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2000 A6 4.2 Brake Caliper leaking after replacement

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Old 07-26-2014, 09:30 AM   #1
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Default 2000 A6 4.2 Brake Caliper leaking after replacement

Hi all, I recently replaced the rear brake rotors and also put in reconditioned brake calipers. The right wheel is fine but the left drivers side wheel started dripping brake fluid after I started to pump the brakes to get brake pressure back up.

I took off the brake line again and reconnected it a couple of times and tightened it as hard as I could without damaging the bolt and the caliper. That seemed to help but it still keeps dripping a bit.

Not sure what else to do. Is there any kind of sealer I can put around the edges of the nut? Thanks.
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Old 07-26-2014, 09:55 AM   #2
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Do you still have the old copper washers from the previous caliper? If you do, reuse those. If you don't then you'll need to throw out the washers that you have and get new ones and try again.

There are no sealers that can be used with the braking system. There's too much pressure and it would just get blown out. Not to mention it could potentially contaminate the system.
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Old 07-26-2014, 02:37 PM   #3
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New soft copper washers.
Not reused ones, and not hard copper.
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Old 07-26-2014, 03:18 PM   #4
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not hard copper.
Please use quote and reply so your posts thread correctly. Your comments seem random since they are all over the place.
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Old 07-26-2014, 03:32 PM   #5
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teflon tape on the threads?

remember it gets HOT.

Odd, i've never had an issue

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Old 07-26-2014, 03:54 PM   #6
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Originally Posted by N_Jay View Post
New soft copper washers.
Not reused ones, and not hard copper.
You can reuse the factory copper washers no problem. As a matter of fact, they work better than the new ones that come with replacement calipers.
The factory washers are thicker, they also have ridges cut into them so they seal better with less torque.

Note: they have to be the ones that came off of that particular vehicle, and reinstalled in the same orientation that they came off.

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teflon tape on the threads?

remember it gets HOT.

Odd, i've never had an issue

Grant
The leak is not on the threads most likely. I'm betting it's it's coming from the copper washer area by the bolt head. Note that these use banjo bolts that are basically hollow to allow fluid to pass through them.

No sealants, teflon tape, or any other chemical may be used in a braking system except for brake fluid itself. It is vitally important that the system seals itself mechanically. Not only does the system get extremely hot, it also is under a considerable amount of pressure (think 2000 psi in some cases).
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Old 07-26-2014, 05:25 PM   #7
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Is it actually leaking from the banjo bolt, or from somewhere else?
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Old 07-26-2014, 07:14 PM   #8
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Originally Posted by P-Zero View Post
Do you still have the old copper washers from the previous caliper? If you do, reuse those. If you don't then you'll need to throw out the washers that you have and get new ones and try again.

There are no sealers that can be used with the braking system. There's too much pressure and it would just get blown out. Not to mention it could potentially contaminate the system.
The only washers I see are the ones on the end of the brake line which has a metal connector that the bolt goes thru. It has a washer on either of the connector. They don't look like they're made of copper and they are the ones that were on the car when I got it. I will look for copper ones and try those. Thanks.
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Old 07-26-2014, 07:16 PM   #9
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Originally Posted by N_Jay View Post
New soft copper washers.
Not reused ones, and not hard copper.
Okay, will try those, thanks for the suggestion.
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Old 07-26-2014, 07:18 PM   #10
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Is it actually leaking from the banjo bolt, or from somewhere else?
Yes, it is leaking from the bolt. At first, I saw it leaking from the pin that is used to align the brake line to the caliper but after I tightened it real hard it seemed to stop and start dripping out from under the bolt head.
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Old 07-26-2014, 07:21 PM   #11
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Originally Posted by P-Zero View Post
You can reuse the factory copper washers no problem. As a matter of fact, they work better than the new ones that come with replacement calipers.
The factory washers are thicker, they also have ridges cut into them so they seal better with less torque.

Note: they have to be the ones that came off of that particular vehicle, and reinstalled in the same orientation that they came off.



The leak is not on the threads most likely. I'm betting it's it's coming from the copper washer area by the bolt head. Note that these use banjo bolts that are basically hollow to allow fluid to pass through them.

No sealants, teflon tape, or any other chemical may be used in a braking system except for brake fluid itself. It is vitally important that the system seals itself mechanically. Not only does the system get extremely hot, it also is under a considerable amount of pressure (think 2000 psi in some cases).
Yes, that's right, that is where its coming from. Will try the copper washers as suggested by the other kind posters.

Will stay away from Sealants then. Thank you.
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Old 07-27-2014, 01:43 PM   #12
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Quote:
Originally Posted by P-Zero View Post
You can reuse the factory copper washers no problem. As a matter of fact, they work better than the new ones that come with replacement calipers.
The factory washers are thicker, they also have ridges cut into them so they seal better with less torque.

Note: they have to be the ones that came off of that particular vehicle, and reinstalled in the same orientation that they came off.

. . . .
The sealing washers are Annealed Copper (Very soft) "Crush Washers".
They are designed to crush when tightened and act as a gasket.
The ridges you see are not put in the washers when they are made, but are the result of this crushing.
When the copper is crush it becomes "Work Hardened" and will no longer work to form a seal as well the second time.

Lots of facts (and non-facts) here. (Fairly easy to tell who knows what as you read.)

Last edited by N_Jay; 07-27-2014 at 01:47 PM.
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Old 07-27-2014, 06:51 PM   #13
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Quote:
Originally Posted by N_Jay View Post
The sealing washers are Annealed Copper (Very soft) "Crush Washers".
They are designed to crush when tightened and act as a gasket.
The ridges you see are not put in the washers when they are made, but are the result of this crushing.
When the copper is crush it becomes "Work Hardened" and will no longer work to form a seal as well the second time.

Lots of facts (and non-facts) here. (Fairly easy to tell who knows what as you read.)
Well, it's more obvious who's about theory and who's about actual work experience. I'm a certified mechanic, including brakes. I fix cars for a living. What is it that you do exactly?

I have reused factory washers countless times, and guess what? They seal EVERY time. Unlike the new washers that are nearly half as thick and, more often than not, don't seal, and require A LOT more torque to get them to seal. To the point where you're about to break things.
And I'm quite aware that they're a crush washer and I'm very well aware that the ridges that are cut into them are from assembly and not made that way. (The ridges are in the brake hose connector)
However, being that the factory washer is over twice as thick, and being that it is copper; a relatively soft metal, it can reseal a second time with no issues.
Yes, technically you're supposed to replace them, however, the new ones are really bad, worse than the used ones, unless you get factory washers.
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Old 07-27-2014, 07:29 PM   #14
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. . . . . Yes, technically you're supposed to replace them, however, the new ones are really bad, worse than the used ones, unless you get factory washers.
So when someone is having problems, whet do you recommend?

Maybe a few new, proper (not eBay special), washers?

If you use the old washer and it works, great.
But when it doesn't to keep trying is foolish.

Last edited by N_Jay; 07-27-2014 at 07:32 PM.
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Old 07-28-2014, 07:07 AM   #15
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So anneal the copper washer(s). Put them on an electric stove element (clean them first), heat them red hot, remove them from the stove and let them air cool.
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Old 07-28-2014, 07:13 AM   #16
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Originally Posted by ather View Post
Hi all, I recently replaced the rear brake rotors and also put in reconditioned brake calipers. The right wheel is fine but the left drivers side wheel started dripping brake fluid after I started to pump the brakes to get brake pressure back up.

I took off the brake line again and reconnected it a couple of times and tightened it as hard as I could without damaging the bolt and the caliper. That seemed to help but it still keeps dripping a bit.

Not sure what else to do. Is there any kind of sealer I can put around the edges of the nut? Thanks.
Try annealing the copper washers after cleaning them. Heat them red hot on an electric stove element or gas stove or propane torch. Air cool the washer and then use it.

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Old 07-28-2014, 07:18 AM   #17
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There are many metal washers/seals on the car, among them are the power steering connections at the power steering pump and essentially any banjo bolt-type fluid connections. I've worked on motorcycles and cars for over 50 years…annealing used copper washers is a common solution to reusing them. New ones are the best, but annealing works well.
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Old 07-28-2014, 07:26 AM   #18
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Quote:
Originally Posted by ather View Post
The only washers I see are the ones on the end of the brake line which has a metal connector that the bolt goes thru. It has a washer on either of the connector. They don't look like they're made of copper and they are the ones that were on the car when I got it. I will look for copper ones and try those. Thanks.
And PS…annealing aluminum is tricky….the annealing temp is only 700F…and aluminum melts at 660C 0r 1220F, real easy to melt the stuff on an electric stove. Classic way to anneal aluminum is to put a soot coating (from a candle) on the part and then heat the part with a torch until the soot burns off…at walah! 700F.
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Old 07-28-2014, 08:14 AM   #19
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You mean you don't just "flip them over, and tighten it up real good"? (Smirk)
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Old 07-28-2014, 11:34 AM   #20
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You mean you don't just "flip them over, and tighten it up real good"? (Smirk)
Only if she's willing.
That's what she said….
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Old 07-28-2014, 11:34 AM
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