Flushing Brakes

[carmen142]

Hi All

I have a 41 P12 4 door that I want to flush out the brakes. I have never done this and really have no idea on how. I have blead the system for air before but never flushed it. Is there a special oil that I use to flush out the system? Do I let it sit over night? Any help.

Thanks

Carmen

[Young Ed]

I would just bleed all the wheels liberally so fresh fluid is in the system.

[TodFitch]

A fellow I know who was into racing flushed his brakes after every racing weekend. Apparently the racing crowd knows where to buy brake fluid with some dye added. So he had two pressure bleeders each with its own color of brake fluid and he alternated which bleeder he used. He said he flushed them until the fluid came out the color of the stuff in the bleeder.

For us more everyday types, I think I'd just flush until the fluid comes out looking clean.

On the other hand, I switched to DOT5 when I rebuilt everything and, as I understand it, periodic flushing is not required with that. It has been about 12 years since I did that and I've had no problems and the fluid still looks clean in the master cylinder.

[chopt50wgn]

If the system is contaminated with something other than brake fluid, then you should use some sort of flshing liquid.

If you just want to flush the old fluid out, you open the bleeder till the MC gets low ,but not empty. Then continue flushing and filling the MC till the fluid is the new stuff.

I have a pnuematic flusher that you hook up to an air line, attach the rubber fitting to one bleeder and push down on the handle. The flusher pulls all the old fluid thru the system by opening just one bleeder.

[greg g]

If you look at your brake lines, you will see the pass side rear well is the furthest from the MC. As such the line to that wheel also contains the most fluid. So you start by opening that bleede, and go through the bleeding procedure typically old fluid will be dark and murky while new fluid light and clear. You can put a piece of clear tubing over the bleed nipple and direct it into a container Like a clear 2 liter soda bottle. By putting some clean fluid in the clotainer and directing the tubing into it you can pump the MC without sucking air back into the system when you release the pedal. Using a clear container and clear tubing you can see when the fluid changes.

When it does, move on to the other rear wheel , then the pass front and finish withthe driver's front. that way you can pump out the old while adding the new to keep the MC filled, and see when the fluid chang goes throught the line to the wheel cylinder. If you have an assistant, they can watch for the change and tighten the bleeder.

Also, I have been told that while bleeding the brakes you chould neer allow the pedal to go to the floor. This pushed the MC piston past any wear ridge that may have built up in the MC and the ridge may score the pubber as it passes the ridge. a piece of 2x4 under the pedal will prevent the piston from traveling the full stroke but still allow you to push out the fluid.

[desoto1939]

Instead of using the old method of pumpiong the brake pedal you could get the new siphon system for around $25 and then bleed the lines and this is a one person operation.

Keep you eye on the Master cylinder to keep is filled with brake fluid.

If you are converting from DOT3 to DOT 5 which is silicone then you will need to flush the entire system with denatured alochol and replace the 3 brake hoses, rebuild the MC with new fresh rubber and also each wheel cyclinder with new fresh rubber. The system has to and I will state again ca nnot have any of the old brake fluid left in the lines.

Put the system back together then use the siphon bleeder and start with the right rear, left rear, front right then front left to bleed and you should be set.

Rich Hartung