Omega Owners Forum
Chat Area => General Car Chat => Topic started by: johnnydog on 16 January 2026, 22:38:25
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Wondered if any of you knowledgables have had any experiences of this issue...
I have a set of ceramic front brake calipers on an Audi (which I believe are made by Brembo). The inner bleed nipple on both calipers have seized primarily I presume as the bleed nipple is steel and the caliper body is alloy causing corrosion between the different metals
The brake system has been bled religiously every two years.
I have a chap who has had success of removing seized / snapped bleed nipples so I'm not overly concerned about getting out - but should I replace them with stainless steel or titanium alternatives?
I have researched this on t'interweb, and I'm leaning towards a high grade of stainless with maybe a smear of ceramic brake grease or red rubber grease on the thread, but there is some suggestion that titanium and alloy are possibly better suited to the different metals, although there will aways be some reaction over time.
I am a little miffed that dispite them being slackened to bleed every two years they have seized, but if I can reduce the likelihood of this problem in the future, which alternative metal bleed nipple would be best?
Thanks
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I'd tend towards stainless, because you've only got to look at titanium bolts and they snap.
You are fitting rubber caps to keep the nipples clear? Most of the seized ones I've seen have been where the sealing taper at the bottom was corroded
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Thanks Nick - they have always had the rubber caps on the nipples. Stainless was my thoughts too of the the two metals from what I've read. Checked the cost of them and they aren't too bad price wise either.
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After doing more digging, I think I will stick with original Brembo /Audi steel replacement bleed nipples.
Reasoning behind it - galvanic corrosion when two types of metals are in contact with each other (as we all know), and an electrolyte (humidity / rainwater/ sea or salt water etc). Alloy calipers are made from an aluminim alloy I understand, and this corrosion requires an anode and cathode to start the process, if the two metals are similar this process is reduced.
Unfortunately stainless steel and aluminium alloy are more prone to electron transfer, and titanium even more so; mild steel or zinc plated steel less so. In other words the more similar the metal are between anode and cathode, the less galvanic corrosion occurs.
You would have thought the engineers at Brembo would fit the most appropriate bleed nipples for the metal in their calipers, so with that in mind, I am going to stick with their standard bleed nipples. I'm not saying galvanic corrosion won't occur again, but with a barrier on the threads such as ceramic grease or red rubber grease (being unaffected by brake fluid) should help to reduce the effect.
Took some research but stainless in alloy, and titanium in alloy are not recommended at all unless sleeved with a more compatible metal.
Now have to get the snapped and seized bleed nipples out...... ::)
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I have had the same dilemma and come to the same conclusion. One nipple was really seized in and the torx bit I hammered in sheared off >:(.
I now have an induction heater (about £120 from Aliexpress) that I'll try next time it happens.
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I have had the same dilemma and come to the same conclusion. One nipple was really seized in and the torx bit I hammered in sheared off >:(.
I now have an induction heater (about £120 from Aliexpress) that I'll try next time it happens.
Interested to hear how you get on with the induction heater. Nearly bought one last summer, but they were around the £400 make. Didn't think to check the Ching Chong sellers....
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Interested to hear how you get on with the induction heater. Nearly bought one last summer, but they were around the £400 make. Didn't think to check the Ching Chong sellers....
Well if you hold a bolt in a pair of pliers the coil will get it cherry red. That's as far as I have gone so far. They are quite fragile - you can break them if you use it with no coil, nothing in then centre of the coil or use it for too long in one go. However for me it's to release those corroded nuts and bolts that might otherwise shear so it'll get occasional strategic use. The big one I have in mind for it is to free the track rod adjuster on one of my cars, in that case I need to unwind and rewind the coil around the track rod. I'm not sure it'll have the welly to do it but I'll have a go, I know I couldn't free it with anything else. Mine is supposedly 1300W.
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I'm thinking on same lines JasonH - limited use for those bolts that need heat to remove, but not able to get heat in either due to space or nearby components.
I know I probably have a seized bolt on her car, but not even one of those will likely free that up, so know it's not a miracle cure.
For a little over £100, it might be worth a punt - do you have the item number (or link to) yours?
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This is the one I bought, it's gone up little now:
https://www.aliexpress.com/item/1005009611476462.html (https://www.aliexpress.com/item/1005009611476462.html)
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Make sure you click the UK plug option....
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This is the one I bought, it's gone up little now:
https://www.aliexpress.com/item/1005009611476462.html (https://www.aliexpress.com/item/1005009611476462.html)
Thanks :y
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After doing more digging, I think I will stick with original Brembo /Audi steel replacement bleed nipples.
Put a tiny smear of hylomar blue on the threads, although now commonly used as a sealant, Rolls Royce originally invented it to prevent galvanic corrosion on aerospace components. Its specc'd to around 250c if memory serves, which if you've got that temperature in the top of the calipers, probably means you're boiling your brake fluid :D
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Cheers Jim. That seems like a good alternative.
As the bleed nipples should be slackened every two years for bleeding, would that not destroy the seal between the threads and the alloy caliper body possibly resulting in future galvanic corrosion? If they were being removed the threads could he cleaned and more Hylomar applied, but how do you thik would the sealant stand up to just being slackened to bleed?
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The hylomar isn't there for its sealing properties per se, its to form a thin layer between the metals.
Hylomar blue doesn't set so shouldn't be affected by winding in and out. I'd be tempted to just add a little smear to the exposed threads as you slacken them off for bleeding. :y
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The tip of the bleed nipple seats against a concave machined surface inside the caliper body.
Over tightening can make them.leak just as much as not tightening them.
If you need to add sealant you're doing it wrong. A wipe of oil on the threads would work just as well although the stuff Jim suggests will certainly be effective. And as suggested, the word 'sealant' in this case means sealing the surfaces from each other, not to keep the brake fluid in.
An alternative option would be to treat the nipples as a service item and replace them with the fluid. You may find that Brembo actually recommended this.