blake

I last drove the GT3 at a DE three weeks ago, and noticed this morning that their is a slight "dribble" of brake fluid out of the bleed valve on BOTH front calipers. It is a few millimeters wide but runs down about 3 inches like a bead of water on a window. I suspect one of three things: 1) my mechanic put in too much brake fluid in the reservior, 2) my mechanic did not tightly close the valve cover (?), or 3) my brake fluid boiled.

I just had my mechanic put in Castrol SRF just prior to the DE, so at least I know that the fluid was fresh. As for the DE, it was a very cool 55 degrees all day. I did, however, push the brakes very hard (yes, I'm working on that...)

Any ideas?

Thanks,
-B

insite

too much fluid in the reservoir won't do this; neither will boiling the fluid. BTW, you didn't boil new Castrol SRF, i promise.

i think probably one of a couple things is going on here. first, if the bleed screws were open even a little, your pedal would eventually sink to the floor if you press it and hold it. try this: press the pedal kind of hard and just hold it there for a few minutes. does it sink? do you see more fluid appear? if not, the valves are tight. check them anyway, just to be sure.

probably some fluid managed to get caught in the rubber nipples that cover the bleed valves. another possibility is that your mechanic gravity bled the system and let some fluid spill.

RJFabCab

It sounds like a messy clean up job to me.

If there's any question, check the tightness of the bleed nipples yourself, clean everything up, and then pedal pump the system to see if anything is leaking.

If your brakes functioned well, it's unlikely that you have a leak.

AW

In my experience, the only way to do this is #2

khaug

Ain't no way you're gonna have good brakes if a bleed screw is left even a little open, dood! Most likely, this was residual drool which occurred during the bleeding process and is inconsequential. No way can (a) Overfilling the reservoir, or (b) boiling brake fluid (VERY highly unlikely if using SRF!!) be responsible.

But do check the tightness of the caliper bleed screws yourself. They should be 'good and snug', but not 'Godzilla tight'. If you find they aren't snug, it's time to find a new mechanic!

Cheers!

blake

Thanks guys. I took it for a spin last night and the brakes feel spot on. I'll do a thorough check of the car going over the checklist that you provided just to make sure...

-B

Ahsai

Why don't you clean around the bleed valve and see if there's any more leak after that. Same thing happened to me once after a brake fluid change at the dealer and that scared the hell out of me. It turned out it's just a messy job.

Good luck.

- Ahsai

FixedWing

I had this problem on my 996 Turbo with PCCB brakes. They never faded but the force required grew as they became hotter and hotter. I have strong leg muscles. I found that I was able to increase the pressure to the point where the bleed screws would leak when torqued correctly. When they were over-tightened a little it was slightly better. PAG ended up replacing callipers until they found a set that would not leak. Mine were worse than what you describe and it happened on three of the four wheels. No one would believe it until they saw it.

For obvious reasons, I'm not that impressed with Porsche's callipers. I believe the real probelem was that the mating surface for the calliper bleed screw wasn't machined perfectly. It is a metal-to-metal surface and needs to be perfectly machined and smooth to seal tightly.

The other way this can happen is if the bleed screw is over-tightened. It can compress and warp the bleed screw. Then it might not seal properly.

Anyway, one thing to make sure you do is to wash off any extra fluid after bleeding them. Make sure you take off the caps and wash inside the bleed screws with water. Then you will be able to see if there is even the slightest leakage.

Stephen

chris walrod

Common causes of bleeder nipple leaks include overtightening, debris between the seating surfaces, worn bleeder nipple seats.

This happens on racecars often as these are loosened and tightened several times each day of racing. Sometimes just cracking them loose and retightening can solve weeping, or doing this several times to reseat the sealing surfaces.

The seat angles are generally machined 1 or 2 degrees differently from one another. Dissimilar angled surfaces provide a 'focussed' pressure area.

110 in/lbs. is plenty of torque.

All that said, your problem is more than likely residual fluid left in the bore of the bleeder nipple and simply was not cleaned out. Water will 'cut' brake fluid easy enough.

NJ-GT

I had my cap replaced, due to the same problem. I still use a paper towel with zip tie around the cap, just in case.

RJFabCab

Rad, let me get this straight... you zip tie the little rubber caps which cover the bleed nipples? What purpose does this serve other than to help contain a little spew mess?

Did someone say NIPPLES?

NJ-GT

I'm sorry, I misunderstood the post. The cap I referred to is the reservoir cap.

Fluid coming out of the caliper nipples, only two possibilities I know so far:

- Loose nipple. Easy fix tighten it
- Stripped out thread on the caliper. These are aluminum monobloc calipers, very light, but also a soft metal. I've no idea how to fix this problem, I would rather get a new caliper for my own peace of mind (if that was the problem).

Z06Kevin

I knew a girl once with loose nipples...