brakes

[lyndon Sharpton]

I need to flush my brake system. should I take most of all the old fluid out of the master cylinder with a vacuum pump? then put in new fliud an then can I just use the gravity method to flush an bleed?

[Wayne K.]

Re: brakes

Lyndon,

If your are not experiencing any problems with your brake system then the method you described should work just fine.

Wayne

[Duke W.]

Re: brakes

Absolutely remove the old fluid from the reservoir!!!

I just siphon it out. When empty carefully inspect the bottom of the reservoirs and remove any sludge or debris. Use tools that are absolutely clean and have NO petroleum product residue. You can swish around fresh fluid and siphon it out as a final check that the reservoirs are clean. If you flush every couple of years the reservoirs will usually be clean, but if you are dealing with a vehicle that has not had regular fluid flushes, which is typical, there is likely a good deal of gunk at the bottom of the reservoirs.

Once the reservoirs are squeaky clean fill with fluid and begin the flush. I'm not a fan or "gravity bleeding" or "vacuum bleeding" by using a vacuum pump at the bleed valves. I prefer to get a helper and have them run the pedal while I work the bleeder valves and check that the m/c reservoirs don't run dry.

Duke

[Randy S.]

Re: brakes

Duke,
Great tips. As a novice i need a few more.
What is the recommended sequence for each caliper, rears first or fronts first. I don't recall if it was longest lines or shortest lines first.
Also on the rear calipers there are 2 each bleeder screws. Bleed both??

Randy

[Duke W.]

Re: brakes

I always start with a left front as this is the shortest path for the old fluid (or air) in the line between the m/c and junction block to be expelled from the system.

On a dual circuit system, the LR is probably the shortest path for the rear circuit on most cars.

To insure proper purging of all the old fluid you need to flush both sides of the rear calipers. While bleeding the rear corners, just swap back and forth between the two.

Flushing through a quart of fluid (starting out with fresh fluid in the reservoir(s)) should purge most systems since most automotive brake systems have a brake fluid capacity of no more than about one pint.

Using clear vinyl tubing will also allow you to observe expelled fluid. As the old fluid is purged the fluid will eventually change from dark to clear, with maybe a little amber tint. Sometimes I also dump the dirty fluid out of the catch jars as I near completion to observe that the fluid going into the jars is clean, but since my cars get a flush every two years, the old fluid is usually barely dirty.

Duke