering if fluid due for a change will usually appear dark as described by others. Thanks.

 

[Skidmarcx]

If its still gold in color and you don't experience any brake fade you're probably fine... Usually obvious when it's time to flush and recommended every three years... However it is cheap to do if it eases your mind

 

[mikebontoft]

Brake fluid is hygroscopic, which means it absorbs water. This is why you really shouldn't let an unsealed container of the stuff sit around. Since water is compressible and brake fluid is not, you can see where the problem is with this- Color is not a reliable factor.

Why does it turn into a dark, murky mess? That comes from the little tiny rubber particles that come off from the seal around the caliper piston and the flexible brake hoses. It eventually gets dense enough with rubber to appear pitch black. Oh and the best part? rubber is compressible as well.

I should also mention that different brake fluids have different boiling points as well. When water is absorbed into the system, it lowers the boiling point. This is where you can potentially experience brake fade with a spongy pedal. Not fun if you're towing your boat down the canyon!

 

[fourwd1]

The color of the fluid in the MC reservoir is in no way a good indicator of what is in the system, since the fluid does not circulate.
The fluid in the calipers and wheel cylinders could be brown goo and you wouldn't know it unless you bled them.

 

[Skidmarcx]

Actually water isn't compressible... It's that it evaporates at roughly half the temperature of brake fluid... Introducing brake fade

 

[Border4Runner]

Brake fluid very rarely goes bad...unless overheated/superheated. Will smell really bad. I drove a Cherokee for 13 years, never changed the fluid and never had any brake issues other than pad replacement.

 

[christo]

It is not essential to change the brake fluid after 3 years or specific period of time if brake is working fine so no need to worry and brake fluid should to change when it gives a smell due to heating. I never heard about to change the brake fluid.

 

[fourwd1]

It is not essential to change the brake fluid after 3 years or specific period of time if brake is working fine so no need to worry and brake fluid should to change when it gives a smell due to heating. I never heard about to change the brake fluid.

Brake fluid very rarely goes bad...unless overheated/superheated. Will smell really bad. I drove a Cherokee for 13 years, never changed the fluid and never had any brake issues other than pad replacement.

Wow, totally have to disagree with that. As was pointed out above, brake fluid absorbs water. Not only does that make it less effective, but it leads to the frozen calipers Toyota's are famous for.

Any automotive fluid wears out and needs to be replaced periodically; brake fluid, trans fluid, coolant, engine oil ...

 

[Border4Runner]

Well, fourwd1 I agree with you that all automtive fluids wear out, but brake fluid has a boiling point of about 300 deg. And, although brake fluid is hygroscopic it would only absorb water if left open to the elements. Most brake systems are sealed. As to toyota's famous caliper issues...this is a seized caliper not frozen. This is due to foriegn material getting past the seal allowing the piston to get seized in the bore.