View Full Version : weeping nipples :-0
my nipples are weeping, what can I do ? :rolleyes:
I have a brake bleed nipple that appears perfectly sound and clean but it seems to weep fluid up the threads. Anybody know any tricks to sort this?
I've seen a paste similar to thread lock before now thats intended for bleed nipple threads. Any idea what it is and where I might get some?
The bleed nipple should have a seal in the caliper that it goes into, is that in good nick?
Alpinestarhero
29-02-08, 02:00 PM
tried using a bit of PTFE (teflon) tape round the thread, when you put the bolt on?
Matt
jumjum_0214
29-02-08, 02:05 PM
I had this problem so i just nipped up the nipple :D Its ok now :cool:
Yeah the seals 'appeared' to be fine but I may need to remove and check again. I have some replacement hoses coming that I need to fit anyway so thats no problem.
I like the PTFE idea, especially for the brake bleeding phase to save fluid leaking everywhere.
I've had new nipples supplied before that came with a type of threadlock compount, wondered if anybody had seen/used this before.
Blue_SV650S
29-02-08, 02:34 PM
The nipple seals via the conical end, make sure the end and its recess is clean. Putting PTFE (or whatever) round the threads is like sticking a bung in the end of an overflow pipe as something is overflowing … it might stop it coming out for a bit, but its not solving the problem ;)
I like the PTFE idea, especially for the brake bleeding phase to save fluid leaking everywhere.
Everytime I touch my nipples (oo-eer) I take the PTFE off & put new stuff on there. Habit I suppose.
The nipple seals via the conical end, make sure the end and its recess is clean. Putting PTFE (or whatever) round the threads is like sticking a bung in the end of an overflow pipe as something is overflowing … it might stop it coming out for a bit, but its not solving the problem ;)
Yeah I understand that, I think where the ptfe might be useful is during brake bleeding itself. As soon as you undo the nipple each time you usually get fluid escaping up via the thread, PTFE might well stop this. But once bled yeah the pressure should be totally contained by the nipple seal itself.
Blue_SV650S
29-02-08, 03:02 PM
Yeah I understand that, I think where the ptfe might be useful is during brake bleeding itself. As soon as you undo the nipple each time you usually get fluid escaping up via the thread, PTFE might well stop this. But once bled yeah the pressure should be totally contained by the nipple seal itself.
So it seals ok, just weeps when you bleed right? :confused:
If so - what are you worried about?!!? :confused:
So it seals ok, just weeps when you bleed right? :confused:
If so - what are you worried about?!!? :confused:
No I think we are talking about two different things in the thread. My actual problem is that the system is weeping through one front nipple and the rear does the same when everything is supposed to be sealed shut and the nipples are tightly seated. For that part then there must be something wrong with the seal itself which I'll have to check out.
The other side of this is that I think PTFE tape (or this mystery compound that I cant identify) can be useful to prevent fluid ****ing all over the place when bleeding the calipers.
The other side of this is that I think PTFE tape (or this mystery compound that I cant identify) can be useful to prevent fluid ****ing all over the place when bleeding the calipers.
"Bung in the overflow" is exactly right. When bleeding, as you know, fluid comes out the hole in the centre of the nipple. But to do this, the nipple has to be loosened, and the PTFE stops the creep (or gush, as it may be) up the threads (as mentioned).
If you're leaking when the nipples are tight, I'd agree culprit is the seals, or new nipples themselves (if they've been mistreated for example).
Blue_SV650S
29-02-08, 03:38 PM
How far are you undoing the nipples when you bleed them?? You only need ~1/4 -1/2 turn and it really is a very small weep nothing to worry about …
You say ‘seals’ .. it sound like it is something you can replace, like a rubber seal. But a nipple is solid metal, as is the calliper side, it is the shape of the end of the nipple and the recess that makes the seal (and the seat deforming very slightly). If the calliper nipple seat is damaged, then it is new calliper time … I’d investigate this sooner rather than later ;)
Its probably just a bit of **** on the conical bit that can simply be washed free 8)
Its probably just a bit of **** on the conical bit that can simply be washed free 8)
Thats exactly what I'm thinking. The calipers have been fully stripped and cleaned and there was no obvious damage to either the caliper or the nipple side of the 'seal' ....yes I was referring to the conical surface.
strange though as I did give 'em a good blast of compressed air during cleaning. I small peice of crap could always have got in there though.
No worries, I've got to strip 'em again anyway so I'll take a closer look at the surfaces.
Alpinestarhero
29-02-08, 04:03 PM
I like the PTFE idea
thangyow :takeabow:
Matt
People keep saying 'Nipples'...
... tee hee hee. ;)
mmmstrongbow
29-02-08, 04:31 PM
liquid ptfe is called swak its made by swagelok, i dont know if its what your looking for but it sounds like it is. not very easy to get hold of unless your in industry
Robw#70
29-02-08, 08:45 PM
This is all far too complicated!!!
When you bleed the brakes fluid comes through the centre of the bleed nipple, the bottom of the bleed nipple has a taper which seals in a seat when tightened, when you loosen the bleed nipple fluid also weeps up the threads, because the taper is at the bottom, when its tight its sealed...
There will still be a residue of fluid in the nipple and in the threads, you can soak some of the fluid from the centre with a tissue, but there will still be fluid in the threads.
When you put the dust cap on the nipple it will pressurise the remaining fluid in the nipple which in turn forces it out of the threads, no leak just excess fluid.
Leave the dust covers off, wash the calipers with water (still attached to bike dont go mad just rinse) use the bike to get calipers hot, then replace dust covers.
bad-sv650
29-02-08, 10:49 PM
People keep saying 'Nipples'...
... tee hee hee. ;)
I perfer to play with my misses nipples :offtopic: :-#
jumjum_0214
10-03-08, 04:29 PM
Did you ever fix your nips mate?? Mine are weeping :-(
Did you ever fix your nips mate?? Mine are weeping :-(
Yes I did. There are two seperate conditions though;
The nipples were weeping during bleeding due to the fluid seeping up the thread each time the nipple was loosened off. This is generally normal but just a little messy. The solution to this that I found works really well was to put a couple of turns of PTFE tape around the nipple thread (same stuff as used in water plumbing).
The other problem on one of the nipples was very slight weeping when the nipple was tightened. This should not happen and the PTFE should not be used to 'solve' this. In my case it was simply down to a build up of material on the coned sealing section of the nipple itself. This cone must be clean and a good seal against the bottom of the nipple hole in the caliper. I gently polished the coned section with a brass wire brush tool on my dremel and refitted. Sorted it out perfectly.
If the coned section of the nipple or the hole it goes into is badly damaged then either the caliper or the nipple must be replaced.
What ever you do dont overtighten the nipples to compensate as you'll strip the threads in the caliper.
Also, I found that ProBolt sell replacement brake nipples in stainless steel. Worth it for a few quid. Nice and shiny too! :)
jumjum_0214
10-03-08, 05:50 PM
"What ever you do dont overtighten the nipples to compensate as you'll strip the threads in the caliper".
Oh dear :smt022
"What ever you do dont overtighten the nipples to compensate as you'll strip the threads in the caliper".
Oh dear :smt022
uh oh, is that what happened?
Only two choices then are to re-drill and use a thread repair kit. This must be done very accurately though as the cone must seal properly. I've done it before successfully but if you arent up to the job I wouldnt attempt it yourself.
Secondly, replace the calipers.
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