I've had my C-5 for 21 years, and I've always changed the brake fluid every other year....the best that I can. What i mean is, the C-5s master cylinder has two "sumps" that retain the fluid. The rearmost sump can be pretty well drained, using a turkey baster. However, there's a "divider", for lack of a better term, that pretty much splits the reservoir into two chambers. There's a very small gap under this divider that allows fluid to fill the front chamber.

Here's the problem.....when wanting to empty the reservoir, to fill it with fresh fluid, there's no way to draw fluid out of the front sump. The divider prevents the turkey baster from getting in there, and it's too low to get anything like small tubing under it. As crazy as it sounds, I tried jacking the front end of the car, hoping the slant would get the fluid to run rearward, but that didn't work, either.

As a last resort, I've used my Motive bleeder to pressurize the reservoir, and as carefully as possible, bled the sump down really low, but I'm afraid to get air in the system, so there's always a little residual fluid left, so I don't get a 100% flush. What's everybody else doing, to get around this?

 

Why do you put new brake fluid in every 2 years, just curious. Thanks

 

Due to not wanting to mess with it, I sucked out the reservoir out and refilled with fresh fluid. I will do it every year until it becomes clear.

 

I think it is a reasonable practice to use a rubber bulb syringe to change brake fluid in the master cylinder at every oil change.

Better is to install speed bleeders and do a full flush. For street cars only, every 30,000 miles. For track cars with high temperature fluid in the system at least every two years.

 

Because brake fluid "captures" moisture, which degrades it. This degradation causes the fluid's boiling point to lower, as well as allowing the fluid to become corrosive. Both of those conditions, over time, will damage the braking system.

With respect to SpeedBleeders, I don't care for them. While in theory, they're a great idea, in practice, they don't work all that well, over time. The reason is that for them to work properly, the thread sealant that's used on them has to provide a 100%, air tight seal with the caliper. They will............for the first couple of times that you use them. But over time, the sealant begins to "conform" better to the threads of the caliper, and no longer seals tightly. This allows air to be drawn past the threads, and back into the caliper, defeating their purpose.

 

Old brake fluid leads to corrosion within the system. I had an older Triumph in for service a few years ago, and when I picked it up the service manager strenuously suggested a brake fluid change. I declined, thinking it typical up sell. Master cylinder froze on the way home. fun
Draining and refilling the master as part of a fluid change is a great practice. Significantly shortens the time needed to get clean fluid at the bleed screws — but bleeding until clear (preferably while cycling the ABS) is necessary.
The baster being too large to fit, how about a syringe with tubing? Have not checked mine, but will if it gets above 50F out there.

 

I did the same as you, I used my Brake motive to pressurize, but also did all four wheel bleeding, I went through a lot of fluid and everything cleaned out clear except what was in the EBCM, I don't have a Tech 2 and couldn't get that out.

 

Me too. That's why I'm inquiring about how to drain the outermost "sump" in the m/c. If you don't,and try to push that remaining fluid through the system, down to where you can barely see it by looking through the side of the m/c, you still wind up diluting the residual, when you pour in more fluid. As you mention, yes, you can refill/flush a couple of times, with fresh fluid, but you can't get a 100% fresh refill by having to do it this way......

 

you have the motive bleeder, just bleed new fluid through the bleeders starting furthest away from the master and be done with it. That is if the bleeders loosen without causing problems. Shouldn't take more than a couple hours.

 

OK, I know this one will bring a lot of negative comments. I've owned my C5 almost 20 years. Being a 2000 MY, it is 23 years old now. So is the brake fluid. My EBCM has NEVER given any trouble. My brakes work fine. Car has 130,000+ miles on it. Before all the hate mail comes, my '03 Buick LeSabre had 400,000 miles on its original brake fluid. My 1995 Grand Cherokee had 360,000 miles on its brake fluid. I've never had any brake related issues on any of these cars in nearly 1 million miles, except pads and rotors going bad. OK, let the hate begin!!

 

that's apparently fine & all for doing nothing more than putting around town... until you actually use the brakes hard a couple times.

 

I've made over 50 runs at the dragstrip, slowing from around 130mph to 35mph on most runs, some made without shutting off the engine. Roadracing has never appealed to me, running around in circles while an incompetent driver crashes into my beautiful car. I don't have a built LS7 in my C5 to "put around town."

 

Seeing you have the bleeder, it is pretty easy to take the master off, then the reservoir. Clean with aerosol brake clean and assemble. Or just buy another master with reservoir, they are in-expensive.
The Motive bleeder is ok. Have to be careful there is no bubbles in the fluid from moving/jarring around. If there is any left in the bleeder, it is still exposed to air. A diaphragm style bleeder is better but way more expensive. For the time frame you are doing this procedure it will be fine. Owners manuals of most manufacturers say change the brake fluid every 2 or 3 years. This was in the past decades. Have not seen any late manuals to check. I am sure some do not say it at all.

 

Let a vehicle sit with old fluid for a couple of years longer than I should have. I noticed the brakes just didn't seem to be as effective as they once were; not totally useless but just not very inspiring. I decided to maybe change pads. I found the real culprit when I removed the calipers and tried to depress the pistons back into the body of the calipers. All of them had a frozen piston or two (rusted). All of the stopping power was from the few free pistons. Not the best situation. Yes, fluid does attract water vapor. That is one reason to not use old fluid when flushing. The collected water vapor had attacked the metal and rust/welded the pistons. New rotors, new calipers and a couple of brake lines to replace the boogered up ends on the old from trying to unscrew the frozen fittings. I knew better, I have been changing fluid regularly in my other vehicles and the two track cars especially for many years but this vehicle bit me in the butt from my neglect. Never again. For my C5 I just suck up the old fluid, pour in fresh, clamp on the Motive Bleeder cap, pressurize to 10psi, bleed RR,LF,LR,RF (of course, repenish the fluid a couple of times during bleeding). Have always had good braking in heated sessions at the race track.

 

Corvette owners put their cars to a very wide variety of uses, some are car car show enthusiasts, others simply drive on the street, others participate in organized drag racing and yet another group are road course enthusiasts. These are VERY different uses and stress the brake system over a range of -- not much on the street -- to road course use which can result in heating of the rotors and pads to the point of insipient or actual brake failure caused by boiling of the brake fluid.

An example would be Laguna Seca where I have spent many days. 11 turns, 2.3 miles around. In a 20 or 25 minute session I would accelerate out of a turn to 80 to 110 then brake for the next turn. 11 turns, 10 laps, 20 minutes = 220 acceleration and hard braking events in one session. One braking event every six to 10 seconds.

AFTER a cool down lap and parking in the paddock at Laguna Seca I once measured front rotor temperature on my car at 550 degrees F.

For the above reasons I consider the brake fluid in my car to be wet after no more than two years and flush the system. I use ATE Typ 200 shown below. But you can make your own choice.

 

I use the Castrol React SRF. Using temperature paint the front rotors were around 1000 degrees. Calipers around 800 degrees. Rear rotors around 800 degrees, calipers around 500 degrees. Consistent at WG and LR. Wilwood set up with cooling ducts. When I bought the Castrol it was $75 a ltr. It has come down now.

 

I just skimmed this thread, and with all due respect most of you are as batshit crazy as my wife. While it wont hurt anything to have "extremely fresh" brake fluid, you don't drive around with the lid off the reservoir. If you do you're asking for a severe dose of reality.

For those reporting rusted pistons I have to ask if you're the original owner of the car. If your answer is "no", you quite simply don't know the history of the vehicle. Some previous owner / dipshit / dipshit mechanic might have left it parked with the brake fluid res cap sitting off for weeks, months, or years and caused serious water absortion. You simply don't know...

I've run vehicles from 250k - 500k miles with the original brake fluid. Never had a single hydraulic problem that wasn't caused by a brake booster or master cylinder seal failure EDIT: or a cut brake line.

 

Although I cannot find my pictures of the brake master, here is the clutch master apart. This is from the '04 I bought with 5436 miles in Nov. '19. This is some of the dirt, rest was in the master. This is a known issue. Some cars do better than others. Climate probably makes a difference. I have seen it go both ways. Looking at the pictures of for sale cars on the forum, I have seen more of them with dark brake master reservoirs. The cap is vented to atmosphere, just like all the running gear.

 

I was under the impression that the C5 calipers have stainless sleeves in the bores. Is this incorrect?

 

I tend to agree. Another thing most people say is to change the fuel filter. Other than possibly reducing the likelihood of being stranded due to a fueling issue, I ask why? It's a proven fact that, as virtually any filter traps impurities, it also filters better than new. Until it restricts flow of fuel, oil, transmission fluid, air, etc. That said, in my previous post I made note of the fact that 3 of my vehicles have traveled close to 1 million miles, all without a brake fluid change. Add no fuel filter changes to that list! Oil and transmission fluid/filter changes are obviously imperative. Air filter changes must also be made occasionally, in most cases. But I truly believe 10s of millions of $$$ have been wasted by changing things that really will not cause any damage if left alone. I'm not saying people shouldn't do it. Jim993 obviously needs to change his brake fluid more often than I do. However, I think the statement "putting around town" is an exaggeration, and that's not what's happening, at least on my car. Certainly I don't torture my brakes to the same degree Jim993 does. But unless youve ever gone 130mph in a 1/4 mile, and seen the end of the track approaching rapidly in another 1000 feet, and climb on the brakes hard, you don't really realize how hot the brakes can get, quickly, as you're running out of track!! Not as hot as Jim993's brakes get, but they get a Helluva lot hotter than "putting around town!" What I am also saying is I'm not pumping garbage at the gas station during a fill up. I have occasionally gotten fuel with some water in it, a situation which a brand new filter wouldn't help, and dry gas will. When it rains, and I know my car needs a good wash anyway, I occasionally take the car out and "exercise" the ABS system. This has always worked for me, YMMV....