brake flush plug keeps popping off

Very strange problem... noticed brake fluid low, checked for leaks. Noticed that one of the two brake flush rubber plugs was not on in the driver side rear caliper. Plugged it up, filled it up, drove around. Notice that the plug popped off again. Tried it a few times and it seems like everytime I drive the car, the rubber plug decides to pop off and leak a tiny amount of brake fluid. Anyone know what's going on? Planning on going to the dealer for a flush next week and maybe have them check it out as well.... getting ready for them to tell me that it's because my car is Turbocharged lol...

Are you sure the brake bleed fitting (which keeps losing the rubber cap) is tight? Sounds like it's not. (Not sure of your background, so no offense if this is too basic, but it would cause the symptoms you describe). I would try tightening it just to be sure. Regards, Jeff.

None taken. Thanks for your input. The car hasn't been bled since I owned the car and I've only recently noticed it. Will check tonight to see if the nut is tight.

+1 for checking the bleed screw. Also, that screw does not take a lot of torque.

I think Jeff is right. It sounds like fluid is getting past the bleeder screw when you apply the brakes and filling up and popping the dust cap off. Is the little rubber cap wet inside with brake fluid? I would try to give the offending bleeder screw a snug down. Don't get all Conan with it, I think the recommended torque is 6-9 ft-lbs, which is pretty low. Chuck

Thanks for posting the torque spec. I was able to check it out this morning and it was exactly as suspected, loose bleeder screw. Interestingly, the brakes were never flushed since purchasing the car over a year ago, and haven't had any problems until now. Must not have been properly torqued by whoever bled the brakes before me.

Good to hear the problem is resolved. A noob question here, we're all talking about the screw that controls the bleeding of the valve, not the screw that holds the whole valve assembly in the caliper, right? Can that whole screw assembly be loosened by someone who doesn't know what they're doing while bleeding the brakes?

Well if the rubber cap was popping off because the fitting was loose then you were also sucking a little bit of air BACK into the line when you released the brake. You need to do a good bleed to eliminate those bubbles.

Yes, we're talking about only the bleeder screw. Once tightened, the leak stopped. Kehr: Great point. The system definitely should be flushed. Trying to decide if i want to pay the dealership $200 to do it, or buy fluids/bleeder and do it myself.

Kehr: Great point. The system definitely should be flushed. Trying to decide if i want to pay the dealership $200 to do it, or buy fluids/bleeder and do it myself.[/QUOTE] Notquite; Buy yourself a Motive Power Bleeder for about +/- $50 and do it yourself

i checked 2 jugs of brake fluid @ the dealership is 80 bucks.... almost worth just getting it done and not have to deal w/ waste disposal lol... you guys using super blue? or OE?

lots of guys swap between super blue and gold... (so they can determine that the old stuff is out)... potential "warranty issues" if you go to dealer w/ blue in there, so they swap back gold before that..

You might want to read thru the following threads regarding potential warranty issues with the Super Blue: http://www.planet-9.com/cayman-boxster-competition/27619-ate-super-blue-problems.html http://www.planet-9.com/cayman-boxster-competition/27777-super-blue-problems-2-a.html http://www.planet-9.com/cayman-boxster-competition/28656-super-blue-problems-3-a.html It's too bad that we have to worry about potential warranty issues just because of some blue dye, but there are some other alternatives besides the OEM fluid, including: ATE Super Gold, Pentosin RBF, and Motul600 RBF - if you are planning on tracking your car.

I don't think you need a full flush but certainly a good bleed. If you have any concerns at all about warranty then DON'T USE BLUE. Be one with your car...do it yourself. It gives you a great feeling of accomplishment. An occasional visual inspection is a good thing to do anyway. I put the waste in the drain pan along with my motor oil and dump it for free at the quick change place up the street.

Pete, I'm glad too, that the fix was identified, and so simple. And I agree with the above comments suggesting there could well be air in the system. Definitely, its possible to loosen the entire fitting, they're meant to be replaced if needed (or changed to a speedibleeder type). It would be pretty obvious, fluid would be coming out around the threads instead of the end of the bleeder. If the whole assembly is loose where it threads into the caliper, and you tighten the proper portion of the bleeder you are effectively tightening the whole thing, so it shouldn't leak. But, the fitting should be torqued into the caliper at a higher value than the bleed screw so that during normal bleeding you don't accidentally loosen the whole thing and create another path for air to suck back into the system, when things a working as designed only the bleed screw should move. In retrospect I think that 6 to 9 ft-lb spec I found is probably the torque for threading the whole fitting into the caliper. It just sounds too high for the bleeder screw, and you don't want to break one of those, that would be a hassle. They just need a little snugging to hold pressure. I mean the OP, notquitefob's screw was probably only finger tight, since it backed out, and it was working OK, at least for a while. Chuck

There is another issue here. Brake fluid absorbs moisture and going a year or more probably is not good. Water boils at a much lower temperature than brake fluid. A good flush and bleed is therefore good all around. You will sure need to do it if you track the car. Ed

Sorry about the misleading information also. I finally took a close look at the calipers today and realized my mistake. Now my question is, how do you get those bleed screws into the caliper if the hex fitting is only for opening the valve?

Not sure if I understand your question completely Pete. The bleed screw threads directly into the caliper, if you loosen it a little it gives a path for the fluid to escape, if you loosen it a lot it comes completely out of the caliper, just like a regular screw or bolt out of a threaded hole. When you tighten down the bleeder screw the conical portion of the screw plugs off the fluid by mating to a matching area machined into the caliper body. There is no valve per se, it acts more like a threaded plug blocking an orifice. Boy I hate to be the one to explain this after handing out BOGUS information earlier in the thread ,but I'm trying Chuck

Got it. I see the little hole at the bottom of the photo you posted of the screw, that's where the fluid would go in to exit at the top. Thanks Chuck!

Outstanding, glad you got it Pete! I found this little picture that makes the path of the fluid even more obvious for anyone who is interested: Speed Bleeder Picture at: Russell Performance The stock Porsche version wouldn't have the ball and spring on the inside, just an empty tube area, but the fluid path would be the same. All you have left to imagine is the cone shaped area down in the caliper where the screw mates to and blocks the fluid. Chuck p.s. I was a good netizen and didn't hot link the picture.