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Leaky Brake Bleeder Screws

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Old 01-28-2024 | 03:21 PM
  #16  
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It's a long shot, but verify that the rubber retention loop for the bleeder cap is loose under the bleeder hex and is not clamped in place.

If the bleeder's hex bottoms out on that rubber before the metal taper bottoms out then I could see that preventing the bleeder from seating properly. It's unlikely unless there's some tolerance issue with the bleeder or taper but easy enough to check: just make sure it's loose and not clamped in place.


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Old 01-28-2024 | 03:32 PM
  #17  
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Originally Posted by MrMoose
It's a long shot, but verify that the rubber retention loop for the bleeder cap is loose under the bleeder hex and is not clamped in place.

If the bleeder's hex bottoms out on that rubber before the metal taper bottoms out then I could see that preventing the bleeder from seating properly. It's unlikely unless there's some tolerance issue with the bleeder or taper but easy enough to check: just make sure it's loose and not clamped in place.

The rubber boots are installed after the bleeder screw is tightened down. I wish it was that simple.

Still leak free so far.

Last edited by Graufuchs; 01-29-2024 at 08:36 AM.
Old 01-30-2024 | 12:59 AM
  #18  
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Originally Posted by Graufuchs
Having an issue with brake bleeder screws sealing. I have already replaced them and (2) still are not sealing. I get a slight weep out of the threads around the new bleeder valves. It looks like it may have been an issue on one side before, as I had a little whitish fluid when bleeding one side of the front caliper.

Two replaced bleeder screws had corrosion on the base of bleeder screw (water). Anyone encounter this before? Does anyone have the part number for speed bleeder screws? (they come with thread sealant installed) (Base brakes 2008 3.6L)

I have the speed bleeder sealant on order to apply on threads, but looking for any suggestions or experience with a similar issue. Not going to use teflon tape, not going to be a neanderthal and torque them down to far.
i replaced all 8 bleeder screws in my last brake bleed (about 2 years ago). They weeped (like yours) for about 2 weeks, then stopped. At first i wiped them clean and after a week i gave up. Another week went by, the wet area did not seem to expand, i cleaned them up and it had stopped. To date, the areas are still dry. I supposed the brake fluid dried up that helped seal the weeping. Regardless, i am happy that the brakes stopped crying.
Old 01-30-2024 | 03:39 AM
  #19  
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Originally Posted by E39Nutz
i replaced all 8 bleeder screws in my last brake bleed (about 2 years ago). They weeped (like yours) for about 2 weeks, then stopped. At first i wiped them clean and after a week i gave up. Another week went by, the wet area did not seem to expand, i cleaned them up and it had stopped. To date, the areas are still dry. I supposed the brake fluid dried up that helped seal the weeping. Regardless, i am happy that the brakes stopped crying.
I’d suggest that what you and the OP are experiencing isn’t leaking bleed nipples, rather it’s residual brake fluid left in the internal bore of the bleed nipple between (ie above) the level of the taper seat and below the level of the top of the nipple where you’d attach the bleed pipe.

Once you’ve finished bleeding the caliper and applied the rubber bleed nipple cover, the fluid seeps out as the calipers get hot and the pressure builds up inside the rubber cap.

Once done bleeding, I always blast the bleed nipple inside and out with brake cleaner to ensure no brake fluid is present outside of the tapered sealing surface of the caliper/bleed nipple.

Allow the brake cleaner to evaporate fully before fitting the rubber bleed screw cover (or dry with paper towel)
Result ? No seepage or “leaks”.

Last edited by Atgani; 01-30-2024 at 06:03 AM.
Old 01-30-2024 | 08:34 AM
  #20  
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Perhaps. I always wiped the area clean and dry when I finish the job as I check on any leaks or weeping the following week(s) after I done the job. Good idea but not likely the cause. This doesn’t happen on my E39 (though it is steel/steel combination).
Old 01-30-2024 | 08:37 AM
  #21  
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Originally Posted by Atgani
I’d suggest that what you and the OP are experiencing isn’t leaking bleed nipples, rather it’s residual brake fluid left in the internal bore of the bleed nipple between (ie above) the level of the taper seat and below the level of the top of the nipple where you’d attach the bleed pipe.

Once you’ve finished bleeding the caliper and applied the rubber bleed nipple cover, the fluid seeps out as the calipers get hot and the pressure builds up inside the rubber cap.

Once done bleeding, I always blast the bleed nipple inside and out with brake cleaner to ensure no brake fluid is present outside of the tapered sealing surface of the caliper/bleed nipple.

Allow the brake cleaner to evaporate fully before fitting the rubber bleed screw cover (or dry with paper towel)
Result ? No seepage or “leaks”.
I cleaned the area quite well (including inside the port of bleed screw) and left the caps off, and I would still get a weep (from threads). Unfortunately that wasn't the issue. I had thought of that.

At this point 3 days later, I still do not have any leaks so I think its sorted.

Last edited by Graufuchs; 01-30-2024 at 08:39 AM.
Old 01-30-2024 | 11:24 AM
  #22  
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Originally Posted by E39Nutz
i replaced all 8 bleeder screws in my last brake bleed (about 2 years ago). They weeped (like yours) for about 2 weeks, then stopped. At first i wiped them clean and after a week i gave up. Another week went by, the wet area did not seem to expand, i cleaned them up and it had stopped. To date, the areas are still dry. I supposed the brake fluid dried up that helped seal the weeping. Regardless, i am happy that the brakes stopped crying.
I don't think brake fluid "dries up" - if it did, we'd all have major issues.
Old 01-30-2024 | 05:45 PM
  #23  
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DOT4 brake fluid wet boiling point is 155 degreeC, so the exposed brake fluid would vaporize when the brakes are hot enough. I should have called it vaporized rather than “dried up”. Regardless, the brake hydronic system is a closed system. If just the exposed fluid “dried up”, it does not create any issue unless the system continues to leak.



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