...about cars in general. I grew up in Hawaii as an army brat and pretty much walked everywhere, but at least I have character! That's what I was told I'd get for walking when I asked for help getting a car.

Anyway, at 31 I was finally able to buy a Corvette as I've always wanted to. It's an 81 and in pretty sweet condition.

However, I now notice my brake light coming on when I brake. Usually when I pump the brakes, it will go off. I'm assuming my brake fluid is low so I opened it up and see two chambers. One is filled almost full with clear brake fluid and the other is lower but the fluid is a darker cloudy color.

Is this the same DOT 3 fluid for both chambers and should they both be full? Also, why does one look different?

Sorry if this is a noob question, but hey, I won't ask the same question twice. :blueangel:

 

Hi there. :seeya Another 81' owner is always a good thing. I like your interest in learning to do some of this stuff yourself. :cool: It's never too late to learn, and there's never a stupid question. Nobody here will rough you up for asking a question no matter how simple or complex it is. It is DOT3 brake fluid in both sides. One side is for the front brakes, one if for the rear brakes. I think that a fluid change may be in order for your car, however that's not the end of the work possibly needed. You need to look at your calipers to see if they have fluid leaking out of them. Look from under the car at the bottom inside of each wheel to see if there is fluid running down. I find it works out pretty well to park the car in a clean place, then go under the car and clean off the bottom of the wheels real well, then pump the brakes a few times and leave it set for a few days. Come back and see if any fluid has ran down the wheel from the caliper on the top. The brake calipers are known for rusting in the bores and causing leaks. This is easily fixable with stainless steel lined calipers. For now put some DOT3 in that low side of your master cylinder, that should help you brake problem for now.


-Justin

 

The brake light will come on if the pressure is doing something funky.

The murky color in the fluid might indicate that there is a problem with that set of brakes front or rear somewhere. Or it could mean that the front brakes had been redone and new fluid added at some point but not the rear. Or vise versa.

You might want to bleed the front or rear with the darker fluid and see how that goes. It should be the same DOT fluid for both chambers and yes, they should both be full. They are seperate systems for front and rear and thats why they will look different. If everything is working good and not leaking fluid they should look the same.

As for what causes the fluid to get murky and dark im not sure. Could be rust in the lines somewhere? I would start with a good brake bleed, and check the lines/caliper for leaks. Brakes are important. If your not sure on this one or if its not apparent what the problem is, there is no shame in asking a good mechanic to check it out. Could save you.

BTW- The rear calipers have 2 bleeder screws.

 

:iagree: That cloudiness is likely a combination of water and corrosion. Brake fluid is notorious for absorbing water, and once it does, it starts rotting your brakes lines from the inside out. Change the fluid, and change it again every once in while, so you don't end up with brake lines with holes in 'em. :thumbs:

JB

 

Awesome information, thanks especially for the walk-through on checking that stuff.

 

I added brake fluid and the light still comes on when I use the brakes, but goes off usually if I pump thm or brake twice.

Guess it's on to step B.

 

Most definately bleed the brakes. When my 81' used to get some air in the lines it would do the same thing you describe.

 

I agree that you should bleed the brakes. If you are not sure of the procedure post here. (we don't know your level of mechanical repair knowledge yet.....not trying to imply you know less than you do or anything). :) Speed Bleeders are a nice easy way to bleed your brakes yourself. Just install them in place of the regular bleeders, open the bleeder a quarter or half turn and pump the brakes. Close the bleeder when you're done. Otherwise the good old two man bleeder method works good for me.


-Justin

 

Thanks for offering the help and yes, please explain how.

At the risk of pissing other people, I am a vette owner with little mechanical knowledge. (So far anyway, but I'll learn, by God)

 

I think you might want to look at your calipers first.

The "Brake" light coming on in the dash can be indicative of a pressure differential between the front and rear halves of your system. This can be caused by a leak at one or more calipers in the system.

If you look down below your master cylinider, you'll see that the lines feed into a little manifold-like thing bolted to your frame. The brake lines go in and then they come out and a pair of lines get routed to the frint calipers and a single line travels to the rear of the car and splits to feed the rear calipers. There is also a wire coming out of the unit.

This is called a "Pressure Differential Switch." The way it works is there is a piston inside that is held in a centered position when the fluid pressure in both the front and rear systems is the same. Get a leak in a caliper, either front or rear, and one side of the system has more pressure than the other. This causes the piston inside to move out of the centered position and that closes a circuit that trips the "Brakes" light in the dash.

As for your fluid, I would recommend making your repair to fix the pressure differential and then bleeding all of the old, cloudy fluid out of the system and replacing it with new fluid. There are many ways to do this--pressure bleeder, etc.--but you can bleed your brakes the normal way, topping off the master cylinder with fresh fluid and just keeping at it until the fluid coming out the bleeders is clear.

I'd also recommend upgrading from DOT 3 to something like Castrol GT LMA (Low Moisture Absorption) fluid, which exceeds both DOT 3 and DOT 4 specs. I've heard that the guys wearing the Blue Oval (F**d) make a pretty darn good brake fluid, too.

Good luck with your project.


[Modified by The Dude, 11:06 AM 1/6/2004]

 

grab a basic repair manual for you car at parts store, read it a few time's
and don't sweat askin' for help, people like to help out those that want to learn
and enjoy their cars :thumbs: :flag

 

So I went to bleed the brakes and the front ones seemed fine. That had the clear fluid anyway. For the rear brakes, I couldn't even get fluid out..at all.

So I took it to a mechanic and it turns out my master cylinider itself is bad and I've only had the use of my front brakes. (hey, its hard to tell on a "new to you" type car, right?)

He's putting a new master cylinider on it now. If this works out, I'll move on to having an actual working horn.


[Modified by Scorn, 8:46 PM 1/8/2004]


[Modified by Scorn, 8:47 PM 1/8/2004]

 

when you get it back you tell a difference. 60-70% of braking on front on
most cars

 

Huge difference. Feels a lot better. I did notice my brake light came on for a hard stop once tonight, but it went right back off. I hope the new master cylender did the trick for a while.

 

Sounds like you got the brake problem worked out. No shame in taking it to a mechanic. I will ONLY work on my own brakes. I've had family ask me to work on their's, but I always tell them no. If I die because I screwed up my brakes that's one thing, but I'm not going to be held liable for working on someone else's brakes.

As for your horn, Mid America (and I'm sure other vendors) has the parts to fix it. Mid America's website is http://www.madirect.com

To find some other vendor sites (that support the forum), scroll all the way to the bottom of the forum page and look on the left. You'll see Zip and Corvette Central as well as a few others. They might carry the horn parts too.

 

It took about a day for the brake light to start coming on again, dangit. I noticed it comes on easier with a hard brake, but sometimes stays on after that.