Hello All,
I am replacing the master cylinder. The new one does not come with a reservoir. How the heck do ya get the old one off and put it on the new unit. Thanks for any help. Is there anything else to know about replacing the Master unit?? Thanks again!!

d

danio -

You got some good posts, especially about bench bleeding the new MC. Unless you are prepared to go ahead with a system bleed or flush, as I am usually not, there is a way to do the job without a system bleed.

Do the job such that the moving of the lines from old MC to new can be done real quick. As I recall, I loosen slightly the two lines and remove the mounting nuts from the old MC, it'll stay there w/o nuts removed.

Then hold the new MC nearby and trade off the lines PDQ. (PFQ if you are of the younger generation.) Finish the job and clean thoroughly. Remember that brake fluid eats paint.

Then either do a front pad replacement (as I do), or go to either front wheel and push the pads back away from the rotor as if you were going to do a replacement. This forces fluid back into the MC, enough to get out the small amount that got in during the MC replacement. Remember to pump up before driving off, unless you need a charge of adrenaline.

If that won't work for you, like if you haven't the time, try to do the MC job when the car can sit overnight afterwards. The air bubbles will be in the vertical lines and will likely float up into the MC and be gone by morning.

Good Luck,

Bob

:>)

The resevoir is seated in two O-rings. To remove it you need to pull it up while gently rocking it from side to side (careful not to break off the (2) nipples. To reseat it apply a coat of brake fluid to the O-rings and press it back in. Check the O-rings for damage, Replacing them may save you a problem later.

You need to prime the new cylinder before installation, this displaces air in the cylinder and reduce the need for brake bleeding. There should be instructions with the new cylinder regarding priming. If not then the Hayne's book explains it.

The reservoir just pops off the old master cylinder. Use a screwdriver
to gently pry up on the reservoir until it comes out. You MUST bench bleed
the new master cylinder before you install it on the car to prevent injecting
air into the braking system and to lubricate the seals in the new cylinder.

To bench bleed the new master cylinder, install the reservoir onto the cylinder
and fill it with fresh clean brake fluid. Hold the cylinder upright and remove the plastic caps from the outlet holes on the cylinder. Using a wooden dowel or other blunt object, gently press the actuator in a few times to force brake fluid out through the outlet holes to remove air from the cylinder. Reinstall the plastic caps while you install the new cylinder into the car. Reconnect the brake lines to the new cylinder.

DeWayne

I would add to what the others have said that you will probably need to bleed the whole brake system. Unless you are really careful (lucky?) you will get a little air in part of the system. Actually this can be good. This will give you a chance to flush out the old brake fluid and replace with fresh.

To "Do it Right", I agree it would be a good thing to bleed the entire system,
but I did not feel that bleeding the system was necessary when I installed my new master cylinder. It's been so long ago that I don't remember if I taped the ends on the brake lines or not, but I had plenty of hard pedal and the brakes worked fine. It was one of those emergency repair type jobs because the pedal was going almost to the floor with the old cylinder (internal bypass condition).

If the new master cylinder isn't bench bled, then you're asking for trouble because air will get into the system.