Do brakes need bleeding?

Vincent Keene · **Posted:** Wed Feb 04, 2004 9:53 am

After replacing pads and rotors is it always necessary to bleed the brakes? Does forcing the piston back into the caliper somehow cause air in the system?

I'm trying to learn even more from our vast Tarheel automotive knowledge data base.

Adam Ligon · **Posted:** Wed Feb 04, 2004 10:44 am

Technically no. If the system doesn't leak to begin with, don't you have a chevy so lets assume its not boken for once

, then pushing back in the piston just pushes the fluid back into the resivoir.

I tend to do it as general maitenance at least every yr or when I change pads, as the fluid absorbs water over time, lowering the boiling pt.

Vincent Keene · **Posted:** Wed Feb 04, 2004 10:54 am

Well this isn't my car. It's an '02 Saturn L100 sedan. I changed the pads and rotors for a friend here at work.

The new pads are really thick (compared to mine when new) so I had to compress the piston a long way for them to fit. Now there is a good bit more pedal travel than before.

Obviously there is a problem, I was just wondering if this was common?

Marvin McBride · **Posted:** Wed Feb 04, 2004 9:52 pm

Did you do all 4 corners or just the fronts? I don't know about the Saturn, but in most cars, the rears tend to be more complicated since they have to handle the parking brake duties, and may need to be manually adjusted after the piston is compressed.

FWIW, brake fluid is relatively cheap, and I usually give the system a complete flush any time I change pads.

Brad Mackey · **Posted:** Thu Feb 05, 2004 12:50 am

I agree with Marvin.
Brake Fluid, even the real good stuff, is a relatively cheap PM operation. Most brake systems appear to be air-tight, but fluid still seems to turn cloudy over a few months, which indicates some kind of deterioration or moisture absorbtion.

If it's moisture, then get it the hell out of there! Even if it's not, keeping the brake fluid fresh will prolong the life of all them li'l rubber parts in the system.

If the car's going to the track, it's a no-brainer. You gotta do it.

My .02 worth.

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Graham Jagger · **Joined:** Fri Aug 29, 2003 12:53 am **Posts:** 1718

Yes they do. Over time it degrades. Take a car that hasn't had the fluid bled for about 2 yrs. Bleed off at least 2-4oz at each wheel. Take a look at the stuff and compare it to fresh fluid. Your question will be answered... :wink:

As the others have said. It's part of routine PM and if you've got everything apart replacing pads/rotors then it's the perfect time. You've already done all the hard part.

Get a small MityVac for about $30 and you can do it yourself as long as the bleeder screws are good. Follow the standard procedure of furthest wheel first. Typically LR, RR, RF, LF but some cars differ in the order. Get the big bottle of brake fluid or 2 of the smaller ones. Keep on draining until the fluid looks clean. To speed up the process go to the reservoir first and with a syringe or baster suck out all the old fluid. Fill it with fresh fluid and then start bleeding until you get clean fluid.

Vincent Keene · **Posted:** Thu Feb 05, 2004 10:01 am

Thanks for the info guys. This car won't be on a track, but good brakes are always a must right? I'll go ahead and bleed 'em this weekend and swap out the fluid.

Why don't they just put speed-bleeders on all cars? It makes it so much easier!

Graham Jagger · **Joined:** Fri Aug 29, 2003 12:53 am **Posts:** 1718

Vincent Keene wrote:

Why don't they just put speed-bleeders on all cars? It makes it so much easier!

Because they would be a $150 factory option :roll:

Dave Phillips · **Posted:** Mon Feb 09, 2004 10:58 pm

For flushing your system, the pressure bleeders, like the Motive Pressure Bleeder, work great. They pump more fluid to the resevoir as you drain at the bleed nipple. This prevent you from running the resevoir dry thereby sucking air from the top.

I run Ate Super Blue fluid and flush every three months. The Motive bleeder makes it a one man job and I get a good hard pedal every time.

Todd Breakey · **Posted:** Wed Feb 11, 2004 6:16 pm

Dave - Where did you get your pressure bleeder from and how much was it? I have looked for them but can't seem to find them anywhere.

Dave Phillips · **Posted:** Wed Feb 11, 2004 6:31 pm

Todd,

You can order the Motive bleeder from Motive Products. I believe they are now $47.95. You can learn more at www.motiveproducts.com or call 1877 59-BRAKES.

You will love it. I don't work for them or anything. I'm just a satisfied customer.

Adam Ligon · **Posted:** Wed Feb 11, 2004 6:36 pm

Dave Phillips wrote:

Todd,

You can order the Motive bleeder from Motive Products. I believe they are now $47.95. You can learn more at www.motiveproducts.com or call 1877 59-BRAKES.

You will love it. I don't work for them or anything. I'm just a satisfied customer.

I actually just used one of the motive's and can't say I was very impressed. They are expensive and very wasteful as well as messy. I would go with the type that works with shop air and hooks to the bleeded myself. Harbor Freight, Autozone, and Northern all have this stlye fro around $25.

Dave Phillips · **Posted:** Thu Feb 12, 2004 1:54 am

Adam,

It sounds like the adapter was not properly fitted if it was messy. I assume you are referring to a mess around the brake fluid resevoir.

The one down side is the lack of a swivel on the hose. It can be a pain to screw on the resevoir.

As for hooking up to shop air, who has shop air at the track? I can bleed all four corners very quickly, at the track between sessions once I get the car jacked up and get the bleeder connected.

Adam Ligon · **Posted:** Thu Feb 12, 2004 9:57 am

Dave Phillips wrote:

Adam,

It sounds like the adapter was not properly fitted if it was messy. I assume you are referring to a mess around the brake fluid resevoir.

The one down side is the lack of a swivel on the hose. It can be a pain to screw on the resevoir.

As for hooking up to shop air, who has shop air at the track? I can bleed all four corners very quickly, at the track between sessions once I get the car jacked up and get the bleeder connected.

The mess I am reffering to is not from the resivior connectione but when you are done bleeding the system. There is still fluid in the hose from the bleeder to the resivoir which spills out when you disconnect it. Also you don't run the bleeder dry so now you have the fluid left in it which has been opened and exposed to air which begins the very quick downgrade of that fluid.

And I wasn't thinkng about track bleeding before. Though there are the portable air tanks that alot of people use for tire adjustments.

Dave Phillips · **Posted:** Thu Feb 12, 2004 10:11 am

Adam,

Are the compressed air bleeders a push or pull type system? I am not familiar with them.

As for the fluid left in the hose, I have a solution to that. When you are bleeding the last corner, closest to the MC, you need to tip the bottle so that there is no fluid at the pickup. The fluid in the hose is driven into the resevoir as air is now driving the system.

This is recommeded at the very end to drop the fluid in the resevoir to the max line. Otherwise, your resevoir will be over-filled.

The biggest mess is experienced by Porsche owners who do not clamp off the overflow tube. You can drop a whole can of Ate Super Blue in the driveway or on the garage floor by making this mistake. While you are pumping the bottle trying to figure out why the pressure won't stay up, your fluid is puddling below the front bumper.

Ask me how I know!!!

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