Bleeder Screw Hell - Help...

[Mike Feinstein]

Completed my 930 brake upgrade and all went smoothly...I thought. I bled the system a few times to get all the air using Castrol GT-LMA Dot 3 and Dot 4 fluid. I used this to bleed the system ($4/liter) and then intended to do a final flush with ATE Blue.

Well, I pressure bled the system, including the clutch, and all went fine. Nice firm pedal. Spent the day with the kids and this evening, I went out to the garage to put the wheels on and try it out. I noticed that every brake bleeder screw had seeped...including the clutch bleeder...as well as some seepage around two or three of my hard line connections....hmmmm, maybe I didn't tighten things enough. So I tightened all my line connections and so far they seem OK. I rebled the system for fear that I had air enter and then retightened the bleeder screws, very snug...more than I normally do. Here's the mystery...when I put the little rubber cap on the bleeder screw, brake fluid would start to visibly leak out around the base of the bleeder screw....not through the top, but around the base...and not just one...but all of them.

The only thing I could suspect was the fluid...grasping at straws. So, I just did another complete flush, brakes and clutch, with ATE Blue. Seems better but I'll pass judgement after it sits over night. These are Porsche 930 Brembo calipers that are in excellent shape. I'm completely baffled . Any ideas???

[Mike Feinstein]

OK...my over-tired gord just came up with an explaination. Try this...after bleeding, there's probably a cc or two of fluid which remains inside the bleeder screw after it's tightened down (930 bleeder screws are big). When I pop the sealed rubber cap on, it forces fluid down the bleeder screw, but since it can't go back into the brake line, it is forced out the hole and up through the threads to the surface. What bothers me is that the threads aren't sealing better...but there is definately no leaking through the top of the bleeder screw, so I guess they're doing their job. Would it be adviseable to wrap the bleeder screw threads with teflon tape? I made a pin hole in the top of each rubber cap and soaked up the juice inside of each screw and it seems to have helped.

Does this make sense? Anyone with 930 brakes ever experience this?

[feelyx]

Mike,
The point on the bottom of the bleeder screw makes the seal... wrapping the threads will do nothing for you.
Tim in Sac

[911nut]

Clean all of the areas that leaked with brake cleaner or mineral spirits and make sure everythings good and dry. Then tromp on the pedal a few times to make sure all's well.
I've had this happen too. Seems like it takes forever to get rid of that fluid and actually see if you got everything tight enough.

[Mike Feinstein]

Ahhh, glad to hear I'm not alone. I did exactly what you recommend late last night, and this morning all is dry and the pedal is hard as a rock.

All is good!

[89911]

Mike, this has happened to me also. The valved seem to seep right at the screw-caliper junction. I've tightened these as much as possible. I would think new bleed valves would cure this since the area's involved may be wearing from repeated bleeds. It stops after a while but some small seepage is still visible.

[GeorgeK]

I always empty the bleed screw with a piece of paper wipe rolled into a "point" that I push in the screw to take all the fluid out of the screw. Never had any dampness around the threads.