Brake changing procedure


#1

I have been doing car maintenance for years and have done many brake jobs on both disc and drum brakes. I have just acquired a 2006 Chrysler town and Country and the local parts dealer said that when I push in the piston to allow for the new pads I have to open the bleeder on the caliper and let the excess fluid out that way rather than just pushing it through the lines back into the reservoir like I have always done because the vehicle is equipped with ABS. I have never heard of this before and I have a Haynes book ordered but has not come in yet so I cannot consult them. This sounds bogus to me but I do not want to wreck anything either and find out the hard way that I was wrong. Any help in this area would be appreciated.

Thanks


#2

The Parts Guy Is Giving You Good Advice. Although You Can Probably Do This Job As You Always Have And Get Away With It, It’s Not Recommended. Why Chance It ? What’s The Big Deal ?

CSA


#3

I guess it is not a big deal but then I have fluid all over the place and it is just one more step to do. I bought a brake bleed kit to collect the fluid just in case I was wrong but I just hoped I did not need to do it for this job.
I am guessing the proper procedure would be to open the bleeder a turn or two, push the piston back in the caliper and then when it bottoms out tighten the bleeder up again?
Thanks for the help.


#4

Yes, but hold the caliper in a position so that the bleeder valve is at the highest point, and if you can, tighten the bleeder valve while you are still squeezing the piston into place, just before it hits bottom so that you don’t get air into the system.

Send a thank you card to your parts guy, he saved you a lot of money, or at least tell his boss about the good deed he did.

edit: added comment. Since you have a bleed kit, hook the hose up to the bleeder and then hang the cup above the caliper. This way, air cannot enter the system while you are squeezing the piston into place. With this, you wont need to close the bleeder valve while squeezing the piston in place, just tighten afterwards.


#5

Thanks for the help and the tip about holding the cup above the caliper to eliminate any air in the line. That is a great idea. For curiosity sake what would actually break if I did it the other way?


#6

Yep, this is a standard procedure since ABS became available. It prevents old fluid from contaminating the expensive ABS sensors. It would be in the factory manual but doubt it would be in the Haynes.


#7

probably check valves in line to prevent backflow


#8

The reason you do not want to push the old fluid back through the ABS unit is that any debris, water, rust particles or gunked brake fluid can easily get into the valving of the ABS unit. Once this happens all sorts of troubles can occur. I don’t think anyone is rebuilding ABS units or even providing a kit and instructions to DIY. So you would be buying a new unit – muchas $.

If you have not done it since the van was new, you should completely flush and bleed both systems at this time. So you might do this first before you retract the pistons to get the maximum flushing of the calipers.

HTH


#9

It’s never a good idea to push old fluid back into the brake lines and upstream components, never…With ABS, it becomes critical never to do this…I would use this opportunity to bleed the brakes and purge out all the old fluid from top to bottom. ABS can be charged with high-pressure fluid, so before you open THAT bleeder, educate yourself as to the correct procedure…


#10

The cup mentioned… do you have an old soda bottle rigged up to use as a bleeder? that works excellent too. that way the end never sucks air back into the bleed screw.

easy to make one. a clean, dry soda bottle. drill two holes in the cap. one with a hose long enough to go almost to the bottom of the bottle, one to vent out the top. 1/4 fill the bottle with some clean brake fluid. then crack the bleeder while compressing. when you are done all the expelled fluid will go in the bottle, and since the bottle has fluid in it it wont let air in the bleed screw. since you always have a little suck at the end. If done properly you dont get air in, and dont have to bleed the brakes afterwards.

The good thing about the bottle is you dont need to hold it up above, just near the caliper.

save it for later. it comes in handy.


#11

I didn’t like the thought of following the procedure either but it didn’t take long with a plastic water bottle that I held up with mechanic’s wire. Put a little brake fluid in the bottom of it and you won’t have a problem. I had some clear hose to connect to the bleed valve.

An extra five minutes wasn’t too much time to waste.