Problem Bleeding ML-270

[Mark A]

I have just had the car back from a local repair shop and I noticed that the brake pedal feels a bit spongy. I was just about to bleed the brakes when I noticed that the rear bleed nipples have been butchered. Any ideas how would be the best way to get them out & replace them ?

Cheers,
Mark

 

[wireman]

Very carefully, you must not snap one off.

Get replacement nipples before you start, beware that some models and makers have longer than usual nipples, if these were fitted originaly the normal type will not sit in the hole deep enough and will leak. You will also need some new fluid, dont use stuff thats sat in a can with the seal broken it might be contaminated even if it was stored carefully. About 1 litre should be sufficient to flush the system as well as change the entire systems contents.

Here's my sugestion to remove the old ones.

Fluid will leak out onto the floor (and you if you let it) whilst this operation is undertaken.

Wire brush as much of the crud and rust from the exposed theads on the nipple as you can. If you wish spraying some kind of easing/penetrating oil onto the job some days before you takle it may help, but beware that oil and fluid must not mix not even slightly, not ever ever full stop. If you do use it clean up before you start removing the nipples.

Use a small steel wire (nail pop rivet etc) that fits snugly inside the hole in the nipple, this will prevent the nipple colapsing as you grip the nipples end with self locking pliers. make sure that the grip is good and firm before you attempt to unscrew the nipple.
If its rusted down the hole use a suitably sized small twist drill to clear out the hole. The shank of the drill may be a suitable anti crush pin.

Dont force it or bend it as you attempt to turn it, if it wont turn remove the grips etc and tap/hit firmly on the open end with a small hammer, hopefuly this will shock the sized threads and allow you to rotate the nipple once the pin and grips are back in place.
If its very stiff whilst rotating try rocking it back and forth to ease any corrosion in the threads away. Take your time and dont try to be a hero with strong arm tactics, you will just mess it up and then the caliper will be in need of an expert machinists attention to get the remains out without damaging the hole or its threads.

Clean out any debris from the hole once the old nipple is out. Fit the new nipple asap to minimise fluid loss. Allowing a little fluid loss will keep any crap from falling inside the caliper.

Placing an opened out cardboard box on the floor beneath the caliper will help prevent any lost fluid from messing up the floor.

Have a bucket or watering can of slightly soapy water handy to rinse any spilt or splashed fluid from the bodywork. Mind your hands and clothes, dont touch the bodywork with fluid on them.