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Stuck master cylinder
- Thread starter Leavitt
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Welcome to the Forum, Leavitt -
Assuming they're stuck due to corrosion, you'll need to soak them for a good while in PB Blaster/WD40/etc., maybe apply a bit of heat, and then VERY CAREFULLY pop the pistons loose with compressed air, through the port where the line connects. Be sure to wrap the cylinder in a thick towel to catch the piston, and be sure to aim the opening away from that window opposite the bench vise! WATCH YOUR FINGERS, and good luck!
/ubbthreads/images/graemlins/cheers.gif Mickey
Assuming they're stuck due to corrosion, you'll need to soak them for a good while in PB Blaster/WD40/etc., maybe apply a bit of heat, and then VERY CAREFULLY pop the pistons loose with compressed air, through the port where the line connects. Be sure to wrap the cylinder in a thick towel to catch the piston, and be sure to aim the opening away from that window opposite the bench vise! WATCH YOUR FINGERS, and good luck!
/ubbthreads/images/graemlins/cheers.gif Mickey
Alan_Myers
Luke Skywalker
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Hi Leavitt,
Maybe you already know, often when MCs stick there is corrosion inside that's damaged the surface so a new piston will wear and leak very quickly. So, it's important to check the inner surfaces very carefully for any roughness or damage. If there is some and it's very minor, honing might be an option. If the corrosion is at all progressed beyond "minor", replacement or re-sleeving might be necessary. (www.applehydraulics.com can install a sleeve in most MCs and SCs). Hope there isn't a problem with yours.
Grease works well for really stuck hydraulics. It just means a thorough cleaning afterward to be sure no traces contaminate the brake fluid, but otherwise is a great solution. There are grease zerks widely available with a 3/8" fine pipe thread. I've used these for this purpose, after using a die on the zerk to cut new 3/8" NF threads. Works great and has unstuck things where nothing else would work.
/ubbthreads/images/graemlins/cheers.gif
Maybe you already know, often when MCs stick there is corrosion inside that's damaged the surface so a new piston will wear and leak very quickly. So, it's important to check the inner surfaces very carefully for any roughness or damage. If there is some and it's very minor, honing might be an option. If the corrosion is at all progressed beyond "minor", replacement or re-sleeving might be necessary. (www.applehydraulics.com can install a sleeve in most MCs and SCs). Hope there isn't a problem with yours.
Grease works well for really stuck hydraulics. It just means a thorough cleaning afterward to be sure no traces contaminate the brake fluid, but otherwise is a great solution. There are grease zerks widely available with a 3/8" fine pipe thread. I've used these for this purpose, after using a die on the zerk to cut new 3/8" NF threads. Works great and has unstuck things where nothing else would work.
/ubbthreads/images/graemlins/cheers.gif
Don Elliott
Obi Wan
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If you decide to send them for re-sleeving, make sure you send the pistons etc. as well. I sent just the body and when I got it back, it had not been reamed to the correct inside diameter. Talk to them first to make sure they will do it. Lucily, I have a neighbour who is well equipped with reamers.
OP
Leavitt
Freshman Member
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I used a idea I picked up from another site, I heated the master cylinders up in water below boiling for about an hour, and the came right out. I tried the grease gus method first and couldn't get them to move. I haven't had a chance to look at the bores yet to see if they are reusable. If the aren't, I can try some off of my parts car to see if they are better.