ThunderC4S

What is involved in replacing a seized brake caliper bleed valve (nipple) on my 964 Brake Caliper (rear) ?

Does it need to go to a machine shop or do I need a new caliper ?

John

Rocket Rob

I would approach this as being the same as any other rusty or frozen bolt/nut. First try soaking the bleed nipple with an penetrating oil for several days and then try turning it again. If that doesn't work, I would get a good set of Vicegrips and clamp onto the nipple and turn it. If you are lucky, it will loosen and you can unscrew it and replace it. If it doesn't turn, then you haven't lost anything since the nipple is gone anyway.

springer3

Mechanics swear by PB Blaster, a spray-type penetrating oil. Cycles of heating, cooling, and gentle torque cycles will loosen almost any thread. Rust bonds are strong but very brittle. Each cycle of heating, cooling, and torque application will break loose just a little bit of stick, and soon the entire thread will start turning.

The mistake, of course, is to get frustrated and try to over-power it. That will damage the wrench flats or break off the part. Then you need a new caliper or a trip to the machine shop. The trick is to apply enough torque to break loose just a little bit of rust, but not enough to cause damage. The tightening torque for the fastener is a good place to start - that should cause no damage. If that does not work, ratchet up the torque, heat, and cold (used to spray freon before anyone heard of ozone depletion). Liquid propane (LP) is a great refrigerant. Get the liquid by inverting your portable propane cylinder. Watch out for the fire hazard and freeze burns on your skin, and don't inhale the stuff.

Be sure to get a professional-quality box-end wrench. Hobby-shop wrench brands do not fit as well, and are more likely to round the wrench flats. I have a personal experience with a Snap-on box-end removing a 10 mm hex-head bolt after I had already rounded the head using a Craftsman wrench. Professional tools are more expensive, but Porsche mistakes are very expensive. Get good tools, or take the car to someone that does.

A trip to a professional mechanic might be the cheapest way out. Some of those guys take pride in being able to remove something after a hobbiest admits failure.

Good luck - report back on what worked.

MisterRisky

In the words of Mr. T, "There's only one way to get that nipple off, Sucka. PAIN! That's right. You heard me. PAIN!"

Oh yeah, I second the PB. Be careful with heat, however. If you are going to use heat, get the caliper drained and up in a vice so you can really work on it. Then try heating only the tip of the nipple. Keep in mind that if you put the flame to it you run the risk of messing up all the little rubber bits on the inside and the caliper which will need rebuilding. With that in mind I would go the route of PB and torque. If you go so far as breaking the nipple off you can have it drilled out at a machine shop.

So what shape is the nipple in right now?

Good luck.

DAVISRILEY

Last time this happend to me I got lucky. Soaked overnight, and loosened with a long 12 point socket over the top of the bleeder nipple just to loosen. The went at it with the line wrench. And yes, I will 3rd the pb.

JasonAndreas

In addition to all the suggestions above, DO NOT USE A WRENCH! Flared, twelve-point, with teeth, or other-wise, you really, really want to use a high quality six-sided deep socket. Even when you're just trying to break open the line to bleed the caliper and you are unsure if the valve has ever been opened before, you will want to use a socket. It will dramatically reduce the chances of rounding the valve and you can do it without spilling a drop of fluid. Use a wrench for bleeding after you know that you can actually open the valve. The other advantage is that you won't slam your hand into the brake disc and the splash guard and the caliper trying to do this with a tiny-*** wrench.

ThunderC4S

I found a local distributor here for the PB Blaster in Australia - Will give it a try...

Thanks !

MDH

I had one bleeder valve that was absolutely frozen to the caliper. The problem I found was not rounding off the corners of the valve, but breaking it off completely. These things are pretty soft. I succeeded in breaking one off flush with the caliper. In the end, I drilled it out myself with a hand drill and and a smaller diameter drill bit. The material that was left on the sides of the hole, I was able to pry off the threads and the thing pulled right out. I was surprised how easy it went. Replaced it with a new one and all was well.