How hard is it to replace a Master Cylinder?

[WBBulldogs]

It completely went out today on a really busy road. Thank god I recently tightened the E-Brake. The bad part is that it was snowing today too! ARGGHHH! Almost slid through a busy intersection but I used E-Brake and 1st gear to stop me.

Anyways, how hard is it to replace a master cylinder? Do I need any special tools? Final question, the brake fluid that's in there looks black and horrible. Should I flush the system while I'm at it?

[Guest]

It's not hard.. I'd flush it if it's real black.. no special tools unless you have no help bleeding the brakes. Be sure to bleed the mc first though.

[info4all]

It's is actually really easy. I would suggest going to your local auto parts store and purchase the master cylinder. It should come with instructions on how to remove the bad MC, detatch the fluid holder thingy (stop me if I am getting to technical :lol, bleed the new MC, and re-attach the MC. The MC should also come with the kit (hoses, clip, and hole puggers) to assist you in bleeding the MC. I would say that a vice would be very handy in the bleeding process since you will want to keep the MC level while you slowly depress the plunger (as to not create additional bubbles in the fluid). A second person is handy when bleeding the brakes but if you are in a crunch you can do it by yourself if you have a stick the right length.

This is a bit of a short cut so you won't have the best brake pressure possible but it will get you around. When you reattach the brake lines to the MC if you depress the brake pedal and hold it there with a stick and then add fluid to the lines (if they are not full) and attach them the car should have plenty of pressure to stop the car comfortably. To get the best brake pressure you should bleed the lines every time you crack (unscrew) the brake line.

Hope this helps.

[Tom]

It sounds like somebody put automatic transmission fluid in the master cylander, they do that sometimes getting the fact that you can use transmission fluid in the power steering, master cylenders rarely good out all at once like that and the built in two chambers, one to the front wheels and one to the rear wheels is supposed to prevent everything going out at once, you may have to replace everything, at least a large flush of everything.

[Guest]

FYI, I went through 3 Autozone remfd MCs in less than a year. Granted, they were under warranty, but I finally got fed up and picked up an OEM from FMS.. that was over a year ago.. I haven't tried NAPA, but am told their remfd mc are pretty good.

[miami man]

dj is right, my autozone mc did not work well

[lilred]

i am not going through autozone anymore. they take to long to get stuff, it doesn't last long. The only thing i get from autozone is fluids and car care stuff. I have gone through napa and there stuff is great.

[WmWatt]

A 10mm flare wrench is a good idea, ie. a box wrench with a slot so it can go over the brake line. A few applications of some sort of penetrating oil such as WD 40 should help loosen the nuts (aka fittings). They have to be pretty tight to make a good seal because of the high pressure in the brake lines.

www.ag384bn.bravehost.com/braketips.htm has a bunch of info I learned when replacing all the brake line on my Festiva last summer.

[WBBulldogs]

How do you remove the connector that goes from the master cylinder reservoir to the sensor?

[WBBulldogs]

Okay I got the connector off. So I should get a 10mm flare wrench?

EDIT: I was wondering the size because 10mm seemed like it was a little too big with my regular open-end wrench.

Also should I use a blowtorch to loosen the nuts on the master cylinder?

[WmWatt]

I'd buy the flare wrench that you think is best and exchange it if it's not the right size. At times like this a bicycle comes in handy.

I did not use a torch anywhere inside the engine compartment. It took a while but penetrating solvent and the flare wrench eventualy got all the fittings off the master cylinder for me. I also use a small wire brush and a broken hacksaw blade to help clean nuts and fittings I'm trying to get loose.

[WBBulldogs]

Well I got the new master cylinder in and bled the brake system. The flare nut wrench is really worth it unless you feel like stripping the nuts on the brake lines that go to the master cylinder. None of the bleeder screws were rusted so I just sprayed some WD-40 on them and let it soak for 5 minutes and loosened them with an 8mm wrench. Took it for a test. Works great.