I snapped both of the bleed nipples on Felicity's front calipers (Felicity being or 1992 Panda Parade). I'm a ham fisted old codger and snapped both rear ones too! - Is that some sort of a record? The rear cylinders were actually leaking very gently so needed changing anyway. They are not expensive and there are some real bargain prices around if you're not in a hurry so probably not worth the hassle of struggling with the old ones.
The calipers though are a bit more pricey and Felicity's weren't leaking but the nipples were really really rusted in! If you take the caliper off it's carrier and push the piston right back in (watch for the master cylinder overflowing) then you can remove the dust rubber. Hold the caliper in your hand so the piston is facing up and gently pump the brake pedal (Mrs Jock is very good at this) 'till the piston "pops" out of the seal. You might want to clamp the brake flex hose to that wheel at this point to stop all the fluid from the reservoir leaking away. You can now take the piston right out and have a good look at it to see if it's corroded/damaged - if so you might want to buy a new caliper anyway so that solves the problem of the nipple being broken on the old one.
If you find the piston to be in good condition (and because it wasn't leaking before, I took a chance on the seal being in good order) pour some new brake fluid into the caliper (I like to empty out the old stuff first) until it "brims". Now take off the flex pipe clamp, if you used one, and give a couple of pumps on the brake pedal just in case some air got into the pipes whilst you've been messing about. (keeping enough fluid in the master cylinder so that air doesn't enter the system but you want it fairly empty because of what you are now going to do). So you are now holding the caliper in one hand, like a cup filled with brake fluid, now just gently push the piston back into it. As it initially enters the caliper bore some fluid will be expelled to dribble over the sides. This is good because all the air is excluded. - It's quite messy though so you want a tray underneath to catch the fluid and a nice big rag to wipe you hands on. - Only a small amount of fluid is expelled though because almost immediately the piston will enter the sealing rubber ring and then it chases the rest of the fluid back into the system. Push it fully home and replace the dust seal. A wee spray with some brake cleaner to clean up the outside of the caliper and you're ready to reinstall it on the carrier.
This all sounds a bit involved but actually it's very simple and works very well on most single pot calipers. There is an argument about chasing fluid back through ABS equipped systems as you might chase a wee bit of dirt back up into the ABS module? All I can say is it hasn't happened to me yet. But maybe I'm just lucky?
You can actually bleed cylinders the same way. After checking that the cylinder/piston and fluid seal are worth saving - so you need to pop the pistons out and clean everything up - Reassemble without the dust rubbers and, with your hands (if its a two piston cylinder) keep one piston pushed well home into the cylinder (but not so far that you cover the fluid feed port). Now take the other piston and enter it into the cylinder just far enough that the seal enters the bore. Now get a helper to gently pump the brake pedal. The first piston you reassembled must remain well into the cylinder so it's seal can't leak the other one you let "ride" against your finger so that, as the pedal is pushed down, fluid can get past the seal. Keep enough pressure on the piston so that when the pedal stroke is completed the seal will stop any air being drawn into the cylinder on the return stroke of the brake pedal. Just a few strokes usually gets the job done and you can push the piston back into it's bore and put the dust rubbers back on. It helps too if the end of the cylinder which you are allowing fluid to emerge from is higher than the other end (being as the air will rise to the top!) This is usually managed with a bit of jacking up of the vehicle, but a satisfactory result can be achieved so long as the cylinder is horizontal. Bear in mind though that air will always rise, so if you're dealing with an older style single piston sliding cylinder design you sometimes have to think of "inventive solutions" to achieve the desired angle on the cylinder. I find that with the "bleeding" piston almost fully out of the cylinder, you can angle it slightly downwards so that the fluid is expelled at the top thus ensuring no air remains in the cylinder.
I've messed about with old cars for years and I've bled brakes this way many times and never had a problem. You do want to dismantle the piston and cylinder first and clean it up before you start otherwise dirt or crusty corrosion can damage your seals.
Because you will be unfamiliar with doing this you'll probably find the first time you do it takes a bit of time and be prepared to get a bit Mucky - keeping you hands off the paintwork 'till you've washed them! Doing a caliper this way is quite quick but drum drakes are a bit more involved because you really want to get the linings out of the way so they don't get contaminated with fluid so quite a bit of dismantling needed.
Need I say, If you buy new components, remove the nipples and smear their threads with some anti-seize before bleeding!
Finally, I have to say, if you decide to have a go at doing it this way, Don't unless you are a confident DIYer. I would be confident that I could show you how to do this safely but as I'm here and you're there (wherever "there" may be) I can't see what you're doing or if you are doing it safely. A brake malfunction can kill you and others - never take chances. It's good practice, whenever working on brakes, to frequently check master cylinder fluid level for several weeks after and take a careful look at the components you've been working on immediately after you finish and then again soon after you start using the vehicle again.
