How remove seized bleed screw

[mgcjag]

Hi All......need a bit of help.....i have a bleed nipple seized in a caliper......tried all the usualls plus gas, atf/acetone and it just wont move........whats your thoughts of putting the whole thing in tbe oven or freezer...caliper is cast nipple is not.....what will give me the best option for expanding the cast and not the screw....bit of wishfull thinking really befor i need to get it drilled out...thanks... Steve

[ALAN COCHRANE]

Steve

I had exactly the same problem with one of my calipers.
I eventually resorted to drilling a small hole through the body of the bleed nipple with my pillar drill. I then used successively larger drills until I could fit a small diameter drift in the hole I then tapped the drift with a hammer and the nipple turned and came out very easily.
There was very little signs of any rust on the threads but obviously enough to seize it in the caliper.
I fitted stainless steel nipples after this episode.
Hope this helps

Cheers

Alan

[mgcjag]

Hi Alan...thanks for the reply....i have enough grip on the bleed screw i have a small pair of stillsons on it i just dare not apply and more pressure as think it will snap.....i havnt held back ive given quite some force......

[JagWaugh]

Hi All......need a bit of help.....i have a bleed nipple seized in a caliper......tried all the usualls plus gas, atf/acetone and it just wont move........whats your thoughts of putting the whole thing in tbe oven or freezer...caliper is cast nipple is not.....what will give me the best option for expanding the cast and not the screw....bit of wishfull thinking really befor i need to get it drilled out...thanks... Steve

Putting it in the oven won't do the seals or the marital bliss any good. You could try putting it in the freezer, or better yet, if you can get some local (ice cream shop which sells cakes), then trying some dry ice might help.

Put the Stilson down, use a long socket of the correct size and hold the rachet so that you aren't bending the bleeder along its C/L.

If some madman has put something like loctite on it then only heat will help. Best is a small point flame from an Oxy torch applied only on the nipple - make it red, it will cool down while you are turning the torch down and putting the other flames out. While the nipple is still about 300-400 C, put the socket on and remove it.

It may break off at the hex, then you'll just have to drill and use an extractor or such.

[christopher storey]

Steve : I don't think there is a short cut to this. Personally, I would take the caliper off the car, extract the pistons and seals to avoid heat damage, and then apply heat locally to the bleed screw area with a blowlamp . MAPP gas is best if you have such a blowlamp, because you can get a lot of local heat quickly , but otherwise propane/butane will do.

[ALAN COCHRANE]

Steve

I also had plenty of leverage with mole grips but with no success. The act of hitting the drift with a hammer provided the sharp shock required to break the rust bond between caliper and nipple. I've used this method twice, both times successfully. It doesn't require much of a dunt with the hammer to release the nipple.

Alan

[mgcjag]

Caliper is off the car....piston and seales removed....couldnt use a socket as the nut part is already damaged....someone had this problem befor.......if i apply heat direct to tbe nipple will this not expand it in the caliper and make it enen tighter.....thanks Steve

[JagWaugh]

Steve,

If the problem is that something is binding in the threads (rust, loctite, sealing compound, snot) then heating will expand the nipple, breaking the bond or crushing the rust. It will expand the nipple, but this will only be temporarily.

If the hex was already trashed before you got to it there may be a bit of swarf in the threads and the PO just tried cranking down harder rather than taking the nipple out and finding out why it wouldn't seal in the first place.

[mikey1]

Steve, I would heat the nipple with an oxy-acetylene torch. Blow lamps are often just not hot enough. Yes, it will cause the nipple to expand but what expands then contracts and it is this movement, combined with burning the corrosion which does the trick. Good luck. On another matter I have just fitted the chrome wires you sold me a couple of years ago and they look great,

Regards,
Mike.

[mgcjag]

Hi All...latest update....welded a nut on the end of the nipple so i could fit a socket...heated up only using a blow torch and succeded in snaping the nipple flush with the caliper.....so off to an engineering shop monday to drill out and re tap......thanks for all your help.... Steve

[driver]

Going off subject here a bit,on changing the brake pipe from brake master cylinder to brake servo i noticed that
the fittings are not 3/16bsp has is the usual size for copper brake pipes,could i use a reducer to 3/16 has the larger size copper pipe seems unusual.Looking at the etypes at the nec last week it appeared to be standard 3/16.having checked the size of the existing pipes they seem to be an non BSP size what size i am not sure.
Any thoughts or info on this ?

[driver]

Going off subject here a bit,on changing the brake pipe from brake master cylinder to brake servo i noticed that
the fittings are not 3/16bsp has is the usual size for copper brake pipes,could i use a reducer to 3/16 has the larger size copper pipe seems unusual.Looking at the etypes at the nec last week it appeared to be standard 3/16.having checked the size of the existing pipes they seem to be an non BSP size what size i am not sure.
Any thoughts or info on this ?

[Rustyred]

For those who want to know, most bleeder nipples seize by not having a cap over the top of the bleeder hole.
Open nipples allow water ingress into and down the bleeder hole, allowing corrosion to form under the threaded section of the nipple. The little bit of brake fluid in there, makes it worse due to it being hydroscopic. (ability to absorb moisture)
Drilling the nipple out is the only real way of making sure there will be no damage to caliper. I have also seen where the nipple is overdone, and swells the section around the hole, but those who work on them will still try and drive that tight nipple in, again causing damage to the threads on the caliper.