Cannot remove master cylinder

[Jimmyvonviggle]

I’m having a little trouble removing the master cylinder. I undid the two hard lines and the two bolts that hold it on. The thing seems to be welded on by years of rust. I sprayed some PB Blaster and WD40, and let it sit for 2 days. I’m trying to be patient, but is it ok to wack it with a rubber mallet?

[Mark D]

I’m having a little trouble removing the master cylinder. I undid the two hard lines and the two bolts that hold it on. The thing seems to be welded on by years of rust. I sprayed some PB Blaster and WD40, and let it sit for 2 days. I’m trying to be patient, but is it ok to wack it with a rubber mallet?

I'm pretty sure I had to tap mine a few times to break it loose from the servo/booster when I swapped it out on my car a few years ago. There is also a little notch in the bottom side of the servo (meant to be a drain) that also works as a location where you can wedge in a little flat blade screwdriver to try and pry the master away from the servo.

Here's a pic from after I got the master pulled off my car where you can see that little channel on the lower side.
http://dmctalk.org/attachment.php?attachmentid=29997&d=1407726834

[Jimmyvonviggle]

Turns out if the rubber mallet you are using doesn’t work use a bigger one. At what point do you replace the master, or can the old one just be cleaned up?

[David T]

To reuse the old master cylinder the interior of the bore cannot have ANY pitting and you have to find a rebuild kit. Typically if the master is leaking it is pitted and that is what ruined the seals and caused the leaking. If the master is leaking you have to figure all of the calipers need to be rebuilt too. Once the brake fluid gets corrosive it ruins all of the metal in the system. If you have a 5-speed you should be checking the clutch system too. To avoid such an expensive repair the brake fluid should be flushed and replaced every other year.

[opethmike]

Turns out if the rubber mallet you are using doesn’t work use a bigger one. At what point do you replace the master, or can the old one just be cleaned up?

Is it the original? If so, absolutely replace it. The rubber inside of it is going on four decades old and if it isn't leaking yet, it sure will soon.

[Jimmyvonviggle]

Ok after some thought (and thanks to your suggestions) ill definitely replace it. Just reviewing different vendor options. I have now been removing as many hard lines as possible and cleaning them out.

[opethmike]

Ok after some thought (and thanks to your suggestions) ill definitely replace it. Just reviewing different vendor options. I have now been removing as many hard lines as possible and cleaning them out.

Just get one from Houston or MW; they have the proper proportioning.

[David T]

You do not have to remove the hard lines. They can be flushed out leaving them in the car. You can do more damage removing them.